Abstract

Sudden strenuous exercise has been reported to cause ST-segment depression and a fall in left ventricular ejection fraction in healthy subjects who respond to maximal graded exercise without ST-segment depression and with increased ejection fractions. In order to assess the significance of this response for patients with coronary heart disease, we studied ten post-myocardial infarction (MI) patients who were receiving beta-blocking drugs. First-pass radionuclide angiocardiography and exercise electrocardiographic (ECG) studies were performed at rest (R1), 30 second of peak sudden strenuous exercise (SSE), rest (R2), and peak maximal graded exercise. Exercise was performed on an upright cycle ergometer. Heart rate-blood pressure products were comparable for both exercise protocols, and there was no significant difference in clinical or ECG indications of ischemia. Mean left ventricular ejection fraction was in the normal range at rest (R1) (52 +/-3) and did not change significantly with SSE (52 +/-3) or maximal graded exercise (52 +/-4). In contrast with what would have been expected from studies in healthy subjects, patients with MI who are receiving beta blockers do not have increased evidence of ischemia or left ventricular dysfunction during SSE as compared with maximal graded exercise. Verf.-Referat