Left main coronary artery stenosis: the influence of aortocoronary bypass surgery on survival.

A retrospective study was carried out in 114 unoperated and 197 operated patients having left main coronary artery (LMCA) stenosis greater than or equal to 50%. Including the operative mortality of 9.1%, survival at seven years was significantly greater following pure aortocoronary bypass graft surgery, 77.5% as compared to 48.5% for the unoperated patients (P less than 0.01). The surgical mortality was significantly less during the last five years (1972-1976), 6.2% as compared to 17% during 1969-1971 (P less than 0.025). The three year survival in patients operated since 1972 was 90.2% as compared to 60.4% for unoperated patients. Survival remained significantly higher in the operated patients when studied as subsets on the basis of the severity of the LMCA stenosis (less than 70% as opposed to greater than or equal to 70%), and on the extent of associated obstructive disease of major coronary arteries (0-1 versus 2-3 arteries). It was significantly higher, however, only in operated patients with associated stenosis greater than or equal to 70% of the right coronary artery. Survival was higher following surgery only when the ejection fraction was at least 0.45, or the left ventricular end-diastolic pressure below 20 mm Hg.