Relation of baseline characteristics to suppression of ventricular arrhythmias during placebo and active antiarrhythmic therapy in patients after myocardial infarction

Sotalol

Sotalol is a novel antiarrhythmic agent combining beta-adrenergic-antagonist actions with the ability to increase cardiac repolarization and refractoriness. The drug's electrophysiologic and clinical profile is different from that of conventional beta-receptor antagonists. As compared with other antiarrhythmic agents, sotalol prevents recurrences of arrhythmia in a higher proportion of patients, particularly among those presenting with ventricular tachycardia and aborted sudden cardiac death. The net hemodynamic effect of sotalol is the result of a balance between the depressant effects due to beta-receptor blockade and an action that tends to increase contractility. Although initially marketed in the United States for treatment of life-threatening ventricular arrhythmias, sotalol also has demonstrated efficacy in many patients with supraventricular arrhythmias. As with all drugs that prolong the QT interval, the syndrome of torsade de pointes is a serious potential adverse effect.

Sotalol. An updated review of its pharmacological properties and therapeutic use in cardiac arrhythmias

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.

Effects of advancing age on the efficacy and side effects of antiarrhythmic drugs in post-myocardial infarction patients with ventricular arrhythmias. The CAST Investigators

OBJECTIVE

To determine the effect of age on the response to anti-arrhythmic drugs.

DESIGN

Randomized controlled trial comparing particular drugs.

SETTING

Multi-institutional (The Cardiac Arrhythmia Suppression Trial, CAST).

PARTICIPANTS

2,371 patients, age less than 80, with ventricular arrhythmias after a recent myocardial infarction. Subjects classified by age as less than or equal to 55, 56-65, and 66-79 years.

INTERVENTION

Upwardly titrated doses of encainide, flecainide or moricizine. After identification of a tolerated and effective dose of one of the drugs, participants were randomized to that drug and dose versus its placebo for up to 10 months.

MAIN OUTCOME MEASURES

Efficacy of drug (suppression of ventricular premature depolarizations and/or non-sustained ventricular tachycardia), side effects and mortality.

RESULTS

Older patients had more previous MIs, congestive heart failure (CHF), hypertension, NSVT, repolarization abnormalities, digitalis use, and diuretic use. They had less pathologic Q-waves or electrocardiographic injury pattern, and their left ventricular ejection fraction (LVEF) was lower. First dose VPD suppression with the first drug averaged 53% and is not associated with age (P = 0.29). Adverse events including death are more frequent in older patients taking study drugs (P less than 0.001). This trend is consistent in all three study drugs and at varying LVEFs. History of prior MI, low LVEF, VPD (in log scale), and digitalis therapy also correlates with adverse events (all P less than 0.05). Following adjustment for these factors, older age is an independent predictor of adverse events (relative risk 1.30 per decade of age, P less than 0.001).

CONCLUSIONS

Older age increases the susceptibility to adverse cardiac events from a class of relatively toxic antiarrhythmic agents.

Short- and long-term antiarrhythmic and hemodynamic effects of d,l-sotalol in patients with symptomatic ventricular arrhythmias

The antiarrhythmic and hemodynamic effects of sotalol (160 to 480 mg/day), a beta-blocking agent that prolongs ventricular repolarization, were examined in 38 patients with complex symptomatic ventricular ectopic activity. During ambulatory monitoring, 24 patients (63%) exhibited a reduction of greater than 75% in single ventricular premature beats (VPBs) and greater than 90% reduction in repetitive arrhythmia. In contrast to the effects of other agents, left ventricular ejection fraction as determined by radionuclide angiography was not impaired, increasing slightly from 45 +/- 14% to 47 +/- 14% during therapy (p less than 0.05). Antiarrhythmic drug efficacy did not correlate with baseline ejection fraction or sotalol-induced changes in ventricular function. Late follow-up studies disclosed that antiarrhythmic efficacy and tolerance were maintained in the majority of patients. Repeat radionuclide angiography at 6 months revealed no late drug-induced depression of left ventricular function. Sotalol appears to be an effective and well tolerated agent for treatment of complex ventricular ectopic activity, even in the setting of compromised cardiac function.