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Clinical recommendations for cardiopulmonary exercise testing data assessment in specific patient populations

, , Marco Guazzi , Volker Adams , Viviane Conraads , Martin Halle , Alessandro Mezzani , Luc Vanhees , , Ross Arena , Gerald F. Fletcher , Daniel E. Forman , Dalane W. Kitzman , Carl J. Lavie , Jonathan Myers
DOI: http://dx.doi.org/10.1093/eurheartj/ehs221 2917-2927 First published online: 5 September 2012

Table of Contents

  • Abbreviation list 2918

  • Introduction 2918

  • What is CPX 2918

  • Defining key CPX variables 2919

  • Universal CPX reporting form 2923

  • Unique Condition-related CPX variables according to test indication

  • Systolic heart failure 2923

  • Heart failure with preserved ejection fraction and congenital heart disease 2923

  • Hypertrophic cardiomyopathy 2924

  • Unexplained exertional dyspnoea 2924

  • Suspected or confirmed pulmonary arterial hypertension or secondary pulmonary Hypertension 2925

  • Confirmed chronic obstructive pulmonary disease or interstitial lung disease 2925

  • Suspected myocardial ischaemia 2926

  • Suspected mitochondrial myopathy 2926

  • Directions for future research 2927

  • Conclusions 2927

  • References 2927

Appendices

  1. Universal CPX reporting form

  2. Prognostic and diagnostic stratification for patients with heart failure

  3. Prognostic and diagnostic stratification for patients with confirmed or suspected hypertrophic cardiomyopathy

  4. Diagnostic stratification for patients with unexplained dyspnoea

  5. Prognostic and diagnostic stratification for patients with suspected or confirmed pulmonary arterial hypertension/secondary pulmonary hypertension

  6. Prognostic and diagnostic stratification for patients with chronic obstructive pulmonary disease or interstitial lung disease

  7. Diagnostic stratification for patients with suspected myocardial ischaemia

  8. Diagnostic stratification for patients with suspected mitochondrial myopathy

Abbreviations

BP
blood pressure
CHD
coronary heart disease
CO2
carbon dioxide
COPD
chronic obstructive pulmonary disease
CPX
cardiopulmonary exercise testing
CRF
cardiorespiratory fitness
CV
cardiovascular
ECG
electrocardiogram
EIB
exercise-induced bronchospasm
EOV
exercise oscillatory ventilation
ET
exercise testing
FEV1
forced expiratory volume in 1 s
HCM
hypertrophic cardiomyopathy
HF
heart failure
HF-PEF
heart failure-preserved ejection fraction
HR
heart rate
HRR
heart rate recovery
ILD
interstitial lung disease
LVH
left ventricular hypertrophy
MVV
maximal voluntary ventilation
O2
oxygen
PAH
pulmonary arterial hypertension
PEF
peak expiratory flow
PETCO2
partial pressure of end-tidal carbon dioxide
PH
pulmonary hypertension
Q
cardiac output
RER
respiratory exchange ratio
SpO2
pulse oximetry
US
United States
VE
minute ventilation
Embedded Image
carbon dioxide production
Embedded Image
oxygen consumption
VT
ventilatory threshold

Introduction

From an evidence-based perspective, cardiopulmonary exercise testing (CPX) is a well-supported assessment technique in both the United States (US) and Europe. The combination of standard exercise testing (ET) [i.e. progressive exercise provocation in association with serial electrocardiograms (ECGs), haemodynamics, oxygen saturation, and subjective symptoms] and measurement of ventilatory gas exchange amounts to a superior method to: (i) accurately quantify cardiorespiratory fitness (CRF), (ii) delineate the physiologic system(s) underlying exercise responses, which can be applied as a means to identify the exercise-limiting pathophysiological mechanism(s) and/or performance differences, and (iii) formulate function-based prognostic stratification. Cardiopulmonary ET certainly carries an additional cost as well as competency requirements and is not an essential component of evaluation in all patient populations. However, there are several conditions of confirmed, suspected, or unknown aetiology where the data gained from this form of ET is highly valuable in terms of clinical decision making.1

Several CPX statements have been published by well-respected organizations in both the US and Europe.15 Despite these prominent reports and the plethora of pertinent medical literature which they feature, underutilization of CPX persists. This discrepancy is at least partly attributable to the fact that the currently available CPX consensus statements are inherently complex and fail to convey succinct, clinically centred strategies to utilize CPX indices effectively. Likewise, current CPX software packages generate an overwhelming abundance of data, which to most clinicians are incomprehensible and abstract.

Ironically, in contrast to the protracted scientific statements and dense CPX data outputs, the list of CPX variables that have proven clinical application is concise and uncomplicated. Therefore, the goal of this writing group is to present an approach of CPX in a way that assists in making meaningful decisions regarding a patient's care. Experts from the European Association of Cardiovascular Prevention and Rehabilitation and American Heart Association have joined in this effort to distil easy-to-follow guidance on CPX interpretation based on current scientific evidence. This document also provides a series of forms that are designed to highlight the utility of CPX in clinical decision-making. Not only will this improve patient management, it will also catalyze uniform and unambiguous data interpretation across laboratories on an international level.

The primary target audience of this position paper is clinicians who have limited orientation with CPX but whose caregiving would be enhanced by familiarity and application of this assessment. The ultimate goal is to increase awareness of the value of CPX and to increase the number of healthcare professionals who are able to perform clinically meaningful CPX interpretation. Moreover, this document will hopefully lead to an increase in appropriate patient referrals to CPX with enhanced efficiencies in patient management. For more detailed information on CPX, including procedures for patient preparation, equipment calibration, and conducting the test, readers are encouraged to review other publications that address these and other topics in great detail.15

What is cardiopulmonary exercise testing?

Despite advances in technologies related to diagnostic testing and the popularity of imaging techniques, the assessment of exercise responses provides critical enhancement of the evaluation of patients with or suspected of having cardiovascular (CV) or pulmonary disease.6 The measurement of CRF from ET has many clinical applications, including diagnosis, evaluation of therapy, risk stratification, and to guide physical activity. While exercise tolerance is commonly estimated from treadmill or bicycle cycle ergometer work rate, CPX is a specialized subtype of ET that provides a more accurate and objective measure of CRF. CPX relies on the measurement of ventilatory gases during exercise, i.e. a non-invasive procedure that involves the acquisition of expired ventilation and concentrations of oxygen (O2) and carbon dioxide (CO2) during progressive exercise. Admittedly, there are potential ‘patient difficulties’ associated with CPX (trepidation with the testing itself, mouthpiece/nose clip/mask difficulties, perception of limits in ‘air’ availability, etc.). However, when added to standard ET, the direct non-invasive measurement of ventilation and expired gases permits the most accurate and reproducible quantification of CRF, a grading of the aetiology and severity of impairment, and an objective assessment of the response to an intervention.7,8 Moreover, over the last two decades, a particularly large volume of research has been directed toward the utility of CPX as a prognostic tool; these studies have established CPX as a scientifically sound and therefore clinically valuable method for accurately estimating prognosis in various disease states.1,9,10 As will be described in this document, studies performed on the clinical applications of CPX have had an important influence on the functional assessment of patients with confirmed/suspected CV and pulmonary disease as well as those with certain confirmed/suspected musculoskeletal disorders.

