Persisting Effect of Ca2+-Channel Blockers on Left Ventricular Function in Hypertrophic Cardiomyopathy After 14 Years' Treatment

Abstract

Ca²⁺-channel blockers of the verapamil type have been reported to exert a beneficial effect on clinical symptoms and survival rates in hypertrophic cardiomyopathy. The effects of verapamil have been attributed predominantly to an improved diastolic filling. It is unknown whether an effect on diastolic filling persists in these patients after long-term treatment. Fourteen patients (12 men, 2 women, median age fifty-one [thirty-two to fifty-five] years) with hypertrophic cardiomyopathy were included in the study. Patients had been treated with verapamil 240-480 mg/d or gallopamil 150-200 mg/d for fourteen (seven to seventeen) years. The effect of a withdrawal of Ca²⁺-channel blockers on parameters of left ventricular diastolic function was evaluated at rest and during exercise in patients with hypertrophic cardiomyopathy after long-term therapy. Investigations were performed at rest and during supine ergo metric exercise during ongoing Ca²⁺-channel blocking therapy and after five (four to nine) days' withdrawal (control). Pulsed Doppler echocardiography was used to record diastolic mitral flow profiles from an apical four-chamber view.

Withdrawal of Ca²⁺-channel blockers of the phenylalkylamine type after long-term treatment of hypertrophic cardiomyopathy resulted in a significant reduction of early diastolic inflow velocity at rest and during exercise. In conclusion, these results indicate a persistent improvement of early diastolic filling by Ca²⁺-channel blockers even after long-term treatment.