Concurrent Cardioversion of Atrial Fibrillation during ICD Shock Testing ANNINA S. VISCHER, M.D.,* MARCUS MUTSCHELKNAUSS, M.D.,*,† ¨ MICHAEL S. KUHNE, M.D.,* STEFAN OSSWALD, M.D.,* CHRISTIAN STICHERLING, M.D.,* and BEAT A. SCHAER, M.D.* From the *Division of Cardiology, University of Basel Hospital, Basel, Switzerland; and †Herzpraxis Aeschenvorstadt, Basel, Switzerland

Background: Many patients receiving an implantable cardioverter-defibrillator (ICD) also have atrial fibrillation (AF). Shock testing during ICD implantation carries a potential risk of cardioversion to sinus rhythm (SR) and thrombembolic events. We aimed to analyze the recurrence of AF after cardioversion to SR during ICD shock testing. Methods: A total of 555 consecutive patients referred to a tertiary hospital in Switzerland for ICD implantation or generator exchange between 02/2002 and 03/2010 were screened for AF. Fifty-seven patients who were in AF at the time of ICD shock testing were included. Results: Forty-four patients (77%) were successfully cardioverted from AF to SR. Type of AF (persistent, not permanent 64 vs 31% of cardioverted patients) was the only predictor. Thirty-nine patients (89%) experienced a recurrence of AF/atrial flutter after a median of 54 days (interquartile range 35–251 days). The only predictor for recurrence of AF was previous AF declared as permanent. No ischemic stroke occurred during hospitalization for the procedure. Conclusions: For patients in AF undergoing shock testing at the time of ICD implant, there is a high chance of cardioversion from AF to SR, but there is also a high risk of early recurrence. Decisions regarding long-term anticoagulation should not be based on the heart rhythm immediately following shock testing. (PACE 2015; 38:864–869) implantable cardioverter-defibrillator, atrial fibrillation, sinus rhythm, cardioversion, shock testing

Introduction Implantable cardioverter-defibrillators (ICDs) were initially used in survivors of sudden cardiac death.1,2 More recently, indications have expanded to include primary prevention in patients at high risk of arrhythmia, predominantly in patients with severe left ventricular systolic

Disclosures: Beat Schaer has served on the speakers’ bureau for Medtronic and Sorin. Michael Kuhne has served on the ¨ speakers’ bureau for Boston Scientific, St. Jude Medical, and Biotronik. AV and MM none. Stefan Osswald has served on the speakers’ bureau for Medtronic, Boston Scientific, Biotronik, and St. Jude Medical and has received unrestricted grants from Medtronic, Boston Scientific, Biotronik, and St. Jude Medical. Christian Sticherling has served on the speakers’ bureau for Medtronic, Biotronik, and Sorin and had scientific support from Medtronic, Biotronik, Boston Scientific, St. Jude Medical, and Sorin. Address for reprints: Beat Schaer, M.D., Department of Cardiology, University of Basel Hospital, Petersgraben 4, 4031 Basel, Switzerland. Fax: 41-61-265-45-98; e-mail: [email protected] Received December 10, 2014; revised March 25, 2015; accepted March 27, 2015. doi: 10.1111/pace.12644

impairment.3–6 In both settings, the use of an ICD has been shown to significantly reduce mortality. In large randomized trials, 9–27% of patients were in atrial fibrillation (AF) at the time of ICD implant.3,4,6,7 Internal cardioversion of AF may be used as an alternative to external cardioversion and has been described to have a better acute success rate.8–13 Restoration of sinus rhythm (SR) during ICD testing in patients with AF carries the potential risk of thromboembolic complications.14,15 On the other hand, successful cardioversion might reduce the rate of inappropriate ICD therapy as patients with AF are at higher risk for inappropriate ICD shocks.7,16 Patients with permanent AF also have a higher risk of ventricular arrhythmias and a higher overall mortality.7 In cardiac resynchronization therapy (CRT) AF decreases the efficacy of biventricular pacing due to intrinsic conduction in patients without atrioventricular block.17,18 The aim of this study was to analyze the shortand long-term freedom from recurrent AF after cardioversion to SR during ICD shock testing at the time of ICD implantation, and the safety of shock testing in the context of AF.

©2015 Wiley Periodicals, Inc. 864

July 2015

PACE, Vol. 38

CARDIOVERSION OF ATRIAL FIBRILLATION WITH ICD

Methods Case records for all patients undergoing ICD implantation or generator exchange at a single tertiary center in Switzerland between 02/2002 and 03/2010 were reviewed. All patients with AF at the time of ICD implantation were identified. AF was documented by 12-lead electrocardiogram (ECG) recorded prior to ICD implantation. ICD implantation was performed with a standard approach using local anesthesia and conscious sedation (Midazolam, Fentanyl, Etomidate) for surgery and shock testing. Oral anticoagulation was usually stopped 2 days prior to ICD implantation with the intention of an international normalized ratio (INR) of 2.0– 2.5. Bridging with low-molecular-weight heparin (LMWH) was performed only if INR was

Concurrent Cardioversion of Atrial Fibrillation during ICD Shock Testing.

Many patients receiving an implantable cardioverter-defibrillator (ICD) also have atrial fibrillation (AF). Shock testing during ICD implantation carr...
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