Although still underutilized, CPX has gained popularity not only due to the recognition of its clear value in the functional assessment of patients with CV, pulmonary, and musculoskeletal disease/disorders, but also because of technological advances (e.g. rapid response analysers and computer-assisted data processing) which have made this modality easier to use. Once largely under the domain of the physiologist or specialized centre, CPX currently has the potential to be used for a wide spectrum of clinical applications. The basic CPX responses, O2 consumption Embedded Image, minute ventilation (VE), and CO2 production Embedded Image are now easily obtainable in the time-down spreadsheet format from most systems, providing a platform for straightforward data processing and interpretation. While standard ET has long been considered the gatekeeper to more expensive and invasive procedures (e.g. angiography, bypass surgery, transplantation, other medical management decisions), gas exchange measurements during exercise have been demonstrated to enhance the decision-making process. CPX responses have been demonstrated to be valuable in supplementing other clinical information to optimize risk stratification for cardiac transplantation listing, medical device therapy (e.g. implantable cardioverter-defibrillator and cardiac resynchronization therapy), consideration for lung resection or lung transplantation, and for a variety of pre-surgical evaluations.1,7,913 Because markers of ventilatory efficiency have emerged as particularly powerful prognostic markers, risk stratification paradigms that include these indices have also been proposed in recent years.1,13

Defining key cardiopulmonary exercise testing variables1423

The volume of data automatically generated by the software packages of CPX systems can be somewhat daunting to clinicians who do not have extensive experience with this form of ET. Moreover, the clinical significance of many of these variables, numerically and/or graphically depicted, has not been thoroughly vetted through original research. In contrast, the list of variables most pertinent in current clinical practice, and which are well substantiated by original research, is relatively concise. Key CPX variables, derived from both ventilatory expired gas analysis data and standard ET monitoring, are listed in Table 1. The intent of this table is to identify the key CPX variables and to provide only succinct descriptions or their significance and normal values/responses; more detailed accounts are provided elsewhere and the reader is encouraged to review these documents for additional details.14,24 Of particular note, aerobic capacity is defined as peak Embedded Image as opposed to maximal Embedded Image in this document as the former designation is most often used in patient populations with suspected/confirmed pathophysiological processes. All of the variables listed in Table 1 are included in the one-page, universal CPX reporting form (see Appendix 1). While some of these variables warrant assessment in all patients undergoing CPX, such as peak Embedded Image and the peak respiratory exchange ratio (RER), others, such as the Embedded Image slope and exercise oscillatory ventilation (EOV), are condition specific. A more refined identification of condition-specific CPX variables is described in subsequent sections and their respective appendices. The writing group hopes that this approach improves the ease by which the most pertinent data are identified and utilized by clinicians performing and interpreting CPX. Moreover, the majority of these variables are automatically included in reporting forms generated by current CPX system software packages.

View this table:
Table 1

Identification and defining normal responses for key cardiopulmonary exercise testing variables

CPX variableDescription/significanceNormal value/response
Peak Graphic (mL O2 • kg−1 • min−1)
  • Highest O2 uptake obtained during exercise

  • Commonly designated as ‘peak’ value in patient populations described in this document

  • Expressed as a 10–60 s averaged value depending on the ET protocol (i.e. shorter averaging interval for protocols with shorter stages and longer averaging interval for protocols with longer stages)1

  • Response influenced by central (CV and/or pulmonary) and peripheral (skeletal muscle) function

  • Broadly reflects disease severity in a number of patient populations including HF, HCM, PAH secondary PH, COPD, ILD

  • Universal prognostic marker

  • Wide range influenced by age and sex: ∼80–15 mL O2 • kg−1 • min−1 in young elite athlete and apparently healthy 80-year-old female, respectively;11 normal age-related decline related to decrease in central and peripheral performance across the lifespan; normal sex-related differences largely influenced by difference in maximal cardiac output

  • Reporting peak Graphic as a per cent-predicted value using equations provided in Table 2 recommended to account for age and sex differences.

  • Per cent-predicted values should be ≥100%

Graphic at VT (mL O2 • kg−1 • min−1)
  • Submaximal Graphic where there is a dislinear rise in VE and Graphic

  • Generally associated with anaerobic threshold

  • Represents upper limit of ET workloads that can be sustained for a prolonged period

  • Valuable in setting intensity for exercise prescription in a highly individualized manner

  • ≈ 50–65% of peak Graphic21

  • Influenced by genetic predisposition and chronic aerobic training

Peak RER
  • Defined as the Graphic ratio

  • Expressed as a 10–60 s averaged value depending on exercise protocol (i.e. shorter averaging interval for protocols with shorter stages and longer averaging interval for protocols with longer stages)

  • As exercise progresses to higher intensities, Graphic outpaces Graphic, increasing the ratio

  • Currently is the best non-invasive indicator of exercise effort

  • Peak value ≥1.10 widely accepted as excellent exercise effort1

Graphic slope
  • Relationship between VE, plotted on the y-axis, and Graphic plotted on the x-axis; both variables in L min−1

  • Most commonly calculated using all ET data7

  • Represents matching of ventilation and perfusion within the pulmonary system

  • Broadly reflects disease severity as well as prognosis in a number of patient populations including HF, HCM, PAH/secondary PH, COPD, ILD

<30 considered normal with slight increase with advanced age possible
EOV
  • No universal definition currently available

  • Most commonly defined as an oscillatory pattern at rest that persists for ≥60% of the exercise test at an amplitude of ≥15% of the average resting value1,16

  • Recommend using 10 s averaged VE data for plotting

  • Reflects advanced disease severity and poor prognosis in patients with HF

This is not a normal ventilatory response to exercise under any circumstances (see Figure 2)
PETCO2 (mmHg) at rest and during exercise
  • Also represents matching of ventilation and perfusion within the pulmonary system and cardiac function

  • Broadly reflects disease severity in a number of patient populations including HF, HCM, PAH/secondary PH, COPD, ILD

  • Rest: 36–42 mmHg

  • Increases between 3 and 8 mmHg by VT

  • Decrease following VT secondary to increased ventilation response

Graphic at peak exercise
  • Expressed as a 10–60 s averaged value depending on the exercise protocol (i.e. shorter averaging interval for protocols with shorter stages and longer averaging interval for protocols with longer stages)

  • Reflects ventilatory cost of O2 uptake at peak ET

  • Has diagnostic utility in patients with suspected mitochondrial myopathy

  • ≤ 40

  • 50 = upper limit of normal response22

Graphic slope
  • Relationship between Q, plotted on the y-axis, and Graphic plotted on the x-axis; both variables in L min−1

  • Additional equipment needed to measure Q; through foreign gas rebreathing technique1

  • Reflects the relationship between O2 delivery and utilization in exercising skeletal muscle

  • Has diagnostic utility in patients with suspected mitochondrial myopathy if anaemia is ruled out

≈5
VE/MVV
  • Ratio between VE at maximal exercise and MVV obtained at rest; both variables in L min−1

  • Although prediction equations are available (FEV1 × 4023), MVV should be directly measured

  • Has diagnostic utility in determining if unexplained exertional dyspnoea is related to a pulmonary mechanism

≤0.80
FEV1 (L • min−1) and PEF (L • min−1)
  • Components of pulmonary function testing battery

  • Predicted values automatically generated by CPX unit software packages; influenced by age, sex and body habitus

  • Has diagnostic utility in determining if unexplained exertional dyspnoea is related to a pulmonary mechanism, particularly exercise-induced bronchospasm

  • When relevant, should be assessed prior to and following CPX for comparative purposes

<15% reduction from pre to post CPX for both variables
O2 pulse trajectory (mL O2 • beat−1)
  • O2 pulse defined as the ratio between Graphic (mL O2 • min−1) and HR (b.p.m.)

