PCI versus CABG versus medical therapy in 2006

The decision to offer patients with myocardial ischemia a coronary artery bypass graft (CABG) surgery has been largely determined by extent of coronary artery disease (CAD) and left ventricular function, since the early 1970's. Based upon subset analyses, and long-term follow-up, of three moderate-sized trials of stable patients and two small trials of unstable angina (excluding recent myocardial infarction, MI) patients, the notion has persisted that patients with left main narrowing >50% or three-vessel stenoses >70%, or even two-vessel stenoses >70%, where one of the vessels is the proximal left anterior descending, derive a "survival benefit" relative to medical therapy (MED), from CABG (anatomic paradigm). The MED of the original CABG versus MED trials consisted of little more than anti-anginal medications, used on an as-needed basis. In the ensuing 3 decades, multiple large, well done, randomized clinical trials have established a survival benefit for 4 different forms of MED among a broad spectrum of CAD patients. Aspirin; lipid lowering, especially with statins; b-blockers; and angiotensin-converting-enzyme inhibitors and/or angiotensin receptor blocking agents; have all been shown to enhance survival, as well as reduce other objective adverse outcomes of CAD. The advances in MED, coupled with the small but significant mortality and morbidities of both CABG and percutaneous coronary intervention (PCI), are among the reasons to skeptically consider potential "survival benefit" of revascularization. A more common and far more easily justified reason to consider revascularization is to relieve "medically refractory" myocardial ischemia, particularly when the ischemia is accompanied by symptoms. Accordingly, documentation of medically refractory myocardial ischemia provides the answer to the first question of myocardial revascularization, "Is this patient likely to derive clinical benefit from revascularization, at this time?" It is only after this question has been answered that one needs to consider the relative advantages and disadvantages of PCI versus CABG (physiologic paradigm). Two of the relative advantages of PCI, namely speed of reperfusion, and relatively low morbidity, are among the reasons that most randomized trial data, and most clinical application of revascularization to patients with MI (ST-elevation MI [STEMI], and non-STEMI) have been by PCI. In contrast, for stable patients with medically refractory ischemia, anatomic considerations continue to be relevant to the choice between CABG and PCI. Specific advantages of CABG include: its potential to revascularize chronically occluded vessels with collaterals supplying viable myocardium; the fact that conduits protect territories rather than simply treating lesions; and the greater durability of conduits compared to bare-metal stents (drug-eluting stents may change the picture). Based on these principles, physiologic, rather than anatomic, considerations are most useful in determining whether to revascularize, and how urgently to revascularize (STEMI is an emergent indication and high-risk non-STEMI an urgent indication). Coronary anatomy, including both number of vessels and lesion characteristics, continues to help decide between CABG and PCI, and in formulating patient specific strategies.