Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation
Abstract
Background
Atrial fibrillation (AF) is the most frequent sustained arrhythmia. AF recurs frequently after restoration of normal sinus rhythm. 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.
Search methods
We updated the searches of CENTRAL on The Cochrane Libary (Issue 1 of 4, 2010), MEDLINE (1950 to February 2010) and EMBASE (1966 to February 2010). The reference lists of retrieved articles, recent reviews and meta‐analyses were checked.
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. Studies were pooled, if appropriate, using Peto odds ratio (OR). All results were calculated at one year of follow‐up.
Main results
In this update, 11 new studies met inclusion criteria, making a total of 56 included studies, comprising 20,771 patients. Compared with controls, class IA drugs quinidine and disopyramide (OR 2.39, 95% confidence interval (95%CI) 1.03 to 5.59, number needed to harm (NNH) 109, 95%CI 34 to 4985) and sotalol (OR 2.47, 95%CI 1.2 to 5.05, NNH 166, 95%CI 61 to 1159) were associated with increased all‐cause mortality. Other antiarrhythmics did not seem to 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 0.70, number needed to treat (NNT) 3 to 16). Beta‐blockers (metoprolol) also reduced significantly AF recurrence (OR 0.62, 95% CI 0.44 to 0.88, NNT 9).
All analysed drugs increased withdrawals due to adverse affects and all but amiodarone, dronedarone and propafenone increased pro‐arrhythmia. We could not analyse other outcomes because few original studies reported them.
Authors' conclusions
Several class IA, IC and III drugs, as well as class II (beta‐blockers), are moderately effective in maintaining sinus rhythm after conversion of atrial fibrillation. However, they increase adverse events, including pro‐arrhythmia, and some of them (disopyramide, quinidine and sotalol) may increase mortality. Possible benefits on clinically relevant outcomes (stroke, embolisms, heart failure) remain to be established.
PICOs
Plain language summary
Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation
Atrial fibrillation is a disease where the heart rhythm is irregular (this is called arrhythmia) and too fast (this is called tachycardia, from the Greek "tachy" meaning fast). Atrial fibrillation may produce complications, either in the heart (heart failure, syncope) or in other organs (mainly causing embolisms, which is the formation of blood clots in the cavities of the heart that may then travel to other places, for example the brain).
Atrial fibrillation can be reverted, restoring normal heart rhythm, by using drugs or a controlled electrical shock. However, a major problem is that atrial fibrillation recurs frequently. A variety of drugs have been employed to avoid recurrences and keep normal heart rhythm. This systematic review looked at the effectiveness and safety of antiarrhythmic drugs used to prevent recurrences of atrial fibrillation.
We found 56 good quality studies testing various antiarrhythmic drugs, involving 20,771 patients. The cumulative data from these studies show that several drugs are effective at preventing recurrences of atrial fibrillation (quinidine, disopyramide, flecainide, propafenone, amiodarone, azimilide, dofetilide, dronedarone and sotalol), but all of them increased adverse effects. The data shows also that some of those drugs, one specific group called "class IA", which comprises quinidine and disopyramide, and sotalol, may cause a small increase in the number of deaths in treated patients. A limitation of the review was that the majority of the studies we found did not assess the complications most frequently seen with atrial fibrillation (embolisms and heart failure). Therefore, we can not know if treatment with antiarrhythmic drugs may have any effect reducing (or increasing) those complications.
It is unclear if the long‐term benefits obtained with antiarrhythmic drugs outweigh their risks.
