CABG vs PCI for Left Main Coronary Stenosis
Abstract & Commentary
By Michael H. Crawford, MD Dr. Crawford is the Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco; and is the Editor of Clinical Cardiology Alert.
Source: Lee MS, et al. Comparison of Coronary Artery Bypass Surgery with Percutaneous Coronary Intervention with Drug-Eluting Stents for Unprotected Left Main Coronary Artery Disease. J Am Coll Cardiol. 2006;47:864-870.
Observations with new drug-eluting stents have suggested that percutaneous coronary intervention (PCI) on left main coronary artery stenosis unprotected by a bypass graft may be safe and effective. Therefore, Lee and colleagues at Cedars-Sinai Medical Center in Los Angeles report on the results of coronary artery bypass surgery (CABG) in 123 patients and PCI with drug-eluting stents in 50 patients treated after drug-eluting stents became available in 2003. The primary end point was freedom from major adverse cardiac and cerebrovascular events (MACCE) at 30 days and the end of follow-up (mean, 6 months). Comparison of the baseline characteristics of the 2 groups showed that the PCI group had fewer men, more chronic renal insufficiency, more patients with unstable angina, and more patients with a high surgical risk score (> 15 Parsonnet score). MACCE at 30 days for CABG was 17% and for PCI 2%, P < .01. The 6-month freedom from MACCE was 83% CABG and 89% PCI, P = .2. The results at 1 year were similar, and no component of the MACCEs was significantly different at 6 and 12 months of follow-up. In the 42% who had follow-up angiograms, freedom from target vessel revascularization at 6 months was 99% in the CABG group and 93% in the PCI group (P = .22). Multivariate analysis showed that the Parsonnet score, diabetes, and CABG were independent predictors of MACCE. Lee et al concluded that PCI for left main coronary artery stenosis is not associated with an increase in complications vs CABG for 6 months.
This is an interesting trial because it shows what can be accomplished using a multidisciplinary clinical judgment approach to a high-risk clinical situation. Left main coronary artery stenosis is a high-risk situation with a 20% 1-year mortality and a 50% 3-year mortality on medical therapy. The landmark VA study published in 1976 showed that CABG markedly reduced this mortality rate, and it has been the standard of care since. However, progress with PCI has suggested that it may be a competitive technique now and, perhaps, superior in selected patients. Thus, this experience with PCI for left main stenosis is timely.
Each patient was evaluated by an interventional cardiologist and a cardiac surgeon, and the best therapy was employed. Using this approach, less than one-third of the patients studied were allocated to PCI. Not surprisingly, those receiving PCI had significantly higher Parsonnet scores, as they were not ideal surgical candidates. So at the least the pre-procedure risk of both groups was comparable, yet there was a trend toward better outcomes with PCI, which diminished with time. A larger patient population may have shown statistical significance with some of the difference between PCI and CABG. On the other hand, a longer follow-up may have shown superiority of CABG. So, at this point PCI appears to be a viable alternative to CABG, especially when multidisciplinary clinical judgment is used to select treatment.
There are several limitations to this study. It is observational, so other biases may exist in patient selection beyond the baseline characteristics reported. There is no long-term follow-up. The sample size is small. Almost all the PCIs were done by one operator. The majority got Cypher stents. Biomarkers were not checked with either procedure. Finally, there was low compliance with follow-up angiograms. So, should a randomized, controlled trial be done? Perhaps, but it would only compare patients eligible for both procedures and eliminate clinical judgment. This may be a situation where careful observation of the results of clinical judgment may be sufficient to make sound recommendations. Clearly, more data are needed, but not necessarily a randomized trial.
It is worth pointing out that 64% of the PCI patients received intra-aortic balloon pumping prophylactically post procedure, but this may not turn out to be necessary. Also, only 14% of the PCI patients were treated with platelet glycoprotein IIb/IIIa agents because there is little experience with such agents in left main angioplasty; these patients are eliminated from most PCI trials. However, target vessel revascularization was low and exclusively seen in those with distal bifurcation lesions. CABG is probably best for these patients. Finally, Lee et al believe that in stent restenosis, post left main PCI should be treated with CABG.