Effect of oral propranolol on left ventricular performance in patients with ischemic heart disease. Ear densitographic study during uninterrupted treadmill exercise.
The effect of oral propranolol on left ventricular performance during early upright exercise was evaluated by ear densitography in patients with arteriographic coronary artery disease (CAD). Measurements of systolic time intervals differentiated 10 unmedicated patients with CAD (group 1) and 15 patients with CAD taking propranolol (group 3). The patients in group 3 had less shortening of preejection period at 1 minute and 4 minutes of exercise than group 1 patients (p less than 0.001 and p less than 0.005, respectively), with propranolol appearing to prevent the abnormal shortening of preejection period seen in the unmedicated group. Group 3 patients, in contrast to group 1 patients, showed reduction of heart rate and heart rate-blood pressure product both at rest and during exercise. Furthermore, PEP/LVET and percentage change in PEP/LVET from control responses were similar to those of subjects free of CAD (group 2). These results indicate that propranolol effects a favorable change in LV performance by postponing early exhaustion of cardiac reserve, despite significant CAD. There was relatively large overlap in percentage change in PEP/LVET from control between group 2 and group 3 in contrast to the clear separation among unmedicated patients. Thus, the excellent diagnostic accuracy of systolic time intervals recorded during exercise is greatly reduced by beta-adrenoceptor blockade.