Patients with ischemic heart disease, congestive heart failure, and low ejection fraction are usually referred for orthotopic heart transplantation. Based on results of myocardial viability assessment, we have prospectively used either coronary artery bypass grafting or orthotopic heart transplantation. From January 1990 to June 1992, among 50 patients initially referred for heart transplantation, 46 showing myocardial viability underwent bypass grafting. Forty-five of these 46 patients were men, and the mean age was 58 +/- 12 years (range, 40 to 70 years). Congestive heart failure was present in all patients, and dyspnea was the main symptom in 80% (37/46). Patients were selected according to three criteria. (1) Myocardial viability was primarily assessed by thallium scintigraphy for up to 24 hours (28/46 patients). When results were negative, patients underwent positron emission tomography (20/46 patients). (2) Regional left ventricular function was assessed using gated blood pool single-photon emission computed tomography combined with (3) full hemodynamic evaluation. Results were as follows: end-diastolic volume, 129 +/- 35 mL/m2; ejection fraction, 0.23 +/- 0.06; cardiac index, 2.4 +/- 0.62 L.min-1.m-2; mean pulmonary artery pressure, 26 +/- 0.90 mm Hg; and mean pulmonary capillary wedge pressure, 16 +/- 1.10 mm Hg. Operative mortality was 2.17% (1/46). During follow-up (mean duration, 18 months), there were three late cardiac-related deaths (arrhythmias) and two noncardiac-related deaths. The 40 long-term survivors are in New York Heart Association class II. Angiography (15 patients) or gated blood pool single photon emission tomography (32) showed improvement in mean ejection fraction to 0.39 +/- 0.13 (range, 0.22 to 0.46).(ABSTRACT TRUNCATED AT 250 WORDS)