Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most frequent sustained arrhythmia. After restoration of normal sinus rhythm, the recurrence rate of AF is high. Antiarrhythmic drugs have been widely used to prevent recurrence, but the effect of these drugs on mortality and other clinical outcomes is unclear.
OBJECTIVES: To determine, in patients who recovered sinus rhythm after AF, the effect of long-term treatment with antiarrhythmic drugs on death, stroke and embolism, adverse effects, pro-arrhythmia and recurrence of AF. If several antiarrhythmics were effective our secondary aim was to compare them. SEARCH STRATEGY: The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Libary (Issue 2, 2005), MEDLINE (1950 to May 2005) and EMBASE (1966 to May 2005) were searched. The reference lists of retrieved articles, recent reviews and meta-analyses were checked. No language restrictions were applied. SELECTION CRITERIA: Two independent reviewers selected randomised controlled trials comparing any antiarrhythmic with a control (no treatment, placebo or drugs for rate control) or with another antiarrhythmic, in adults who had AF and in whom sinus rhythm was restored. Post-operative AF was excluded. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed quality and extracted data, on an intention-to-treat basis. Disagreements were resolved by discussion. Studies were pooled, if appropriate, using Peto odds ratio (OR). MAIN
RESULTS: 45 studies met inclusion criteria, comprising 12,559 patients. All results were calculated at 1 year of follow-up. Class IA drugs (disopyramide, quinidine) were associated with increased mortality compared with controls (OR 2.39, 95% confidence interval (CI) 1.03 to 5.59, P = 0.04, number needed to harm (NNH) 109, 95% CI 34 to 4985). Other antiarrhythmics did not modify mortality. Several class IA (disopyramide, quinidine), IC (flecainide, propafenone) and III (amiodarone, dofetilide, dronedarone, sotalol) drugs significantly reduced recurrence of AF (OR 0.19 to 0.60, number needed to treat 2 to 9), but all increased withdrawals due to adverse affects (NNH 17 to 36) and all but amiodarone and propafenone increased pro-arrhythmia (NNH 17 to 119). AUTHORS'
CONCLUSIONS: Several class IA, IC and III drugs are effective in maintaining sinus rhythm but increase adverse events, including pro-arrhythmia, and disopyramide and quinidine are associated with increased mortality. Any benefit on clinically relevant outcomes (embolisms, heart failure, mortality) remains to be established.