BackgroundAtrial fibrillation is the most frequent sustained arrhythmia. Atrial fibrillation frequently recurs after restoration of normal sinus rhythm. Antiarrhythmic drugs have been widely used to prevent recurrence, but the effect of these drugs on all-cause mortality and other clinical outcomes is unclear. This is an update of a review previously published in 2007, 2012 and 2015. risk of mortality was higher in people taking quinidine, although the confidence interval also includes the possibility of no difference (RR 2.01, 95% CI 0.84 to 4.77; participants = 1646).No effect on mortality was apparent with the remaining drugs studied, but less data was available for them and it could be underpowered to detect small increases in mortality. In particular, very few data was available for flecainide (no death reported in any treatment arm in 4 RCTs studying flecainide, participants = 511) and propafenone (only 2 deaths reported in 5 included RCTs, participants = 998).