Revascularization therapy for coronary artery disease. Coronary artery bypass grafting versus percutaneous transluminal coronary angioplasty.

Coronary artery bypass surgery relieves the symptoms of myocardial ischemia and prolongs survival of patients with more severe coronary artery disease. Randomized trials of surgical therapy have consistently shown that the benefits of surgical revascularization are proportional to the amount of myocardium affected by, or at risk for, ischemic injury. This risk is inferred from angiographically delineated coronary anatomy, estimates of left ventricular function, and physiologic testing. The population that may see a survival benefit from surgical revascularization has probably been expanded beyond that reported in the VA, CASS, and ECSS trials, due to improved perioperative care, longer graft survival, and the use of internal mammary artery grafts. Percutaneous transluminal coronary angioplasty revascularizes myocardium by dilating a stenotic segment of coronary artery. While successful in relieving the symptoms of myocardial ischemia, PTCA is hindered by the occurrence of abrupt vessel closure and the frequent development of restenosis. Furthermore, firm proof of a survival benefit, outside of emergency therapy for acute myocardial infarction, is not yet available. However, because the risk of procedure-related death or serious complication is lower than that seen with bypass surgery, PTCA provides a useful alternative revascularization method for patients with less extensive disease, in whom the risk of surgery may equal or exceed any beneficial effect. New technology and growing experience are widening the scope of percutaneous revascularization by extending the hope of symptomatic relief and survival benefit even to patients with extensive, severe coronary artery disease. Comparisons between surgical therapy and PTCA in select populations with single- and multivessel coronary artery disease have shown that PTCA is not as effective as surgery for long-term symptomatic control, and that it often requires repeat PTCA or cross-over to bypass surgery; however, long-term outcomes (i.e., death and myocardial infarction) are similar. The cost of treatment beginning with PTCA may be lower than that of initial surgery, even when the increased need for repeat revascularization is taken into account. Despite this, surgical bypass remains the mainstay of therapy for patients with severe coronary artery disease and a poor prognosis for survival, and will remain the fallback procedure for patients who repeatedly undergo failed PTCA. At the present time, revascularization should be offered on the basis of symptom severity (in the presence of medical therapy) and in accordance with the prognosis for survival as judged by the extent and severity of disease (Table VI). Percutaneous transluminal coronary angioplasty is preferred in patients who require revascularization but can obtain no proven benefit from bypass surgery. Coronary artery bypass surgery, using the internal mammary artery when possible, remains the revascularization method of choice for patients with more severe disease or whose disease is not amenable to treatment using percutaneous methods (Table VII).