Association between atrial fibrillation and appropriate implantable cardioverter defibrillator therapy: Results from a prospective study

Introduction: Atrial fibrillation (AF) is associated with significant morbi dity and mortality that may be related to hemodynamic impairment, thromboem bolic events, or enhanced electrical instability of the ventricular myocard ium. There is, however, a lack of data concerning the association of AF and ventricular tachyarrhythmias, Methods and Results: Consecutive patients with indication for an implantabl e cardioverter defibrillator (ICD) were classified for the presence or abse nce of persistent AF at the time of device implantation, Incidence of devic e therapy, stored electrograms, and clinical events during follow-up were e valuated prospectively. Two hundred fifty patients were included. During fo llow-up (20 +/- 14 months), patients in AF experienced appropriate device t herapy for recurrent ventricular arrhythmias more frequently compared with patients in sinus rhythm (SR) (63% vs 38%, P = 0.01). On multivariate analy sis, AF was an independent predictor of appropriate ICD therapy (relative r isk 1.8; 95% confidence interval [CI] 1.2 to 2.9) and inappropriate device therapy (relative risk 2.3; 95% CI 1.2 to 4.5). Predefined clinical events (cluster endpoint: death, syncope, and hospitalizations) were observed more frequently in AF than in SR patients (55% vs 31%, P = 0.01). Analysis of d evice-stored electrograms revealed a higher incidence of short-long-short c ycles preceding ventricular arrhythmias in AF compared with SR patients (50 % vs 16%, P = 0.002). Baseline heart rate preceding ventricular arrhythmias did not differ between the two groups. Conclusion: AF is an independent predictor of recurrent ventricular arrhyth mias in ICD recipients. The underlying electrophysiologic mechanism seems t o be irregular rather than rapid ventricular activation, with a high incide nce of short-long-short sequences preceding ventricular tachyarrhythmias in AF patients.