This study is a Phase III, randomized controlled, superiority trial, with two parallel groups, conducted in one academic medical center.  

The objective of this study is to assess the effectiveness of double sequence defibrillation in reverting patients with Atrial Fibrillation (AF) refractory to two trials of direct current cardioversion.

We hypothesize that in patients with AF refractory to 2 or more trials of Direct Current (DC) cardioversion, the use of double sequential defibrillation (DSED) has a higher success rate in terms of reverting patients to sinus rhythm as compared to an additional trial of DC cardioversion.

All AF patients admitted to the CCU for DC cardioversion, and refractory to at least two trials of DC cardioversion will be eligible for this study

Patients presenting to the CCU with persistent AFfor direct current (DC) cardioversion, who meet the inclusion criteria and fail to revert to normal sinus rhythm after two DC cardioversion attempts will be invited for enrollment in the study. No sampling will be carried out for the sake of this study.