  • Non-invasively reflects stroke volume response to exercise

  • Has diagnostic utility in patients with suspected myocardial ischemia (i.e. exercise-induced left ventricular dysfunction)

Continual linear rise throughout exercise with possible plateau approaching maximal exertion (see Figure 1)
Graphic trajectory (mL • min−1 • W−1)
  • Plot of the relationship between Graphic (y-axis in mL min−1) and workload (x-axis in W)

  • Lower extremity ergometer should be used as exercise mode when assessed

  • Has diagnostic utility in patients with suspected myocardial ischaemia (i.e. exercise-induced left ventricular dysfunction)

  • Continual linear rise throughout ET (see Figure 1)

  • Average slope, calculated with all exercise data, is 10 mL • min−1 • W−1

Exercise HR (b.p.m.)
  • In patients not prescribed a beta-blocking agent; provides insight into chronotropic competence and cardiac response to exercise

  • Peak HR should not be used as the primary gauge of subject effort given its wide variability19,20

  • Increase ∼10 beats per 3.5 mL O2 • kg−1 • min−1 increase in Graphic, achieve at least 85% of age-predicted maximal HR with good effort

HRR at 1 min (beats)
  • Difference between maximal exercise HR and HR 1 min into recovery

  • Provides insight into speed of parasympathetic reactivation

>12 beats
Exercise BP (mmHg)Provides insight into CV response to exercise and left ventricular afterload
  • SBP increase ∼10 mmHg per 3.5 mL O2 • kg−1 • min−1 increase in Graphic

  • Upper range of normal maximal SBP is ∼210 mmHg for males and ∼190 mmHg for females

  • DBP remains the same or slightly decreases

SpO2 (%)
  • Non-invasive estimate of arterial haemoglobin saturation

  • Has diagnostic utility in determining if unexplained exertional dyspnoea is related to a pulmonary mechanism

  • Desaturation common in patients with COPD, ILD, PAH/secondary PH as disease severity advances

  • ≥ 95% at rest and throughout exercise

  • Should not decrease >5% (absolute value)

ECG
  • Insight into stability of cardiac rhythm

  • Identifies baseline abnormalities and exercise-induced ischaemia

  • Minimal waveform changes

  • No significant deviation from normal sinus rhythm

Subjective symptoms
  • Used to determine subjects perception of symptoms limiting exercise

  • Rating of perceived exertion (i.e. Borg scale)15 as well as dyspnoea and angina (using symptom specific scales)17 should be quantified using separate scales with unique verbal anchors

  • Unusual dyspnoea as primary reason for test termination (i.e. 4/4: severely difficult, patient cannot continue)17 shown to indicate increased adverse event risk in patients assessed for myocardial ischemia14 and HF18

  • Limiting factor muscular fatigue with no significant dyspnoea or angina

  • CPX, cardiopulmonary exercise testing; Graphic, oxygen consumption; ET, exercise testing; VT, ventilatory threshold; VE, minute ventilation; Graphic, carbon dioxide production; RER, respiratory exchange ratio; EOV, exercise oscillatory ventilation; PETCO2, partial pressure of end-tidal carbon dioxide; HF, heart failure; HCM, hypertrophic cardiomyopathy; PAH, pulmonary arterial hypertension; PH, pulmonary hypertension; COPD, chronic obstructive pulmonary disease; ILD, interstitial lung disease; Q, cardiac output; MVV; maximal voluntary ventilation; PEF, peak expiratory flow; FEV1, forced expiratory volume in 1 s; O2, oxygen; W, watt; HR, heart rate; HRR, heart rate recovery; BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure; SpO2, saturation of peripheral oxygen; ECG, electrocardiogram.

Depending on system configuration, standard ET measures, such as haemodynamics and heart rate (HR), will either be reported alongside ventilatory expired gas analysis data or reported separately. In either situation, the majority of essential data is readily obtained. O2 pulse and (change in Embedded Image Embedded Image plots are often generated by customary CPX software systems. If this is not the case, the plots can be easily generated using the exercise data reported in time-down spreadsheet format. Examples of normal and abnormal O2 pulse and Embedded Image plots are illustrated in Figure 1.

Figure 1

Normal (dashed line) and abnormal (solid line) example of oxygen pulse and ΔVO2W plots. VO2, oxygen consumption; W, watts; O2, oxygen.

While VE data are graphically depicted, determination of EOV must be performed manually at this time. Given the importance of determining EOV in heart failure (HF), the writing group anticipates that the presence or absence of this abnormality, according to universally adopted criteria, will be automatically quantified by future CPX system software packages. The most frequently used criteria currently to define EOV are listed in Table 1.16 There is initial evidence to indicate that this set of EOV criteria provides more robust prognostic insight compared with other methods.25 For present clinical applications, the writing group recommends rest and exercise VE data be graphically depicted using 10-s averaged samples. This averaging interval allows for the removal of breath-by-breath signal noise while preventing excessive data smoothing and loss of the physiological phenomena that is brought about by averaging over longer intervals (i.e. data used for graphic illustration listed as ≥30 s averaging). A normal ventilatory pattern is contrasted to EOV in Figure 2.

Figure 2

Examples of normal ventilatory pattern (A) and exercise oscillatory ventilation pattern (B). VE, minute ventilation.

Lastly, when the additional assessment of non-invasive cardiac output (Q) is performed (e.g. CPX for suspected mitochondrial myopathy), the Embedded Image slope can be easily determined from the ET data in time-down spreadsheet format.

Universal cardiopulmonary exercise testing reporting form

The ability to collect all relevant CPX data in a concise and organized manner is essential for meaningful data interpretation and clinical utilization. The universal CPX reporting form included as Appendix 1 provides clinicians with the ability to collect relevant ET data that may subsequently be used for interpretation according to a patient's specific condition/test indication. It should be noted that some of the variables in the CPX reporting form will be collected irrespective of the reason for ET. This includes peak Embedded Image, per cent-predicted peak Embedded Image, Embedded Image at ventilatory threshold (VT), peak RER, HR, blood pressure (BP), ECG, and subjective symptom data. To calculate per cent-predicted peak Embedded Image, the writing group proposes using the equations put forth by Wasserman and Hansen,26,27 which are listed in Table 2. These equations account for several influencing factors including body habitus, mode of exercise, and sex. The aforementioned variables are relevant to all patients undergoing CPX because of their ability to universally reflect prognosis, maximal and submaximal functional capacity, exercise effort, and exertional physiology.28,29 The collection of other CPX variables included in the universal CPX reporting form are dictated by test indication and described in subsequent sections and appendices.

View this table:
Table 2

Predicted peak oxygen consumption equations

Wasserman/Hansen equationsaSedentary male

Step 1: Calculate

Cycle factor = 50.72 – 0.372(age)

Predicted weight = 0.79 (height) – 60.7

Step 2: Classify weight

Measured weight= predicted weight

Step 3: Select equation

Measured weight < Predicted weight

Peak Graphic (mL • min−1) = [(Predicted weight + Actual weight)/2] × cycle factor

Measured weight = Predicted weight

Peak Graphic (mL • min−1) = Measured weight × cycle factor

Measured weight > Predicted weight

Peak Graphic (mL • min−1) = (Predicted weight × cycle factor) + 6 × (Measured weight – predicted weight)

Step 4: Mode of exercise consideration

If treadmill used for test

Multiply predicted Graphic from step 3 × 1.11
Sedentary Female

Step 1: Calculate

Cycle factor = 22.78 – 0.17 (age)

Predicted weight = 0.65 (height) – 42.8

Step 2: Classify weight

Measured weight = predicted weight

Step 3: Select equation

Measured weight < Predicted weight

Peak Graphic (mL • min−1) = [(Predicted weight + Actual weight +86)/2] × cycle factor

Measured weight = Predicted weight

Peak Graphic (mL • min−1) = (Measured weight + 43) × cycle factor

Measured weight > Predicted weight

Peak Graphic (mL • min−1) = (Predicted weight + 43) × cycle factor + 6 × (Measured weight – predicted weight)

Step 4: Mode of exercise consideration

If treadmill used for test

Multiply predicted Graphic from step 3 × 1.11
  • Graphic, oxygen consumption.

  • aHeight in cm and weight in kg.

Unique condition-related cardiopulmonary exercise testing variables according to test indication

There are several suspected/confirmed conditions where performance of a CPX would provide clinically valuable information on diagnosis, prognosis, and/or therapeutic efficacy. However, the volume of scientific evidence supporting the value of CPX is heterogeneous across the conditions identified in subsequent sections. While the clinical use of CPX is firmly established in patients with systolic HF and unexplained exertional dyspnoea, additional research, to varying degrees, is needed to further bolster support for CPX in the other patient populations identified in this document. This is not to suggest that a clinical justification for CPX cannot be made for each of the conditions listed below. Moreover, the unique condition-related CPX variables proposed for analysis are based on a sound physiological rationale, expert consensus, and current scientific evidence. The writing group feels that, based on expert opinion and currently available evidence, CPX provides valuable clinical information in all of the conditions listed in subsequent sections. Each of the following sections is accompanied by a condition-specific evaluation chart (see Appendices 2–8). These charts include key CPX variables for each test indication in a colour-coded format. Responses in the green zone indicate a normal response for a given variable, while responses in the yellow and red zones indicate progressively greater abnormalities. An interpretation, based on CPX performance for key variables, is included at the end of each chart. The intent of these condition-specific charts is to greatly simplify CPX data interpretation, thereby improving clinical utility.

