Atrial fibrillation after implantable cardioverter defibrillator implantation.

Atrial fibrillation is a reported complication of automatic defibrillator implantation. Its incidence, risk factors, time-course, and complications have not been well-defined. Accordingly, data from 117 patients who underwent defibrillator implantation via a thoracotomy (n = 71) or nonthoracotomy (n = 46) approach were reviewed. To identify risk factors, 15 variables of potential predictive value were chosen and analyzed. Atrial fibrillation developed in 26/117 patients (22%) during the early postoperative period and all but one of these 26 patients had undergone thoracotomy (P < 0.001). Patients who developed atrial fibrillation tended to be older than those who did not (63 +/- 2 vs 58 +/- 2 years, P = 0.04) and more frequently had a prior history of paroxysmal atrial fibrillation (31% vs 10%, P = 0.02). They were also less likely to be taking Class I or III antiarrhythmic drugs (1/26 vs 24/91, P = 0.01). By multivariate analysis, operative approach (P < 0.001), the absence of antiarrhythmic drug therapy (P = 0.006), and a prior history of atrial fibrillation (P = 0.003) were significant independent variables. Digoxin neither prevented the occurrence of atrial fibrillation nor slowed the maximal ventricular response. The mortality and complication rates did not differ between the two groups. The major adverse effect of postimplant atrial fibrillation was automatic defibrillator discharge; six patients received between 1 and 11 discharges for atrial fibrillation with rapid ventricular rates.