The results of prosthetic valve replacement in 64 patients and coronary revascularization or aneurysmectomy in 58 patients were analyzed 1 year after the operation. 24 early and late deaths were found to be associated with a technical complication of surgery, new myocardial infarction, or in some instances persistent, unexplained heart failure. Left ventricular ejection fraction was lower at pre-operative cardiac catheterization among those patients who died with persistent, unexplained heart failure after surgery than among the other patients who underwent operation. A low left ventricular ejection fraction indicates a depressed state of myocardial contraction which may prove unresponsive to corrective valvular surgery or revascularization. Thus ideally surgery should be performed prior to the development of depressed myocardial contraction.