PCI vs. CABG in High-Risk Patients
March 1, 2002
PCI vs. CABG in High-Risk Patients
Abstracts & Commentary
Synopsis: PCI and CABG were both acceptable revascularization strategies for high-risk patients with medically refractory angina.
Sources: Morrison DA, et al. J Am Coll Cardiol. 2002;39:266-273; Morrison DA, et al. J Am Coll Cardiol. 2001;38:143-149.
The angina with extremely serious operative Mortality Evaluation (AWESOME) Trial was designed to evaluate the outcomes of patients with medically refractory ischemia and risk factors for adverse outcomes with coronary artery bypass graft (CABG) surgery when randomized to a revascularization strategy of percutaneous coronary intervention (PCI) vs. CABG. High-risk inclusion criteria included age > 70 years, prior CABG, left ventricular ejection fraction (LVEF) < 0.35, myocardial infarction (MI) within 7 days, and medical instability requiring intra-aortic balloon pump (IABP) support. Hence, this study evaluated a patient population underrepresented, if not excluded, from previously published clinical trials comparing PCI vs. surgical revascularization. The primary end point of the randomized trial was survival at 3 years.
The results from the randomized portion of AWESOME were published in July 2001. For this VA Cooperative Study, 22,662 patients were screened at 16 VA Medical Centers. In this trial, 2431 patients were clinically eligible (medically refractory, with at least 1 high-risk characteristic), and 781 were felt to be angiographically acceptable, meaning that a participating interventionalist and surgeon agreed that the patient was an appropriate candidate for revascularization by either PCI or CABG. Of these, 454 patients consented to participate in the randomized portion of the trial. Additionally, 232 were randomized to CABG and 222 were randomized to PCI. In the randomized trial, there were no significant differences in survival between the CABG and PCI groups at 30 days (95% vs 97%), 6 months (90% vs 94%), or 36 months (79% vs 80%) of follow-up. As in previous randomized trials comparing the 2 strategies for revascularization, patients randomized to PCI had higher rates of repeat revascularization in the follow-up period. Survival free from unstable angina or repeat revascularization was significantly higher in the CABG group compared with the PCI group (62% vs 48%; P = 0.001). Morrison and colleagues concluded that PCI is an acceptable alternative to CABG for high-risk patients with medically refractory angina.
More recently, data derived from AWESOME registries were published. The AWESOME registries included 1977 patients who were clinically eligible, but not randomized into the trial. Of these, 1650 patients had treatment guided by physician preference and the remaining 327 had treatment guided by patient preference. The physician-directed registry included those patients that were not deemed appropriate candidates for either revascularization strategy and, therefore, could not be entered into the randomized trial. Hence, the physician-directed registry contained higher percentages of patients with significant left main coronary artery disease, prior CABG, saphenous vein graft disease and New York Heart Association (NYHA) Class III/IV heart failure. Within the physician-directed registry, 651 patients received PCI and 692 underwent CABG. Patients with 3-vessel disease, left main disease, proximal LAD disease, or NYHA Class II/IV heart failure were more likely to be referred for CABG. Patients with a history of MI, CABG, or PCI were more likely to be directed by their physician toward PCI. Patients in the patient-choice registry tended to choose PCI (n = 207) rather than CABG (n = 127). The patient-choice registry represented a lower risk subgroup than either the physician-directed registry or the randomized trial.
There were no differences in survival among the randomized patients, the physician-directed registry patients, or the patient-choice registry patients, regardless of the revascularization strategy chosen. Survival free from angina was slightly lower for patients undergoing PCI than for patients undergoing CABG in the physician directed registry only, and then only at the 6-month time point. In conclusion, Morrison et al felt the results from both registries were consistent with the results of the randomized trial, that PCI and CABG were both acceptable revascularization strategies for high-risk patients with medically refractory angina.
Comment by Sarah M. Vernon, MD
The conclusions of AWESOME are similar to the conclusions of many randomized, clinical trials comparing surgical and percutaneous revascularization that came before it. As in previously published trials, CABG and PCI both seemed to be acceptable modes of revascularization with equivalent survival rates, with the proviso that patients receiving PCI-based revascularization are more likely to require repeat revascularization in follow-up. As in previously published trials, the patients randomized in AWESOME are a highly selected group (22,662 patients were screened over 5 years at 16 institutions to randomize only 454), but this trial differs in that it specifically sought to include those high-risk patients that would have been excluded from most previous clinical trials. In addition to inclusion of high-risk patients, AWESOME is also notable for its "processes of care." Medical therapy was truly intensive, and was optimized according to specific physiologic guidelines such as heart rate and blood pressure. Hence, rates of ASA, heparin, and beta-blocker use were higher than in previous trials and consequently, ischemia was more clearly refractory in patients who were entered into this study. As in any clinical trial, the revascularization techniques used in AWESOME, both surgical and percutaneous, evolved over the 5 years of randomization. The use of arterial conduits, coronary stents and glycoprotein IIb-IIIa inhibitors, particularly in the latter part of the study, are in keeping with rates used in contemporary revascularization procedures, making these results more clinically relevant than those from studies evaluating balloon angioplasty for percutaneous revascularization, for example. The study is limited by its smaller-than-hoped-for sample size, its highly selected patient population, its rather heterogeneous inclusion criteria of "high-risk," and by its paucity of female patients. Despite these limitations, the combination of the randomized trial and the registries from AWESOME suggest that even in high-risk patients and medically refractory patients, both PCI and CABG are acceptable strategies for revascularization.
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