Systolic heart failure

The majority of research assessing the clinical application of CPX has been performed within the systolic HF population. Beginning in the 1980s with the landmark work by Weber et al.,30 followed in 1991 with the classic investigation by Mancini et al.,31 a wealth of literature has been put forth that convincingly demonstrates the ability of key CPX variables to predict adverse events and gauge disease severity.1,7,32,33 Peak Embedded Image and the Embedded Image slope are currently the most studied CPX variables in patients with systolic HF and both demonstrate strong, independent prognostic value. While there is evidence to indicate the Embedded Image slope is a stronger univariate predictive marker compared with peak Embedded Image, there is substantial evidence to indicate that a multivariate approach improves prognostic accuracy.7 Under current medical management strategies, a Embedded Image slope ≥45 and a peak Embedded Image <10.0 mL O2 • kg−1 • min−1 are indicative of a particularly poor prognosis over the 4-year period following CPX.34 Other CPX variables have emerged in recent years that appear to further refine prognostic resolution. Specifically, EOV and the partial pressure of end-tidal CO2 (PETCO2) during rest and exercise have both demonstrated strong prognostic value in patients with systolic HF.16,3537 Given these variables are readily available, their inclusion for prognostic assessment purposes is recommended. Lastly, there is some evidence to indicate the assessment of per cent-predicted peak Embedded Image may provide prognostic information,3840 although it is not clear if such information supersedes/compliments the prognostic strength of measured peak Embedded Image. Current evidence indicates that a per cent-predicted peak Embedded Image value falling below 50% indicates a poor prognosis in patients with HF.38 Research assessing the clinical value of per cent-predicted peak Embedded Image assessment in patients with HF should continue. However, given the disparity in the volume of supporting evidence for the prognostic value of measured peak Embedded Image vs. per cent-predicted peak Embedded Image, we currently recommend the actual peak Embedded Image value being considered in this patient population to gauge disease severity and prognosis. The prognostic and diagnostic stratification chart for patients with systolic HF is provided in Appendix 2. The peak Embedded Image, the Embedded Image slope, presence/absence of EOV, and rest/exercise PETCO2 should all be assessed. As values for these variables progress to the red zone, disease severity worsens and the likelihood of major adverse events (i.e. death, HF decompensation to the refractory stage) becomes increasingly likely. The risk for softer endpoints, such as hospitalization due to HF, is also likely to increase as variables progress to the red zone. With respect to transplant candidacy, the peak Embedded Image and Embedded Image slope values in the red zone should be considered primary criteria for eligibility. Numerous investigations have demonstrated the aforementioned CPX variables respond favourably to pharmacological (i.e. sildenafil, angiotensin receptor blockade, angiotensin-converting enzyme inhibition), surgical (i.e. cardiac resynchronization therapy, left ventricular assist device implantation, and heart transplantation), and lifestyle (i.e. exercise training) interventions appropriate for patients with systolic HF.7,4143 Therefore, when CPX abnormalities are detected a review of the patient's clinical management strategy is recommended in order to determine whether titration of current interventions or the implementation of new interventions is warranted. In addition, standard ET variables should be included in the assessment as they may provide further information on clinical stability and prognosis. An abnormal haemodynamic and/or ECG response, as well as an abnormally low HR recovery (HRR) at 1 min post-ET and report of unusual dyspnoea (i.e. 4/4: severely difficult, patient cannot continue)17 as the primary subjective symptom eliciting test termination, provide further evidence of poor prognosis and greater disease severity.18,29,44,45

Heart failure with preserved ejection fraction and congenital heart disease

Several studies are now available that support the use of CPX for gauging the level of diastolic dysfunction and assessing prognosis in patients with HF-preserved ejection fraction (HF-PEF).4648 Embedded Image slope and EOV both appear to hold the prognostic value in patients with HF-PEF at a level comparable with that found in patients with systolic HF. Moreover, several investigations similarly support the prognostic importance of CPX in the congenital heart disease population.4951 Even so, additional research is needed in these patient populations to further elucidate the clinical value of CPX. At this time, the writing group recommends that the same reporting chart should be used for patients with systolic HF, HF-PEF, and congenital heart disease (see Appendix 2).

Hypertrophic cardiomyopathy

Cardiopulmonary ET has promising utility in regard to the assessment of patients with suspected/confirmed HCM. Ventilatory expired gas analysis during ET can be used to demarcate functional limitations, with diagnostic and prognostic implications. While the 2002 American College of Cardiology/American Heart Association ET guidelines52 cite HCM as a relative contraindication to ET, many investigators have subsequently highlighted that the technique is safe.5355 Not only can peak Embedded Image be used as criterion by which to guide HCM management, but it can also serve to distinguish left ventricular hypertrophy (LVH) associated with HCM from LVH stemming from relatively more innocuous aetiologies. Athletes may, for example, have physiological hypertrophy induced by physical activity. In this context, CPX can be applied to differentiate physiological hypertrophy from LVH in HCM simply on the basis of ET performance. While athletes achieve peak Embedded Image that typically exceed the predicted values, only 1.5% of HCM patients have peak Embedded Image exceeding the predicted values,56 providing a convenient way to help recognize HCM in young adults who may have LVH but who are asymptomatic and have not been diagnosed with the condition. Measures of ventilatory efficiency, specifically the Embedded Image slope and PETCO2, may also be valuable in patients with HCM as abnormalities in these variables have been associated with increased pulmonary pressures as a consequence of advanced LVH-induced diastolic dysfunction.57 Moreover, recent evidence indicates that aerobic capacity and ventilatory efficiency are prognostic markers in minimally symptomatic patients with obstructive HCM.58 As a provocative exercise stimulus, CPX also provides an important assessment of ECG and haemodynamics. A blunted (≤20 mmHg increase in systolic BP) or hypotensive (exercise systolic BP < resting values) exercise BP response is also common and indicates an increased risk of sudden death.59,60 Moreover, prognostic implications are even worse when abnormal haemodynamic responses are coupled to a low peak Embedded Image.61 While exercise-induced serious ventricular arrhythmias are comparatively rare, they may also be associated with high prognostic risks in some patients.62 The prognostic and diagnostic stratification chart for patients with confirmed or suspected HCM is provided in Appendix 3. Given the range of peak Embedded Imagevalues is likely to be wide in this patient population, a per cent-predicted value, which has recently demonstrated prognostic value in this population,58 should be included in the assessment. A progressive decline in per cent-predicted values, from green to red, is indicative of worsening disease severity and prognosis. Abnormalities in standard haemodynamic (i.e. systolic blood pressure) and ECG (i.e. onset of ventricular arrhythmias) variables, progressing to the red zone, are further indication of worsening disease severity and increased risk for adverse events. As values for the Embedded Image slope and PETCO2 progress from green to red, the likelihood of secondary pulmonary hypertension (PH), induced by HCM, is increased.

