Immediate Reinitiation of Atrial Fibrillation After Electrical Cardioversion Predicts Subsequent Pharmacologic and Electrical Conversion to Sinus Rhythm on Amiodarone Trudeke Van Noord, MD,, Isabelle C. Van Gelder, MD, Bas A. Schoonderwoerd, MD, and Harry J.G.M. Crijns, MD U p to 20% of patients with persistent atrial fibril- lation (AF) resist external electrical cardioversion either because the shock fails to terminate AF or because of immediate reinitiation of AF. In these resistant patients, antiarrhythmic drug pretreatment may enhance cardioversion. 1 In our institution, these patients undergo amiodarone loading followed by re- peated electrical cardioversion. It is important to know beforehand which patients will respond and in which patients this procedure will be futile. We hypothesised that immediate reinitiation of AF identifies patients in whom amiodarone loading and repeated electrical car- dioversion is successful in restoring and maintaining sinus rhythm. Therefore, our aim was to study in persistent AF patients with an unsuccessful electrical cardioversion whether immediate reinitiation of AF predicts subsequent successful conversion after amio- darone loading. In addition, we studied long-term maintenance of sinus rhythm in this group of patients. ••• We included 27 consecutive patients (9 women and 18 men) with an unsuccessful electrical cardioversion in whom the electrocardiogram could be adequately assessed immediately after the shock. During and the first 5 minutes after the electrical cardioversion pro- cedure, heart rhythm was carefully monitored by con- tinuous 12-lead rhythm recording. Electrical cardio- version was performed according to our previously described protocol, 2 which includes that a maximum of 5 shocks (at least 2 attempts with 360 J of stored energy) will be applied. After each shock, we inves- tigated whether immediate reinitiation of AF (2 minutes) occurred. 3 If 5 shocks of electrical cardio- version were unsuccessful (either there was no single sinus complex or patients had immediate reinitiation of AF), patients received amiodarone loading (600 mg/day during 4 weeks). After loading, electrical car- dioversion was repeated in patients who did not achieve conversion with amiodarone. In case of res- toration of sinus rhythm, amiodarone was continued (200 mg/day). An electrocardiogram was recorded after 1 month in all patients. A follow-up period of 1 month is considered appropriate for assessing the long-term arrhythmia outcome. 4 At the time of elec- trical cardioversion before inclusion, 11 patients had immediate reinitiation of AF, and in 16 patients no single sinus complex was seen. Mean age was 62  14 years. Median duration of persistent AF was 160 days (range 1 to 4,194), and median New York Heart Association class for heart failure was II (range I to III). There were no significant differences in baseline characteristics between patients with and without im- mediate reinitiation of AF. During loading, conversion occurred in 5 patients (46%) with immediate reinitia- tion of AF versus only 1 patient (6%) in the group without a single sinus complex (p = 0.027). A total of 10 (91%) versus 7 (44%) (p = 0.016) patients were in sinus rhythm after either pharmacologic or electrical cardioversion, respectively. After 1 month of fol- low-up 10 (91%) versus 5 (31%) (p = 0.0047) pa- tients were in sinus rhythm, respectively (Figure 1). ••• These findings show that in persistent AF resisting electrical cardioversion due to immediate reinitiation of AF, long-term maintenance of sinus rhythm may be achieved in most patients by administering amioda- rone and repeating cardioversion. By contrast, if no single sinus beat is observed during the electrical From the Department of Cardiology, Thoraxcenter, University Hospital Groningen, The Netherlands. Dr. Van Gelder’s address is: Department of Cardiology, Thoraxcenter, University Hospital Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands. E-mail: I.C.VAN.GELDER@THORAX.AZG.NL. Manuscript received March 30, 2000; revised manuscript received and accepted June 21, 2000. FIGURE 1. Percentage of patients in sinus rhythm in the 2 groups. ECV  electrical cardioversion; after first ECV  directly after unsuccessful ECV before starting amiodarone; after load- ing  after 30-day loading with amiodarone; after 1 month  1 month after repeat ECV; after re-ECV  directly after repeat car- dioversion with amiodarone; IRAF  patients with immediate reinitiation of AF after the first ECV; No SR  patients in whom no single sinus complex was seen during the first ECV proce- dure. 1384 ©2000 by Excerpta Medica, Inc. All rights reserved. 0002-9149/00/$–see front matter The American Journal of Cardiology Vol. 86 December 15, 2000 PII S0002-9149(00)01250-9