CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Karen Okrainec, MSc and
Mark J. Eisenberg, MD, MPH, FACC*
* Divisions of Cardiology and Clinical Epidemiology, Jewish General Hospital, McGill University, 3755 Cote Ste. Catherine Road, Suite A-118, Montreal, Quebec, Canada H3T 1E2 (Email: meisenberg{at}epid.jgh.mcgill.ca).
We appreciate the interest in our study (1) expressed by Dr. Chacko and Dr. Osman and colleagues. We agree that there is substantial evidence supporting the use of beta-blockers and angiotensin-converting enzyme (ACE) inhibitors among patients with coronary artery disease (CAD) and other co-morbid conditions. We also agree that a large proportion of post-coronary artery bypass graft (CABG) patients should therefore receive these agents including those with a history of myocardial infarction (MI), those with a low ejection fraction, and those with congestive heart failure. However, the routine use of these agents in all patients post-CABG is not currently supported by large randomized controlled trials (RCTs).
Few studies have examined the routine use of beta-blockers in post-CABG patients. In a single RCT, no significant differences were found in clinical end points including repeat revascularization, unstable angina, nonfatal MI, or death at two-year follow-up (2). Because many patients undergoing CABG are completely revascularized, the benefits of prescribing beta-blockers in patients without specific co-morbid conditions may be limited. Until large RCTs show a benefit with the routine use of beta-blockers in all post-CABG patients, we think that treatment should be limited to those patients with co-morbid conditions that are known to benefit from beta-blocker therapy.
Similarly, only one RCT, the QUO VADIS study, examined the routine use of ACE inhibitors in post-CABG patients (3). Although this trial suggested a significant decrease in ischemic events such as angina, death, MI, repeat revascularization, stroke, or transient ischemic attacks in patients treated with quinapril, only 149 patients were enrolled. Moreover, results from the PEACE trial suggest there may be a limited role for ACE inhibitors among patients with stable CAD and normal left ventricular function (4). Thus, until large RCTs demonstrate a benefit to the routine use of ACE inhibitors in all patients post-CABG, we believe their use should be limited to patients with co-morbid conditions known to benefit from ACE inhibitor treatment.
Thus, we agree that the current literature supports the use of beta-blockers and ACE inhibitors in various subgroups of CABG patients with cardiac co-morbidities. However, we are hesitant to recommend the routine use of these medications in all post-CABG patients when sufficient data from placebo-controlled trials do not exist. Larger RCTs, specifically conducted among CABG patients, are needed before we can recommend the routine use of beta-blockers and ACE inhibitors post-CABG.
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References
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1. Okrainec K, Platt R, Pilote L, Eisenberg MJ. Cardiac medical therapy in patients after undergoing coronary artery bypass graft surgery J Am Coll Cardiol 2005;45:177-184.[Abstract/Free Full Text]
2. MACB Study Group Effect of metoprolol on death and cardiac events during a 2-year period after coronary artery bypass grafting Eur Heart J 1995;16:1825-1832.[Abstract/Free Full Text]
3. Oosterga M, Voors AA, Pinto YM, et al. Effects of quinapril on clinical outcome after coronary artery bypass grafting (QUO VADIS study) Am J Cardiol 2001;87:542-546.[CrossRef][Web of Science][Medline]
4. Braunwald E, Domanski MJ, Fowler SE, et al. PEACE Trial Investigators Angiotensin-converting-enzyme inhibition in stable coronary artery disease N Engl J Med 2004;351:2058-2068.[Abstract/Free Full Text]
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