Unexplained exertional dyspnoea

Cardiopulmonary exercise testing possesses the unique ability to comprehensively assess the independent and integrated exertional responses of the CV and pulmonary systems. Moreover, the majority of current CPX systems have the capability to perform pulmonary function testing. Therefore, in patients presenting with unexplained exertional dyspnoea, CPX is considered an important assessment to determine the mechanism of exercise intolerance.1,52 When CPX is utilized for this indication, a primary goal should be to reproduce the patient's exertional symptoms in order to optimally detect any coinciding physiological abnormalities. The diagnostic stratification chart for patients with unexplained exertional dyspnoea is provided in Appendix 4. The Embedded Image slope, per cent-predicted peak Embedded Image, PETCO2, and the peak exercise VE/maximal voluntary ventilation (MVV) ratio are primary CPX variables for this assessment. Maximal voluntary ventilation should be directly measured prior to exercise as opposed to estimated using forced expiratory volume in 1 s (FEV1). Moreover, pulmonary function tests should be performed prior to and following CPX to determine FEV1 and peak expiratory flow (PEF).6367 Following CPX, FEV1, and PEF should be measured at 1, 3, 5, 7, 10, 15, and 20 min, as responses for these variables typically worsen several minutes into recovery when exercise induced bronchospasm (EIB) is present.67 In addition to the standard haemodynamic and ECG monitoring procedures, pulse oximetry (SpO2) should also be assessed at rest, throughout ET, and into recovery. Given the range of peak Embedded Image values is likely to be wide in this patient population, a per cent-predicted value should be included in the assessment. A progressive decline in per cent-predicted values, from green to red, indicates that the physiological mechanism resulting in exertional dyspnoea is having a greater impact on functional capacity. Abnormalities in the Embedded Image slope and PETCO2, particularly progressing to the red zone, indicate ventilation–perfusion abnormalities induced by pulmonary vasculopathy68,69 as a potential mechanism for exertional symptoms. Patients with ventilation–perfusion abnormalities may also present with a reduced SpO2, and, in such instances, this finding portends advanced pathophysiology. Isolated abnormalities (i.e. red zone) in VE/MVV, FEV1, and PEF are indicative of a pulmonary mechanism for the patient's unexplained exertional dyspnoea. For FEV1 and PEF responses in the red zone, EIB should be suspected and a bronchodilator trial may be warranted. While both FEV1 and PEF have been recommended for the assessment of EIB, FEV1 is frequently assessed in isolation.65,66 Thus, a decrease in FEV1 >15% post exercise, irrespective of the PEF response, is sufficient to suspect EIB.67 Detection of haemodynamic and/or ECG abnormalities that coincide with reproduced exertional dyspnoea are indicative of a CV mechanism for the patient's unexplained symptoms. Unique to CPX for this indication, a hypertensive response to exercise that coincides with exertional dyspnoea and exercise intolerance may be an early indicator of HF-PEF.70,71

Suspected or confirmed pulmonary arterial hypertension or secondary pulmonary hypertension

Although not currently a standard clinical indication for CPX, the body of evidence supporting the use of this form of ET in patients with suspected or confirmed PAH and secondary PH is growing at an impressive rate.68,69,7282 A key value of CPX in detecting potential pulmonary vasculopathy, or gauging disease severity once a diagnosis has been made, is the ability of this exercise approach to non-invasively quantify ventilation–perfusion abnormalities. Specifically, abnormalities in the Embedded Image slope and PETCO2 are strongly suggestive of pulmonary vasculopathy whose aetiology is either PAH or secondary PH as a consequence of other primary conditions such as HF, HCM, chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), or systemic connective tissue diseases. Moreover, there is emerging evidence to suggest key CPX variables portend the prognostic value in patients with PAH. The prognostic and diagnostic stratification chart for patients with suspected or confirmed PAH or secondary PH is provided in Appendix 5. Peak Embedded Image, the Embedded Image slope, and PETCO2 are primary CPX variables in patients with suspected or confirmed PAH or secondary PH. Patients suffering from pulmonary vasculopathy, regardless of the mechanism, typically present with significantly compromised aerobic capacity. Thus, reporting peak Embedded Image as an actual value, using the Weber classification system,30 is warranted. In those patients without a confirmed diagnosis, the likelihood of pulmonary vasculopathy increases as values for the Embedded Image slope and PETCO2 progress from green to red. In patients with a confirmed diagnosis of PAH/secondary PH, progressively worsening abnormalities of the aforementioned ventilatory efficiency variables as well as aerobic capacity are indicative of increasing disease severity. Moreover, worsening responses in these primary CPX variables are indicative of increased risk for adverse events. With respect to mode of testing, there is evidence to suggest ventilatory efficiency abnormalities are more pronounced during treadmill ET compared with cycle ergometry.83 Therefore, treadmill CPX may be optimal when assessing patients with suspected or confirmed pulmonary vasculopathy. In addition, patients with advanced PAH/secondary PH often present with an abnormal reduction in SpO2. Lastly, abnormal haemodynamic and/or ECG responses further compound concerns over increasing disease severity and prognosis in these patients.

Confirmed chronic obstructive pulmonary disease or interstitial lung disease

The literature supporting the use of CPX in patients with confirmed COPD or ILD is beginning to increase, producing compelling results in support of this form of ET for these patient populations. Several investigations have demonstrated that peak Embedded Image is predictive of adverse events in patients with COPD84,85 and ILD.86,87 Like patients with HF, a peak Embedded Image mL O2 • kg−1 • min−1 portends a particularly poor prognosis. The prognostic ability of peak Embedded Image in patients with pulmonary disease has led the American College of Chest Physicians to recommend that CPX be used pre-surgically in lung resection candidates to assess post-surgical risk.88 Initial evidence also indicates the Embedded Image slope is a significant post-surgical prognostic marker in patients with COPD undergoing lung resection.89 Additionally, the ability of CPX to gauge ventilatory efficiency is valuable in screening for secondary PH in patients with COPD and ILD.90,91 As the Embedded Image slope progressively increases and PETCO2 progressively decreases above and below their normal values, respectively, the presence of secondary PH becomes more likely. The prognostic and diagnostic stratification chart for patients with COPD and ILD is provided in Appendix 6. Peak Embedded Image, the Embedded Image slope, and PETCO2 are primary CPX variables for both COPD and ILD patients. As values for these variables progress to the red zone, there is an increased risk for adverse events and greater likelihood of secondary PH. Additionally, standard exercise variables progressing to the red zone compound the concern for poor prognosis in these patients.

Suspected myocardial ischaemia

Standard incremental ET procedures are a well-accepted and valuable clinical assessment tool in patients at high risk for myocardial ischaemia.6,52,92 The use of ventilatory expired gas analysis for patients undergoing ET for suspected myocardial ischaemia is not commonplace in the clinical setting at this time. In recent years, however, several investigations have demonstrated the potential diagnostic utility of CPX in this setting.93,94 Recent studies have found that the real-time change in the O2 pulse and Embedded Image trajectories are most valuable when using CPX to assess exercise-induced myocardial ischaemia. Under normal physiological conditions, both of these relationships progressively rise during maximal ET. However, left-ventricular dysfunction induced by myocardial ischaemia causes both the O2 pulse and Embedded Image trajectories to prematurely flatten or decline (see Figure 1). In a landmark study, Belardinelli et al.95 performed CPX in 202 patients with a confirmed diagnosis of coronary heart disease (CHD), using 2-day stress/rest-gated SPECT myocardial scintigraphy as the gold standard for myocardial ischaemia. Using logistic regression, flattening of the O2 pulse and Embedded Image trajectories were independent predictors of exercise-induced myocardial ischaemia. The sensitivity and specificity for O2 pulse + Embedded Image flattening as criteria for exercise-induced myocardial ischaemia were 87 and 74%, respectively. Comparatively, ECG criteria for exercise-induced myocardial ischaemia, defined as the onset of 1.0 mm horizontal ST-segment depression in at least two adjacent leads, produced a sensitivity and specificity of 46 and 66%, respectively. Of particular note, the addition of O2 pulse and Embedded Image trajectory assessments helped to rule out ischaemia in a significant portion of individuals for whom the ECG was falsely positive. As a technical note, the majority of investigations validating the clinical applications of CPX for patients with suspected myocardial ischaemia to this point, including the landmark investigation by Belardinelli et al.,95 used a lower extremity bicycle ergometry as the mode of testing. Thus, additional research should be conducted to determine whether the diagnostic utility of CPX for myocardial ischaemia is present when a treadmill is the testing mode. The diagnostic stratification chart for patients with suspected myocardial ischaemia is provided in Appendix 7. Assessment of the O2 pulse and Embedded Image trajectories are primary CPX variables. As values for these variables progress to the red zone, the likelihood of exercise-induced myocardial ischaemia increases. Given that the range of peak Embedded Imagevalues is likely to be wide in patients undergoing CPX for this indication, a per cent-predicted value should be included in the assessment. A progressive decline in per cent-predicted values, from green to red, is indicative of poorer aerobic fitness and possibly increased coronary artery disease severity. Previous research has demonstrated lower per cent-predicted aerobic fitness values to be indicative of poor prognosis.96 As with all ET procedures, standard haemodynamic and ECG variables should be assessed in patients with suspected myocardial ischaemia. Abnormalities in these measures progressing to the red zone further increase the likelihood of exercise-induced myocardial ischaemia and provide prognostic insight.29 Lastly, evidence suggests patients with suspected myocardial ischaemia who report unusual dyspnoea (i.e. 4/4: severely difficult, patient cannot continue)17 as the primary reason for exercise limitations have a poorer prognosis compared with those whose primary limiting symptom is lower extremity fatigue or angina.14 While research demonstrating the value of CPX in this area is promising, additional investigations are needed to further substantiate CPX for this purpose, particularly in cohorts with suspected myocardial ischaemia and no prior workup bias.

