Drug-Eluting Stents vs CABG for Multivessel Coronary Artery Disease
Abstract & Commentary
Andrew Boyle, MBBS, PhD Dr. Boyle is Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco. Dr. Boyle reports no financial relationships relevant to this field of study.
Source: Park D, et al. Long-term mortality after percutaneous coronary intervention with drug-eluting stent implantation versus coronary artery bypass surgery for the treatment of multivessel coronary artery disease. Circulation. 2008;117:2079-2086.
Coronary artery bypass graft surgery (CABG) has long been the standard of care for multivessel coronary artery disease. The introduction of drug-eluting stents (DES) resulted in a dramatic reduction in restenosis, leading to widespread adoption of this technology. Although multivessel stenting is an off-label use DES, anecdotal evidence has suggested excellent short-term outcomes, comparable to those achieved with CABG. Accordingly, Park and colleagues examined the long-term outcomes of DES vs CABG.
Park et al studied 3042 consecutive patients with multivessel coronary artery disease who underwent DES implantation (n = 1547) or CABG (n = 1495) at a single center. The decision to perform percutaneous coronary intervention (PCI) or bypass surgery was at the discretion of the physician and/or patient, and if PCI was performed, the type of DES was also at the physician's discretion. They excluded patients who presented with acute myocardial infarction within 24 hours, patients with cardiogenic shock, patients with previous CABG, and those who required concomitant valvular or aortic surgery. Baseline characteristics in the CABG group, compared to the DES group, showed more males and smokers and a higher prevalence of prior myocardial infarction, chronic lung disease, peripheral arterial disease, stroke, and renal failure. In addition, CABG patients had lower mean ejection fraction and higher likelihood of left main disease and 3-vessel disease. Patients receiving DES were more likely to have diabetes, hypertension, and prior PCI, as well as presented more often with unstable angina.
The mean number of stents used per case was 2.8 ± 1.2, with 79% being sirolimus-eluting stents and 21% being paclitaxel-eluting stents. The CABG group received arterial bypass grafts to the LAD in 96% of cases. The mean number of bypass grafts was 3.5 ± 1.1 (2.8 ± 1.1 arterial grafts and 0.7 ± 0.8 venous bypass grafts) per patient. Aspirin was prescribed indefinitely for all, and clopidogrel was prescribed for at least six months in DES patients, but the duration of clopidogrel therapy beyond this was at the physician's discretion. The mean duration of therapy was 12.1 ± 8.4 months. It is not stated whether the CABG patients received clopidogrel therapy or not.
The primary end point was all-cause mortality, and Park et al performed crude unadjusted analysis, as well as multivariable-adjusted analysis to allow for baseline differences between groups. Unadjusted in-hospital mortality was 1.5% for CABG and 0.6% for DES; P = 0.001. During the median follow-up of approximately 940 days, the unadjusted mortality for CABG was 7.0% and 4.4% for DES; P = 0.01. After multivariable adjustment, however, the mortality was similar in the two groups. In addition, Park et al calculated propensity scores and performed further analyses based on propensity scores, which also showed no difference in mortality. Importantly, adjusted mortality rates in diabetics and patients with impaired left ventricular function showed no difference between treatment groups.
The secondary end points were revascularization rates and the combined end point of death, Q-wave myocardial infarction, and stroke. Repeat revascularization was higher in the DES group, and was required in 11.8% of patients, compared to 4.6% of CABG patients; P < 0.001. The combined end point of Death, Q-wave MI, and stroke was not different between treatment groups. Stent thrombosis was defined by the academic research consortium definitions. Definite stent thrombosis occurred in 10 patients, probable in 2 patients, and possible in 22 patients. Importantly, of the 12 patients with definite or probable stent thrombosis, 25% were on dual anti-platelet therapy, 25% were on aspirin alone, and 50% were on no anti-platelet therapy at all. Furthermore, among the definite and probable stent thromboses, 1 occurred early, 3 late, and 8 occurred very late. Park et al concluded that PCI with DES results in equivalent long-term mortality as compared to CABG in patients with multivessel disease.
Commentary
This large observational study followed patients for approximately 3 years and demonstrated comparable mortality outcomes between PCI with DES implantation and the traditional treatment for multivessel disease, CABG. Park et al are to be commended on their rigorous statistical approach, presenting the data unadjusted, and then presenting the same data fully adjusted for multiple variables. Randomized, controlled trials are currently underway to compare multivessel PCI with DES to CABG, and the results of these trials are eagerly awaited. However, real-world data, such as the current study, allow important insights into the medium-term follow-up of these patients. The late-stent thrombosis rates were higher than the early-stent thrombosis rates, and it is compelling to note that half of these events occurred after cessation of all anti-platelet therapy. This underscores the need for prolonged dual anti-platelet therapy in all patients who undergo extensive coronary artery stenting. In addition, this should help inform future randomized trials comparing DES to CABG on optimal duration of clopidogrel therapy. This study was limited by 3-year follow-up; the longer-term outcomes of DES beyond this time-scale remain unknown. Many years of clinical experience with CABG informs us of the excellent long-term outcome of patients following this procedure. Park et al conclude that compared with CABG, PCI with DES showed comparable long-term mortality for the treatment of multivessel coronary artery disease, but was more likely to require repeat revascularization. Conclusions regarding a comparison of the two treatment strategies await the results of ongoing clinical trials.
Although multivessel stenting is an off-label use DES, anecdotal evidence has suggested excellent short-term outcomes, comparable to those achieved with CABG.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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