Efficacy of carvedilol on complex ventricular arrhythmias in dilated cardiomyopathy: double-blind, randomized, placebo-controlled study.

AIMS The aim of the present study was to investigate whether the addition of carvedilol to conventional therapy in dilated cardiomyopathy patients is associated with further benefits in the treatment of complex non-sustained ventricular arrhythmias (Lown class III, IV or V). METHODS AND RESULTS We recruited 168 patients with ischaemic or idiopathic dilated cardiomyopathy, with complex ventricular arrhythmias. Patients able to tolerate low doses of carvedilol were randomized to treatment with carvedilol or placebo for 6 months. Carvedilol treatment improved ventricular function and reduced the incidence of arrhythmic episodes. Notably, by the end of the first month of treatment, the antiarrhythmic efficacy of the drug was significantly greater in patients with ischaemic than in those with idiopathic dilated cardiomyopathy, an effect that could probably be attributed to the anti-ischaemic properties of carvedilol. After 3 months, at a time when ejection fraction was significantly improved in all treated patients, the antiarrhythmic efficacy of carvedilol was similar in the two study groups. CONCLUSIONS Carvedilol antiarrhythmic efficacy was paralleled by the improvement in ejection fraction, independent of the aetiology of heart failure. The possibility of adding to an already 'optimized' conventional therapy a drug able to reduce the incidence of complex non-sustained ventricular arrhythmias is a therapeutic option that should be considered in the treatment of these patients.