Suspected mitochondrial myopathy

A number of genetic abnormalities exist which can lead to diminished CRF and a host of other exertional abnormalities uniquely captured by CPX.22,97 The degree of impairment in peak Embedded Image appears to correlate to the severity of genetic mutation.22,98 Moreover, patients with mitochondrial myopathies have an elevated Embedded Image ratio at peak exercise, as the ventilatory cost of Embedded Image dramatically rises due to aerobic inefficiency by affected skeletal muscle. The ability to non-invasively quantify Q during CPX in an accurate manner is now possible through foreign gas rebreathing methods.1 Using this technique, the relationship between Q (y-axis) and Embedded Image (x-axis) during ET are plotted, generating a slope value. In normal circumstances, where O2 utilization and delivery are well matched, the Embedded Image slope is 5 L min−1. In subjects with mitochondrial myopathies, this slope is much higher as oxygen delivery far exceeds the capacity for utilization.22 The diagnostic stratification chart for patients with suspected mitochondrial myopathy is provided in Appendix 8. The assessment of the Embedded Image slope and peak Embedded Image are primary CPX variables. As values for these variables progress to the red zone, the likelihood of a mitochondrial myopathy increases. Moreover, the degree of abnormality in the Embedded Image slope and peak Embedded Image response is indicative of the degree of mitochondrial mutation load. Given the range of peak Embedded Image values is likely to be wide in patients undergoing CPX for this indication, a per cent-predicted value should be included in the assessment. A progressive decline in per cent-predicted values, from green to red, when coinciding with an abnormal Embedded Image slope and peak Embedded Image, is likewise indicative of an increasingly higher mitochondrial mutation load. When these variables are abnormal, a muscle biopsy would be warranted to obtain a definitive diagnosis. Additionally, standard haemodynamic and ECG variables should be assessed in patients with suspected mitochondrial myopathy, as abnormalities in these measures are universally indicative of CV abnormalities and increased adverse event risk.29

Directions for future research

The current statement provides recommendations for CPX data interpretation based on currently available scientific evidence and expert consensus. However, there are other CPX variables that may emerge as clinically important measures in a number of the patient populations described herein. Examples of CPX variables demonstrating the potential value are the oxygen uptake efficiency slope,99101 circulatory power102 and Embedded Image onset103,104 and recovery105 kinetics. Moreover, additional research is needed to further increase support for the use of CPX in certain patient populations as previously mentioned. Additional investigations into the value of CPX in females also seem warranted across all patient populations that would benefit from this form of ET. Lastly, future investigations are needed to determine whether other patient populations would benefit from CPX as a component of their clinical assessment. For example, there is some initial data to indicate CPX may provide valuable information in patients with atrial fibrillation, a condition associated with ventilatory and functional abnormalities.106,107 This writing group encourages continued research into the clinical utility of CPX across all patient populations where a viable case can be made for this form of ET, addressing specific questions in need of further analysis. Future investigations in this area will lead to additional refinement of CPX utilization and data interpretation as well as improve the clinical value of this assessment technique.

Conclusions

Cardiopulmonary exercise testing is well recognized as the gold standard aerobic ET assessment. The use of CPX is well established in the clinical setting for both patients with systolic HF, undergoing a pre-transplant assessment, and individuals with unexplained exertional dyspnea.6,52 The evidence supporting the use of CPX in patients with confirmed or suspected PAH and secondary PH is also rapidly expanding and a strong case for the application of this ET assessment in this population can now be made. There is also emerging evidence to demonstrate CPX elicits clinically valuable information in a number of other patient populations, which are described in this document. Irrespective of the reason for the ET assessment, the utility of CPX currently suffers from an inability to easily interpret the most useful information in a way that is evidence based and specific to test indication. The present document attempts to rectify this issue by coalescing expert opinion and current scientific evidence and creating easily interpretable CPX charts that are indication specific. It is the hope of the writing group that this document will expand the appropriate use of CPX by simplifying data interpretation, thereby increasing the clinical value of the data obtained.

Appendix

View this table:
Appendix 1:

Universal CPX reporting form (complete all boxes that apply for given ET indication)

Exercise modality: [ ] Treadmill [ ] Lower extremity ergometer
Protocol:
Peak VO2 (mL O2•kg−1•min−1)Per cent-predicted peak VO2 (%)aVE/VCO2 slope
VO2 at VT (mL O2•kg−1•min−1)Peak REREOV [ ] Yes [ ] No
PETCO2 (mmHg)VE/VO2 at peak ETΔQ/ΔVO2b
Resting:
Increase during ET:
VE/MVVc: PEF (L/min): Pre-ET Post-ET
O2 pulse trajectoryd
[ ] Continual rise throughout ET [ ] Early and sustained plateau [ ] Decline
ΔVO2/ΔW trajectoryd
[ ] Continual rise throughout ET [ ] Early and sustained plateau [ ] Decline
Resting HR (b.p.m.)Resting BP (mmHg)Resting pulse oximetry (%)
Peak HR (b.p.m.)Peak BP (mmHg)Peak pulse oximetry (%)
Percent of age-predicted maximal HReMaximal workload
HRR at 1 min (beats)[ ] Treadmill speed/grade:
[ ] Cycler ergometer Watts:
ECG criteriaECG description
[ ] No arrhythmias/Ectopy/ST segment changes
[ ] Arrhythmias/Ectopy/ST segment changes: not exercise limiting
[ ] Arrhythmias/Ectopy/ST segment changes: exercise limiting
Subjective symptoms (check box for primary termination criteria)
RPE [ ] Angina [ ] Dyspnoea [ ]
Additional notes
  • CPX, cardiopulmonary exercise testing; ET, exercise testing; VO2, oxygen consumption; VT, ventilator threshold; RER, respiratory exchange ratio; VE/VCO2, minute ventilation/carbon dioxide production; EOV, exercise oscillatory ventilation; PETCO2, partial pressure of end-tidal carbon dioxide production; VE/VO2, minute ventilation/oxygen consumption; VE/MVV, peak minute ventilation/maximal voluntary ventilation; ΔQ/ΔVO2, change in cardiac output/change in oxygen consumption; PEF, peak expiratory flow; O2, oxygen; ΔVO2/ΔW, change in oxygen consumption/change in Watts; HR, heart rate; BP, blood pressure; HRR, heart rate recovery; ECG, electrocardiogram; RPE, rating of perceived exertion

  • aUse equations proposed by Wasserman.

  • bRequires additional equipment of assess Q response to exercise through non-invasive rebreathing technique.

  • cDirectly measure MVV at baseline.

  • dRequires O2 pulse and ΔVO2/ΔW plot from initiation to end of ET. If these variables required for assessment, electronically braked cycle ergometer should be used for testing.

