Sotalol is a nonselective
beta-adrenoceptor antagonist which prolongs cardiac repolarisation independently of its antiadrenergic action (class III antiarrhythmic properties). The antiarrhythmic action of
sotalol appears to arise predominantly from its class III properties, and the
drug exhibits a broader antiarrhythmic profile than the conventional beta-blockers.
Sotalol is effective in controlling
paroxysmal supraventricular tachycardias and the ventricular response to
atrial fibrillation/flutter in
Wolff-Parkinson-White syndrome, in maintaining sinus rhythm after
cardioversion of
atrial fibrillation/flutter, and in preventing initiation of supraventricular
tachyarrhythmias following
coronary artery bypass surgery.
Sotalol shows promise in the control of nonmalignant and life-threatening ventricular arrhythmias, particularly those associated with ischaemic
heart disease. It is effective in suppressing complex forms of ventricular ectopy, displaying superior antiectopic activity to
propranolol and
metoprolol. The acute efficacy of
sotalol in preventing reinduction of sustained
ventricular tachyarrhythmias and suppressing spontaneous episodes of these arrhythmias on Holter monitoring is translated into long term prophylactic efficacy against
arrhythmia recurrence in approximately 55 to 85% of patients with refractory life-threatening ventricular arrhythmias. In addition,
sotalol offers the advantage over the class I agents of reducing cardiac and all-cause mortality in the high risk population with life-threatening ventricular arrhythmias. The adverse effects of
sotalol are primarily related to its beta-blocking activity and its class III property of prolonging cardiac repolarisation.
Sotalol is devoid of overt cardiodepressant activity in patients with mild or moderate
left ventricular dysfunction. The overall arrhythmogenic potential is moderately low, but
torsade de pointes may develop in conjunction with excessive prolongation of the QT interval due to
bradycardia, hypokalaemia or high plasma concentrations of the
drug. In summary,
sotalol displays a broad spectrum of antiarrhythmic activity, is haemodynamically well tolerated, and confers a relatively low proarrhythmic risk. It is likely to prove particularly appropriate in the treatment and prophylaxis of life-threatening
ventricular tachyarrhythmias.