Atrial fibrillation is the most common cause of inappropriate therapy deliveries by implantable cardioverter/defibrillators (ICD). However, the importance of atrial fibrillation for the induction of ventricular arrhythmias and for the prognosis is controversial. We studied 321 ICD patients (pts) over the median follow-up of 25 months. In 92 pts, atrial fibrillation was found to be the underlying rhythm (in 49 pts chronic, in 43 pts paroxysmal), in 229 pts sinus rhythm. Pts with atrial fibrillation were older (67 +/- 9 vs. 63 +/- 9 years, p = 0.001) and were considered to suffer more often from a valvular (14 vs. 4%, p = 0.004) or a dilative cardiomyopathy (29 vs. 19%, p = 0.04). Both groups were similar regarding other baseline characteristics like gender, left ventricular ejection fraction, hypertension, diabetes and in the ICD system (single chamber, dual chamber) used. Pts with atrial fibrillation experienced more appropriate (ventricular fibrillation: 0.33 vs. 0.2/month, p = 0.0049, ventricular tachycardias: 0.05 vs 0/month, p = 0.0033) as well as inappropriate (34 vs. 8%, p < 0.001) therapy deliveries by the ICD. Pts with atrial fibrillation were found to suffer twice as much from a progression of their heart failure (43% vs. 22%, p < 0.001). After multivariate analysis, atrial fibrillation was significantly associated with progressive pump-failure mortality (relative risk (RR) 3.12, confidence interval (CI) 1.30 to 7.48, p = 0.01). There was no difference in the incidence of ICD therapies and mortality rates between the pts with chronic and paroxysmal atrial fibrillation.
Conclusion: The presence of atrial fibrillation in ICD patients is associated with a progression of heart failure and therefore is an unfavorable factor for pump-failure death. Also, atrial fibrillation is a marker for greater possibility to experience more appropriate as well as inappropriate therapy deliveries by the ICD.