Verapamil Therapy: A New Approach to Pharmacologic Treatment of Hypertrophic Cardiomyopathy

¹ From the Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD

The hemodynamic and clinical effects of verapamil administration were examined in patients with hypertrophic cardiomyopathy. Infusion of 0.021 mg/kg/mm of verapamil decreased the basal left ventricular outflow tract gradient from 94 ± 14 to 49 ± 14 mm Hg, while cardiac index increased from 2.5 ± 0.2 to 2.8 ± 0.2 L/min/sq m. Orally administered, 80 or 120 mg four times daily (QID), increased exercise capacity relative to placebo by 26 percent (1.6 ± 0.5 minute; p < 0.005) and propranolol, 40 or 80 mg QID, increased it by 21 ± 8 percent (1.3 ± 0.5 minute, p < 0.025). Nine patients considered their symptomatic status "best" while receiving verapamil, seven while receiving placebo, and only three while receiving propranolol. Seventy-three patients have been discharged from the hospital receiving longterm verapamil therapy, and 49 have reported continuing symptomatic benefit with many showing improved exercise capacity up to two years later. Thus, verapamil can improve exercise capacity and symptomatic status in certain patients with hypertrophic cardiomyopathy, thereby providing physicians with a new therapeutic agent for the treatment of this disorder.