Verapamil therapy: a new approach to pharmacologic treatment of hypertrophic cardiomyopathy.

The hemodynamic and clinical effects of verapamil administration were examined in patients with hypertrophic cardiomyopathy. Infusion of 0.021 mg/kg/min 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% (1.6 +/- 0.5 minute; p less than 0.005) and propranolol, 40 or 80 mg QID, increased it by 21 +/- 8% (1.3 +/- 0.5 minute, p less than 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 long-term 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.