  • eUse equation: (peak HR/220-age) * 100.

View this table:
Appendix 2:

Prognostic and diagnostic stratification for patients with HF

Primary CPX variables
VE/VCO2 slopePeak VO2aEOVPETCO2
Ventilatory class IWeber class ANot presentResting PETCO2
VE/VCO2 slope <30.0Peak VO2 >20.0 mL O2•kg−1•min−1≥33.0 mmHg
Ventilatory class IIWeber class B3–8 mmHg increase during ET
VE/VCO2 slope 30.0–35.9Peak VO2 = 16.0–20.0 mL O2•kg−1•min−1
Ventilatory class IIIWeber class CPresentResting PETCO2
VE/VCO2 slope 36.0–44.9Peak VO2 = 10.0–15.9 mL O2•kg−1•min−1<33.0 mmHg
Ventilatory class IVWeber class D<3 mmHg increase during exercise
VE/VCO2 slope ≥45.0Peak VO2 <10.0 mL O2•kg−1•min−1
Standard ET variables
HaemodynamicsECGHRR
Rise in systolic BP during ETNo sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recovery>12 beats at 1 min recovery
Flat systolic BP response during exerciseAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination≤12 beats at 1 min recovery
Drop in systolic BP during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Patient reason for test termination
Lower extremity muscle fatigueAnginaDyspnoea
Interpretation
• All variables in green: excellent prognosis in next 1–4 years (≥90% event free)
 – Maintain medical management and retest in 4 years.
• Greater number of CPX and standard ET variables in red/yellow/orange indicative of progressively worse prognosis.
 – All CPX variables in red: risk for major adverse event extremely high in next 1–4 years (>50%).
• Greater number of CPX and standard ET variables in red/yellow/orange indicative of increasing HF disease severity.
 – All CPX variables in red: expect significantly diminished cardiac output, elevated neurohormones, higher potential for secondary PH.
• Greater number of CPX and standard ET variables in red/yellow/orange warrants strong consideration of more aggressive medical management and surgical options.
  • VE/VCO2, minute ventilation/carbon dioxide production; VO2, oxygen consumption; EOV, exercise oscillatory ventilation; PETCO2, partial pressure of end-tidal carbon dioxide; BP, blood pressure; CPX, cardiopulmonary exercise test; ECG, electrocardiogram; ET, exercise test; HRR, heart rate recovery; RER, respiratory exchange ratio.

  • aPeak VO2 valid if peak RER is at least 1.00 or test terminated secondary to abnormal haemodynamic or ECG exercise response.

View this table:
Appendix 3:

Prognostic and diagnostic stratification for patients with confirmed or suspected HCM

Primary CPX variables
VE/VCO2 slopePer cent-predicted peak VO2aPETCO2 apex during ETb
Ventilatory class I≥100% predicted>37 mmHg
VE/VCO2 slope <30.0
Ventilatory class II75–99% predicted36–30 mmHg
VE/VCO2 slope 30.0–35.9
Ventilatory class III50–75% predicted29–20 mmHg
VE/VCO2 slope 36.0–44.9
Ventilatory class IV<50% predicted<20 mmHg
VE/VCO2 slope ≥45.0
Standard ET variables
HaemodynamicsECG
Rise in systolic BP during ETNo sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recovery
Flat systolic BP response during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination
Drop in systolic BP during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Interpretation
• Progressively higher VE/VCO2 slope and lower per cent-predicted peak VO2 and peak PETCO2 indicative of greater HCM severity.
 – CPX variables progressing from yellow to orange to red increase the likelihood of increased pulmonary pressure.
• Haemodynamic and ECG responses in yellow and red indicative of increasing risk for sudden cardiac death.
  • VE/VCO2, minute ventilation/CO2 production; VO2, O2 consumption; PETCO2 apex, partial pressure of end-tidal CO2; BP, blood pressure; CPX, cardiopulmonary exercise test; ECG, electrocardiogram; ET, exercise test; HCM, hypertrophic cardiomyopathy; VT, ventilatory threshold.

  • aPeak VO2 valid if peak respiratory exchange ratio is at least 1.00 or test terminated secondary to abnormal haemodynamic or ECG exercise response. Per cent-predicted values derived from formulas proposed by Wasserman.

  • bPETCO2 apex is achieved at submaximal levels during a progressive exercise test; typically immediately proceeds VT.

View this table:
Appendix 4:

Diagnostic stratification for patients with unexplained exertional dyspnoea

Primary CPX variables
VE/VCO2 slopePercent-predicted peak VO2aPETCO2VE/MVVb
Ventilatory class I≥100% predictedResting PETCO2 36–42 mmHg>0.80
VE/VCO2 slope <30.0
Ventilatory class II75–99% predicted3–8 mmHg increase during ET
VE/VCO2 slope 30.0–35.9
Ventilatory class III50–75% predictedResting PETCO2 <36 mmHg <3 mmHg increase during ET≤0.80
VE/VCO2 slope 36.0–44.9
Ventilatory class IV<50% predicted
VE/VCO2 slope ≥45.0
Primary PFT variables: FEV1 and PEFc
No change from pre- to post-CPX≥15% reduction from pre- to post-CPX
Standard ET variables
HaemodynamicsECGPulse oximetry
Rise in systolic BP during ET: 10 mmHg/3.5 mL O2•kg−1•min−1 increase in VO2No sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recoveryNo change in SpO2 from baseline
Flat response or drop in systolic BP during ET OrAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination>5% decrease in SpO2 from baseline
Excessive rise in systolic BP during exercise: ≥20 mmHg/3.5 mL O2•kg−1•min−1 increase in VO2Altered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Interpretation
• Progression of per cent predicted peak VO2 from green to red reflects degree of functional impairment irrespective of mechanism.
• As VE/VCO2 slope progresses from yellow to orange to red and PETCO2 progresses to red, consider exertion-induced increase in pulmonary pressure as a mechanism.
• Pulse oximetry progression to red indicative of ventilation-perfusion mismatch.
• VE/MVV, FEV1, and PEF in red indicative of pulmonary mechanism; worsening FEV1 and PEF response through first several minutes of recovery suggestive of EIB; FEV1 response in the red, irrespective of PEF response, also suggestive of EIB.
• Haemodynamic and/or ECG response in red indicative of CV mechanism.
  • VE/VCO2, minute ventilation/CO2 production; VO2, O2 consumption; PETCO2, partial pressure of end-tidal CO2; VE/MVV, minute ventilation at peak exercise/maximal voluntary ventilation (maximal voluntary ventilation should be directly measured prior to ET); PFT, pulmonary function test; FEV1, forced expiratory volume in one second; PEF, peak expiratory flow; BP, blood pressure; CPX, cardiopulmonary exercise test; CV, cardiovascular; ECG, electrocardiogram; ET, exercise test; RER, respiratory exchange ratio; SpO2, saturation of peripheral O2; EIB, exercise induced bronchospasm.

  • aPeak VO2 valid if peak RER is at least 1.00 or test terminated secondary to abnormal haemodynamic or ECG exercise response. Percent-predicted values derived from formulas proposed by Wasserman.

  • bMVV should be directly measured prior to CPX; the majority of CPX systems allow for MVV measurement.

  • cFollowing CPX, measurement of FEV1 and PEF should be conducted at 1, 3, 5, 7, 10, 15, and 20 min.

