This study investigated whether the measurement of plasma free fatty acids (FFAs) could assist in the early detection of exercise-induced myocardial ischemia. Fifteen subjects with effort angina pectoris underwent angina-limited supine bicycle ergometer exercise testing. Myocardial FFA extraction decreased significantly from 22.8 +/- 3.1% at rest to 7.7 +/- 1.5% at peak exercise (p less than 0.05). Myocardial lactate extraction showed no significant change between rest and peak exercise. After control exercise testing, 8 subjects were given a single oral dose of nilvadipine (6 mg) and then again underwent exercise testing for the same duration. Nilvadipine lessened or abolished chest pain and there was less depression of the ST segment at peak exercise. Furthermore, myocardial FFA extraction showed no significant change between rest and peak exercise after nilvadipine administration. These results suggest that myocardial FFA extraction can be used to assess the presence of exercise-induced myocardial ischemia at an earlier stage than myocardial lactate extraction.