Effect of oral captopril on premature ventricular complexes in patients with preserved left ventricular systolic function: a randomized clinical trial

Effect of beta-blocker therapy on severe ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy

Beta-blocker therapy has been shown to improve cardiac function and prognosis in patients with idiopathic dilated cardiomyopathy (DCM). However, whether beta-blockers reduce severe ventricular arrhythmias and sudden cardiac death has not been clarified. The present study was designed to investigate the effects of beta-blockers on non-sustained ventricular tachycardia (VT) and sudden cardiac death in patients with DCM. Sixty-five patients with DCM treated with diuretics, digitalis and angiotensin-converting enzyme inhibitors were assigned to receive beta-blockers (n = 33) or not (n = 32). Mean follow-up was 53+/-30 months. The echocardiographic indices of cardiac function, the incidence of non-sustained VT on Holter monitoring electrocardiograms, and sudden cardiac death rate were compared between the 2 groups. Comparable improvement in cardiac function on echocardiograms was found in the 2 treatment groups. The patient group treated with beta-blockers showed a significant reduction in the prevalence of VT (from 43 to 15%, p<0.05) and the development of new episodes of VT (5 vs. 16%) compared to the group without beta-blockers. The sudden cardiac death rate did not differ between the 2 groups. The results of the present study suggest that beta-blockers are effective in reducing severe ventricular arrhythmias in patients with DCM.

Effect of captopril on membrane currents of ventricular myocytes

Using whole-cell patch-clamp technique, the present study examined the effects of captopril on membrane currents of ventricular myocytes. The results were as follow: when the concentration of captopril was 6 x 10(-4)mol, the fast inward sodium current and slow inward calcium current were all decreased significantly (P < 0.05). Besides, when the concentration exceeds 10(-3)mol, the delayed rectifier potassium current was increased (P < 0.05) as well. But if the experimental concentration was under 6 x 10(-4)mol, these three kinds of currents was not affected. These findings suggested that captopril has no direct antiarrhythmic effect at the average therapeutic serum level.