Efficacy of propranolol in the control of exercise-induced or augmented ventricular ectopic activity.

The effect of propranolol on exercise-induced or augmented ventricular ectopy was studied in sixteen male patients, six of whom had documented coronary artery disease. Fifteen patients were exercised after two weeks of oral therapy, fourteen after single oral therapy and eight patients after intravenous therapy. Propranolol dosage was titrated to produce maximal beta-adrenergic blockade. Effective reduction of exercise-induced ventricular ectopy occurred in ten of fifteen patients (P less than 0.001), and in five of six patients with coronary disease (P less than 0.02). Propranolol therapy abolished ventricular couplets in eight of twelve patients and ventricular tachycardia in four of the patients. Single oral and intravenous therapy had similar or greater effects. Plasma propranolol levels following different routes of administration did not correlate with exercise-induced maximal heart rates or percent reduction in ventricular ectopy. When compared to exercise in eleven patients, ambulatory monitoring underestimated the severity, particularly the highest grades, of ventricular ectopy.