A comparison of 50-J versus 100-J shocks for direct-current cardioversion of atrial flutter

Background Direct-current cardioversion remains the gold standard for resto ration of sinus rhythm in patients with atrial flutter. Although an initial energy of 50 J is recommended, the optimal energy settings have not been e valuated in a large series of contemporary patients. Methods We compared the outcome of cardioversion with 50 J versus 100 J in 330 consecutive patients with atrial flutter. Initial energy was based on a ttending physician preference. One hundred sixty patients received 50 J and 170 patients received 100 J. Results Patients in both groups did not differ significantly in age, sex, w eight, body mass index, duration of the arrhythmia, postoperative status, p resence and type of structural heart disease, or use of antiarrhythmic drug s. Patients in the 100-J group had more first shock conversion (85% vs 70%; P = .001), fewer total shocks (1.2 +/- 0.5 vs 1.4 +/- 0.7, P = .001), and less induction of atrial fibrillation (2% vs 11%; P = .002). There were no significant differences in overall restoration of sinus rhythm, cumulative energy delivered, anesthetic dose, and procedure room time. On multivariate analysis, delivery of 100 J was the strongest predictor of first shock suc cess (odds ratio 2.6, 95% confidence interval 2.13 to 3.16; P < .001). Conclusion An initial energy of 100 J is more efficient For restoration of sinus rhythm in patients with atrial flutter.