Background: The best primary revascularization strategy for isolated lesions of the left anterior descending coronary artery remains controversial. Aziz and colleagues conducted a meta-analysis to compare results from studies of the two leading strategies, percutaneous transluminal coronary artery stenting and minimally invasive direct coronary artery bypass with the left internal thoracic artery.
The Study: The authors searched electronic databases to identify all relevant studies published between 1966 and 2006. Data were extracted from each study regarding the outcomes of anginal recurrence, myocardial infarction (MI) within 30 days of procedure, MI during follow-up, stroke, mortality from any cause, revascularization procedure, and any other major adverse cerebral or coronary event.
Results: The 12 studies identified included 1,952 patients, of whom 67 percent were treated with transluminal stenting. The four studies reporting recurrence of angina showed a significantly higher rate after transluminal stenting than thoracic artery bypass (29 versus 14 percent; odds ratio [OR] = 2.62). The number needed to treat (NNT) to avoid one case of anginal recurrence was 7. Percutaneous stenting was also associated with significantly higher rates of major adverse coronary and cerebral events than was thoracic artery bypass in the three studies reporting this outcome (30 versus 11 percent; OR = 2.86; NNT = 5); and with significantly higher rates of repeat revascularization in the six trials reporting this outcome (13 versus 4 percent; OR = 4.63; NNT = 11).
Conversely, no significant difference could be demonstrated between the two treatment strategies for postoperative MI, stroke, or mortality. In the five randomized controlled trials included in the meta-analysis, the incidence of postoperative MI was 3.7 percent after transluminal stenting compared with 2.7 percent after bypass surgery. When data from all studies that reported postoperative MI were pooled, the rates were 1.3 percent for transluminal stenting and 1.7 percent for bypass. No significant difference could be demonstrated between the strategies in the five studies that reported on postoperative stroke or transient ischemic attack (1.9 percent for stenting versus 0.5 percent for bypass). At maximal follow-up, there was no significant difference in mortality (1.7 percent for stenting compared with 3.4 percent for bypass).
Conclusion: The authors conclude that minimally invasive direct coronary artery bypass provides superior revascularization compared with percutaneous transluminal stenting for isolated lesions of the left anterior descending coronary artery. Bypass is also associated with a lower incidence of some serious adverse effects, including angina, need for revascularization, and major coronary or cerebrovascular events. The authors acknowledge that their results cover relatively short follow-up periods and, as composites of several published studies, could be subject to selection and publication bias. Nevertheless, they conclude that minimally invasive surgery may show even greater relative benefit as surgical techniques, including robotic surgery, continue to advance.
editor's note: Two related articles and an editorial address the wider implications and economic aspects of this and related studies concerning coronary revascularization.1–3 Overall, studies indicate better survival after bypass surgery than after stenting, and the advantage may be even greater in patients with diabetes. The advantage of surgery may be attributable to coverage of larger areas of diseased blood vessels and protection against development of new disease, as well as to the risk of late thrombosis and endothelial damage by stents. The economic analyses conclude that bypass grafting is cost-effective but that stenting is not.
Further complicating the debate is recent research on the effectiveness of medical therapy. One estimate is that medical therapy and bypass surgery are cost-effective (based on a quality-adjusted life-year cost of $58,000), but that stents are not. In many centers, stents appear to have become standard therapy without careful comparative studies that demonstrate benefit. With the current scientific literature showing clear trends to better results at lower costs from bypass or medical therapy, the influence of the $6-billion-per-year “stent industry” is being questioned.3—a.d.w.