Disappointing success of electrical cardioversion for new-onset atrial fibrillation in cardiosurgical ICU patients

OBJECTIVES To assess the success of electrical cardioversion for the treatment of new-onset atrial fibrillation in critically ill patients and to evaluate the stability of sinus rhythm in responders during the subsequent 24 hours. DESIGN Retrospective study. SETTING Twelve-bed cardiosurgical ICU at a university hospital. PATIENTS Seventy-two consecutive patients with postoperative new-onset atrial fibrillation (<7 d of duration) treated by electrical cardioversion. INTERVENTIONS Electrical cardioversion using synchronized biphasic shocks. MEASUREMENTS AND MAIN RESULTS During 144 electrical cardioversions, 209 shocks were delivered to 72 patients. Maximal energy (200 J) was used in 85% of shocks. Electrical cardioversion immediately restored sinus rhythm in 102 sessions (71%). Pretreatment with amiodarone did not increase the success rates. During the follow-up, the percentages of sinus rhythm decreased from 43% after 1 hour to 23% after 24 hours. However, at ICU discharge, 54 patients (75%) were in sinus rhythm. Of the 54 patients in sinus rhythm, only 18 (33%) converted to sinus rhythm after repeated cardioversions, whereas the remaining 36 (66%) did so spontaneously or with amiodarone. CONCLUSIONS Biphasic electrical cardioversion in cardiosurgical ICU patients was immediately successful in restoring sinus rhythm in 71% of sessions. However, early relapse of atrial fibrillation was common in the 24-hour follow-up. At ICU discharge, the majority of patients were in sinus rhythm, but the efficacy of repetitive electrical cardioversion in restoring sinus rhythm was disappointing.