Thus, two quite effective interventions are available for patients with symptomatic coronary artery disease sufficient to require palliation by some mechanical means. Each has strengths and weaknesses. PTCA is relatively noninvasive, requires initially fewer hospital days and less intensive care, and preserves veins and mediastinum for CABG should it be required later. However, not all lesions present in a patient with multivessel disease can be dilated. There is substantial risk of restenosis and recurrence of symptoms, and a small but finite risk of having to undergo immediate CABG surgery following a failed PTCA, considerably increasing the risk of the surgery. CABG surgery results in more complete revascularization and relatively low short-term graft closure, and it can be done with an acute risk approximately equal to PTCA. However, it is apparent that surgical intervention does not change a patient's propensity to atherosclerosis; in ten years two-thirds of grafts have been compromised with atherosclerosis or thrombosis and there has been progression of atherosclerosis in the native, non-bypassed coronary circulation in roughly one-half of the patients. Second operations are considerably more difficult technically, carry a higher operative risk, and result in less dramatic relief of symptoms. There is a substantial population of patients with severe, symptomatic, multivessel coronary disease in whom it is unclear whether PTCA or CABG should be applied first.