Suppressing sympathetic activation with clonidine on ventricular arrhythmias in congestive heart failure.

This randomized, double-blind, placebo-controlled study examines the effects of clonidine (a centrally acting sympathoinhibitor) on ventricular arrhythmias in 35 patients with congestive heart failure (CHF) by using the 24-h ambulatory electrocardiographic recording. After baseline examination and Holter recording, patients were balanced and 18 patients were randomized to clonidine group and 17 patients to placebo group. After four weeks of clonidine (given as a transdermal patch) or matching placebo therapy, a second Holter recording was obtained. The placebo group showed no change in the frequency of ventricular arrhythmias whereas the clonidine-treated group showed a significant decrease in the frequency of ventricular premature beats by 68% (P<0.01), couplets by 63% (P<0.01) and episodes of non-sustained ventricular tachycardia by 60% (P<0.05). Clonidine also decreased heart rate and arterial blood pressure, but left ventricular ejection fraction was slightly improved. It is concluded that sympathetic suppression with clonidine reduces the frequency of ventricular arrhythmias in patients with CHF, which suggests that sympathetic activation plays a role in arrhythmogenesis in these patients.