In 12 patients with silent myocardial ischemia (fall of the ejection fraction (EF) greater than or equal to 5%, without angina pectoris) and in 15 symptomatic patients with coronary heart disease (fall of the EF during exercise EF greater than or equal to 5%, with angina pectoris), the left ventricular ejection fraction and the diastolic function (Peak Filling Rate, PFR; Time to Peak Filling Rate, TPFR) were evaluated before coronary artery bypass surgery and afterwards by the aid of the Nuclear Stethoscope. Our results showed a slight insignificant improvement in the EF from 60 +/- 8.3 per cent at rest to 66 +/- 7.9 per cent vs. 57 +/- 12 per cent to 62.6 +/- 9 per cent in patients with silent ischemia and in patients with angina pectoris after surgery. In contrast to this the EF increased significantly during exercise both in patients with silent ischemia from 52.0 +/- 15.2 per cent to 70.1 +/- 7.9 per cent and in symptomatic patients after revascularisation from, 49 +/- 11.7 per cent on to 64.2 +/- 8.4 per cent (both p less than 0.0001). There was also a similar significant improvement in the diastolic function, whereby the PFR was enhanced from 2.52 +/- 0.54 EDV/sec to 3.31 +/- 0.87 EDV/sec (p less than 0.02) in patients with silent myocardial ischemia and from 2.55 +/- 0.86 EDV/sec to 3.40 +/- 0.98 EDV/sec (p less than 0.02) in symptomatic patients. The TPFR showed a similar improvement.