View this table:
Appendix 5:

Prognostic and diagnostic stratification for patients with suspected or confirmed PAH/secondary PH

Primary CPX variables
VE/VCO2 slopePeak VO2aPETCO2 apex during exerciseb
Ventilatory class IWeber class A>37 mmHg
VE/VCO2 slope <30.0Peak VO2 > 20.0 mL O2•kg−1•min−1
Ventilatory class IIWeber class B36–30 mmHg
VE/VCO2 slope 30.0–35.9Peak VO2 = 16.0–20.0 mL O2•kg−1•min−1
Ventilatory class IIIWeber class C29–20 mmHg
VE/VCO2 slope 36.0–44.9Peak VO2 = 10.0–15.9 mL O2•kg−1•min−1
Ventilatory class IVWeber class D<20 mmHg
VE/VCO2 slope ≥45.0Peak VO2 <10.0 mL O2•kg−1•min−1
Standard ET variables
HaemodynamicsECGPulse oximetry
Rise in systolic BP during ETNo sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recoveryNo change in SpO2 from baseline
Flat systolic BP response during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination>5% decrease in SpO2 from baseline
Drop in systolic BP during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Interpretation
• All variables in green: indicative of good prognosis.
 – Maintain medical management and retest in 4 years.
• Greater number of CPX and standard ET variables in red/yellow/orange indicative of progressively worse prognosis.
 – All CPX variables in red: risk for major adverse event extremely high in next 1–4 years.
• Greater number of CPX and standard ET variables in red/yellow/orange indicative of increasing severity of pulmonary vasculopathy.
 – All CPX variables in red: expect significantly increased pulmonary arterial pressure.
• Greater number of CPX and standard ET variables in red/yellow/orange warrants strong consideration of more aggressive medical management.
  • VE/VCO2, minute ventilation/CO2 production; VO2, O2 consumption, PETCO2, partial pressure of end-tidal CO2; BP, blood pressure; CPX, cardiopulmonary exercise test; ECG, electrocardiogram; ET, exercise test; PAH, pulmonary arterial hypertension; PH, pulmonary hypertension; RER, respiratory exchange ratio; SpO2, saturation of peripheral O2; VT, ventilatory threshold.

  • aPeak VO2 valid if peak RER is at least 1.00 or test terminated secondary to abnormal haemodynamic or ECG exercise response.

  • bPETCO2 apex achieved at submaximal levels; typically immediately proceeds VT.

View this table:
Appendix 6:

Prognostic and diagnostic stratification for patients with COPD or ILD

VE/VCO2 slopePeak VO2aPETCO2
Ventilatory class IWeber class AResting PETCO2 ≥33.0 mmHg
VE/VCO2 slope <30.0Peak VO2 >20.0 mL O2•kg−1•min−1
Ventilatory class IIWeber class B3–8 mmHg increase during ET
VE/VCO2 slope 30.0–35.9Peak VO2 = 16.0–20.0 mL O2•kg−1•min−1
Ventilatory class IIIWeber class CResting PETCO2 <33.0 mmHg
VE/VCO2 slope 36.0–44.9Peak VO2 = 10.0–15.9 mL O2•kg−1•min−1
Ventilatory class IVWeber class D3–8 mmHg increase during ET
VE/VCO2 slope ≥45.0Peak VO2 <10.0 mL O2•kg−1•min−1
Standard ET variables
HaemodynamicsECGHRRPulse oximetry
Rise in systolic BP during ETNo sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recovery>12 beats at 1 min recoveryNo change in SpO2 from baseline
Flat systolic BP response during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination≤12 beats at 1 min recovery>5% decrease in SpO2 from baseline
Drop in systolic BP during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Interpretation
• All variables in green: excellent prognosis in next 1–4 years.
 – Maintain medical management and retest in 4 years.
• Greater number of CPX and standard exercise test variables in red/yellow/orange indicative of progressively worse prognosis.
 – All CPX variables in red: risk for major adverse event extremely high in next 1–4
• Greater number of CPX and standard ET variables in red/yellow/orange indicative of increasing interstitial lung disease severity.
 – As VE/VCO2 slope and PETCO2 progress to red, likelihood of secondary PH increases.
• Greater number of CPX and standard ET variables in red/yellow/orange warrants strong consideration of more aggressive medical management and surgical options.
  • VE/VCO2, minute ventilation/CO2 production; VO2, oxygen Consumption; PETCO2: partial pressure of end-tidal CO2; BP, blood pressure; COPD, chronic obstructive pulmonary disease; CPX, cardiopulmonary exercise test; ECG, electrocardiogram; ET, exercise test; HRR, heart rate recovery; ILD, interstitial lung disease; PH, pulmonary hypertension; RER, respiratory exchange ratio; SpO2, saturation of peripheral O2.

  • aPeak VO2 valid if peak RER is at least 1.00 or test terminated secondary to abnormal haemodynamic or ECG exercise response.

View this table:
Appendix 7:

Diagnostic stratification for patients with suspected myocardial ischaemia

Primary CPX variables
O2 pulse trajectorybPer cent-predicted peak VO2aΔVO2/ΔW trajectoryb
Continual rise throughout ET with possible plateau approaching maximal exertion≥100% predictedContinual rise throughout ET
Early and sustained plateau75–99% predictedEarly and sustained plateau
50–75% predicted
Early plateau then decline<50% predictedEarly plateau then decline
Standard exercise test variables
HaemodynamicsECG
Rise in systolic BP during ETNo sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recovery
Flat systolic BP response during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination
Drop in systolic BP during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Patient reason for test termination
Lower extremity muscle fatigueAnginaDyspnoea
Interpretation
• Progression of per cent-predicted peak VO2 from green to red indicative of progressively higher level of ischaemia and functional decline.
• O2 pulse and ΔVO2/ΔW trajectory progressing to red indicative of myocardial ischaemia in appropriately screened patients (i.e. baseline signs/symptoms/risk factors suggesting increased coronary artery disease risk).
• Haemodynamic and ECG responses in yellow and red indicative of abnormal exercise response and further support myocardial ischemia in appropriately screened patients (i.e. baseline signs/symptoms/risk factors suggesting increased CHD risk).
  • O2 pulse, oxygen pulse; VO2, oxygen consumption; ΔVO2/ΔW, change in oxygen consumption/change in Watts; BP, blood pressure; COPD, chronic obstructive pulmonary disease; CPX, cardiopulmonary exercise test; ECG, electrocardiogram; ET, exercise test; ILD, interstitial lung disease; PH, pulmonary hypertension; RER, respiratory exchange ratio.

  • aPer cent-predicted peak VO2 valid if peak RER is at least 1.00 or test terminated secondary to abnormal hemodynamic or ECG exercise response. Per cent-predicted values derived from formulas proposed by Wasserman

  • bRequires O2 pulse and ΔVO2/ΔW plot from initiation to end of exercise test. If these variables required for assessment, electronically braked cycle ergometer should be used for testing.

View this table:
Appendix 8:

Diagnostic stratification for patients with suspected mitochondrial myopathy

Primary CPX variables
ΔQ/ΔVO2Per cent-predicted peak VO2aPeak VE/VO2
≈5≥100% predicted≈40
75–99% predicted50 = upper limit of normal
≥750–75% predicted>50
<50% predicted
Standard ET variables
HaemodynamicsECG
Rise in systolic BP during ETNo sustained arrhythmias, ectopic foci, and/or ST segment changes during ET and/or in recovery
Flat systolic BP response during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: did not lead to test termination
Drop in systolic BP during ETAltered rhythm, ectopic foci, and or ST segment changes during ET and/or in recovery: led to test termination
Interpretation
• Progression of per cent-predicted peak VO2 from green to red indicative of progressively higher level of mitochondrial dysfunction.
• ΔQ/ΔVO2 and peak VE/VO2 in red indicative of mitochondrial myopathy; consider muscle biopsy to obtain definitive diagnosis.
• Although not diagnostic for mitochondrial myopathy, haemodynamic and ECG responses in yellow and red universally indicative of abnormal ET response.
  • ΔQ/ΔVO2, change in cardiac output/change in O2 consumption; measurement requires additional equipment of assess Q response to ET through non-invasive rebreathing technique; VO2, O2 consumption; VE/VO2, minute ventilation/O2 consumption; BP, blood pressure; CPX, cardiopulmonary exercise test; ECG, electrocardiogram; ET, exercise test; RER, respiratory exchange ratio.

  • aPer cent-predicted peak VO2 valid if peak RER is at least 1.00 or ET terminated secondary to abnormal haemodynamic or ECG exercise response. Per cent-predicted values derived from formulas proposed by Wasserman.

References