European Heart Journal Advance Access originally published online on October 9, 2006
European Heart Journal 2006 27(21):2609-2610; doi:10.1093/eurheartj/ehl292
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Coronary flow reserve in dilated cardiomyopathy: an important pathophysiological tool to be considered among, but not instead of, other well-established prognostic factors: reply
CNR, Institute of Clinical Physiology
Via. G. Moruzzi, 1
56124 Pisa
Italy
Tel/fax: +39 050 315 2374
E-mail address: rosas{at}ifc.cnr.it
Cardiology Division
Umberto I° Hospital
Mestre-Venice
Italy
We thank Dr De Gregorio for the interest in our work. The cut-off value employed, 2, is a widely accepted criterion of normality as extensively discussed with review of the existing literature.1 Different cut-off values could have been employed and a receiver operating characteristic analysis was performed but was not considered an appropriate approach by the statistical reviewer because of the censored nature of the endpoint. The cut-off value that best related to the occurrence of spontaneous events was 1.8 and consistent with our previous reports addressing the value of prognostic power of coronary flow reverse (CFR).2 These observations should be put into a wider framework of test use and interpretation. In fact, the presence/absence of disease applied to diagnostic testing might be very fallacious when the issue is prognosis. For instance, in coronary artery disease, highly sensitive tests that work finely even in the identification of minor vessel disease do not have a prognostic counterpart as minor forms of coronary artery disease are not life-threatening. In the field of stress echocardiography, this problem has been clearly demonstrated when, in order to increase test sensitivity, both for dobutamine and dipyridamole atropine was added.3 Sensitivity increased but the subset of patients with test positivity after atropine did not have any difference in survival when compared with the subset with a negative test.4 We could have employed a more aggressive ‘diagnostic’ approach also in this set of patients by using cut-off values higher than 2.5, but prognostic testing needs a more conservative approach.5 In the ‘fisherman's approach’, proposed by Ostojic from Belgrade, we need a net with big holes to catch the bigger fish of disease giving prognostic troubles.3 The holes will be smaller with aggressive testing giving optimal diagnostic values. What works efficiently in diagnostic testing could be translated into a poor prognostic test at least in the short–medium run. In our patient population, 14 patients had a CFR >2.5 and they had a 80% survival rate. We agree that CFR, in this set of patients, cannot be considered the sole parameter to be evaluated but is one among others able to risk stratify patients identifying those needing a more aggressive approach due to the severity of the disease. As reported in the univariate and multivariable analyses, several parameters were able to identify patients at risk of experiencing spontaneous events. The multivariable analysis reported in the results section of the manuscript identified severity of mitral insufficiency, abnormal CFR, and resting WMSI as independent predictors of survival. In the conclusions of the manuscript, there was no intention of implying that more conventional clinical and echo parameters in the evaluation of patients with non-ischaemic dilated cardiomyopathy should be discarded. The routine use of CFR assessment allowed us to obtain interesting pathophysiological information that have a practical impact, transferable into the clinical arena, at reasonable costs and minimizing acute and long-term risks. We fully agree with Dr De Gregorio that CFR is a complementary parameter easily obtained during vasodilatory stress echo along with ejection fraction, volumes, mitral regurgitation, and regional function both at rest and at peak stress. The worst mistake that a clinical cardiologist can make is to view these novel parameters entering the prognostic scenario in an agonistic-competitive view with old, time-honoured parameters of established usefulness.5 We thank De Gregorio for reminding us this obvious but frequently forgotten fact. Altogether, these parameters provide a powerful means of stratification just in one sitting during a single exam.6
References
- Rigo F. (2005) Coronary flow reserve in stress-echo lab. From pathophysiologic toy to diagnostic tool. Cardiovasc Ultrasound 3:8.[CrossRef][Medline]
- Rigo F, Cortigiani L, Pasanisi E, Richieri M, Cutaia V, Celestre M, Raviele A, Picano E. (2005) The additional prognostic value of coronary flow reserve on left anterior descending artery in patients with negative stress echo by wall motion criteria. A transthoracic vasodilator stress echo study. Am Heart J 149:684–689.
- Nedeljkovic I, Ostojic M, Beleslin B, Djordjevic-Dikic A, Stepanovic J, Nedeljkovic M, Stojkovic S, Stankovic G, Saponjski J, Petrasinovic Z, Giga V, Mitrovic P. (2006) Comparison of exercise, dobutamine-atropine and dipyridamole-atropine stress echocardiography in detecting coronary artery disease. Cardiovasc Ultrasound 4:22.[CrossRef][Medline]
- Pingitore A, Picano E, Varga A, Gigli G, Cortigiani L, Previtali M, Minardi G, Colosso MQ, Lowenstein J, Mathias W Jr, Landi P. (1999) Prognostic value of pharmacological stress echocardiography in patients with known or suspected coronary artery disease: a prospective, large-scale, multicenter, head-to-head comparison between dipyridamole and dobutamine test. Echo-Persantine International Cooperative (EPIC) and Echo-Dobutamine International Cooperative (EDIC) Study Groups. J Am Coll Cardiol 34:1769–1777.
[Abstract/Free Full Text] - Picano E. (2004) Sustainability of medical imaging. (Review). BMJ 328:578–580.
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