LETTER TO THE EDITOR
Reply
Hans-Marc J. Siebelink, MD, PhDa,
Paul K. Blanksma, MD, PhDa,
Harry J. G. M. Crijns, MD, PhDa,
Jeroen J. Bax, MD, PhDa,
Ad J. van Boven, MD, PhDa,
Tsjerk Kingma, MSca,
D. Albertus Piers, MD, PhDa,
Jan Pruim, MD, PhDa,
Piet L. Jager, MD, PhDa,
Willem Vaalburg, PhDa and
Ernst E. van der Wall, MD, PhD, FACCa
a Thorax Center, Department of Cardiology, Groningen University Hospital, P.O. Box 30001, 9700 RB Groningen, The Netherlands
h.j.siebelink{at}thorax.azg.nl
Beanlands and colleagues make some interesting remarks on which we would like to comment.
The purpose of our study was to evaluate in a prospective, blinded, and randomized clinical setting what effect positron emission tomography (PET) and single-photon emission computed tomographic (SPECT) imaging had on patient management (revascularization or drug treatment) and clinical outcome (cardiac events) in patients in whom jeopardized myocardium was suspected (1). Therefore, the population in our study resembles the everyday clinical practice of 103 patients who are candidates for viability testing. In our population the event rate was 23%, and there was no significant difference in patient management and clinical outcome between PET and SPECT-based patient management. As Beanlands and colleagues state, the clinical relevance of observed differences often remains arbitrary and may vary with different patient populations (e.g., severe left ventricular [LV] dysfunction). However, we believe that in our study the observed differences in cardiac event rate were not clinically meaningful, because 19,250 patients should have been included to reach a significant p value.
Concerning the patient population in our study, we are well aware of the fact that most patients (65%) had mild to moderate LV dysfunction. Therefore, conclusions on patients with severe LV dysfunction should be interpreted with caution, although our prospective, blinded and randomized study indicates that clinical outcome might not be different between PET and SPECT-based management in this category.
At the time we designed the study we used the most appropriate criteria for the detection of jeopardized myocardium (1). Obviously, during the study we were not able to incorporate new insights concerning detection of jeopardized myocardium. If more patients with severe LV dysfunction were included in our study we can only speculate whether this would have led to increased discrepancies between PET and SPECT. It also remains speculative whether these discrepancies would have resulted in different management and different clinical outcome.
Opposite to what Beanlands and colleagues suggest, we believe that our study contains no selection bias toward revascularization, but just addresses the practical clinical question: revascularize or not, depending on the amount of jeopardized myocardium. The intended revascularization in our study was planned with an urgency-based schedule. We agree with Beanlands and colleagues that this could reduce some of the benefits of revascularization when revascularization is delayed (2), but the urgency-based schedule illustrates the clinical reality in an HMO-oriented health care system.
We fully agree with Beanlands and colleagues that larger randomized, controlled clinical trials are needed, and we are pleased to hear that some are underway. In our opinion these studies should address the role of various viability techniques (PET, SPECT, echocardiography, magnetic resonance imaging) in different patient populations (mild, moderate, severe LV dysfunction) and their cost-effectiveness. Preferably, these studies should be conducted in a blinded fashion to prevent selection biases, as we have demonstrated (1). Moreover, we believe these studies should focus on patient management and clinical outcome, because that is what is most important to patients in the everyday clinical practice (3).
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References
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1. Siebelink H-MJ, Blanksma PK, Crijns HJGM, et al. No difference in cardiac event-free survival between positron emission tomography–guided and single-photon emission computed tomography–guided patient management: a prospective, randomized comparison of patients with suspicion of jeopardized myocardium. J Am Coll Cardiol. 2001;37:81–88[Abstract/Free Full Text]
2. Beanlands RS, Hendry PJ, Masters RG, deKemp RA, Woodend K, Ruddy TD. Delay in revascularization is associated with increased mortality rate in patients with severe left ventricular dysfunction and viable myocardium on fluorine 18-fluorodeoxyglucose positron emission tomography imaging. Circulation. 1998;98:1151–1156[Free Full Text]
3. Udelson JE. Testing our tests: surrogate end points versus driving patient management and outcomes. J Am Coll Cardiol. 2001;37:89–92[Free Full Text]
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