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Guidelines on the management of stable angina pectoris: reply

Kim Fox, Caroline Daly
DOI: http://dx.doi.org/10.1093/eurheartj/ehl258 2606-2607 First published online: 6 October 2006

We thank the authors for the opportunity to discuss in further detail the rationale behind the task force's decision to give exercise perfusion imaging a Class I indication as the initial diagnostic test in assessment of patients with angina and left bundle branch block (LBBB).

As pointed out, there are data that suggest superior diagnostic accuracy of vasodilator stress (but not dobutamine stress)1 compared with exercise stress scintigraphy in predicting the presence of obstructive disease of the left anterior descending (LAD) artery. Methodological weaknesses of some of the individual studies apart, e.g. small size,2 lack of direct comparison between exercise and pharmacological stress,2 and work up bias, a major problem with the interpretation of the results is that they do not include the clinical and haemodynamic variables from exercise in predicting the presence or absence of coronary disease. The diagnostic accuracy of the test is determined solely by the correlation of perfusion abnormalities in response to stress to the presence of coronary obstruction. Earlier studies do not evaluate associated wall thickening, as is possible with modern gated SPECT and which may be useful in reducing artefactual perfusion abnormalities.3 In this context, without the benefit of including haemodynamic and clinical variables, reported sensitivity of 100% for the prediction of LAD stenoses and specificity as high as 56%, with no reduction in the sensitivity or specificity for the detection of coronary stenoses in other vessels, seems reasonable.4,5

Most importantly however, the task force opines that pharmacological stress does not offer the clinician the wealth of information afforded by exercise testing in terms of functional capacity, time to angina, and the associated diagnostic and prognostic information therein. Such small studies as have compared exercise and vasodilator stress in the diagnostic assessment of chest pain in the presence of LBBB have not compared the techniques in terms of predicting prognosis. However, multiple studies have demonstrated that the combination of exercise variables with perfusion data improves the diagnostic performance of the test, with both parts of the test (exercise and perfusion) adding independent incremental prognostic information to each other.6

References

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