P.1. Supraventricular Arrhythmias: P.1.21 Efficacy of Cardioversion of Clinical Atrial Fibrillation Using a Standard Implanted Defibrillator Free

The purpose of this study was to evaluate the efficacy of a dual-coil, active-can implantable cardioverter-defibrillator (ICD) system, implanted for the treatment of ventricular arrhythmias, in cardioversion of spontaneous episodes of atrial fibrillation (AF).

The population was derived from 360 patients with icds implanted between July 1997 and June 2001. The study patients were 69 ± 8.9 years old, 83% were male, coronary artery disease was present in 78%, and a prior history of non-permanent AF was present in 54%. Beta blockers were used in 72% of patients and amiodarone in 27% of patients. The mean left ventricular ejection fraction was 31 ± 9%. Echocardiographic evaluation demonstrated moderate to severe left atrial enlargement in 41% of patients. Patients with permanent AF were excluded.

Atrial fibrillation resulted in an ICD discharge in 23 patients. Successful cardioversion occurred in 79% of episodes of AF with defibrillation energy of 30.5 ± 4.4 joules. In multivariate analysis, no patient characteristics, including left atrial size, ejection fraction, or concurrent use of beta blockers or amiodarone predicted success of cardioversion. Multiple discharges were delivered in 17% of these patients.

Standard dual-coil, active-can ICD systems are highly successful at converting spontaneous AF that occurs in the clinical setting. There were no specialized defibrillation coils or algorithms required. The use of discriminatory algorithms for prevention of multiple ICD discharges due to atrial arrhythmias needs to be balanced with the high success rate of cardioversion.