Relapse and mortality following cardioversion of new-onset vs. recurrent atrial fibrillation and atrial flutter in the elderly.

AIMS: Trials of rate control vs. rhythm control for atrial fibrillation or flutter included few patients with new-onset arrhythmia. Our objective was to assess the relapse rate and the effect of the relapse of new-onset atrial arrhythmias on mortality after direct-current cardioversion (DCCV).

METHODS AND RESULTS: A cohort of 351 patients with atrial fibrillation (new onset in 179) and 126 patients with atrial flutter (new onset in 78) was followed-up after DCCV. Cox proportional hazard models were used. Median age was 74.6 years. Mean follow-up for relapse was 7.7 months; for death, 29.4 months. Patients with new-onset atrial flutter [adjusted hazard ratio (HR) = 1] were more likely to maintain sinus rhythm than the patients with recurrent atrial flutter (adjusted HR = 2.5, P < 0.01), new-onset atrial fibrillation (adjusted HR = 2.4, P < 0.01), or recurrent atrial fibrillation (adjusted HR = 2.7, P < 0.01). Patients with new-onset atrial fibrillation were as likely to have relapses as patients with recurrent atrial fibrillation or flutter. Relapse of atrial arrhythmia after DCCV was associated with increased mortality (adjusted HR= 3.1, P < 0.01).

CONCLUSION: DCCV is more successful in maintaining sinus rhythm in patients with new-onset atrial flutter than in patients with new-onset atrial fibrillation. Relapse of atrial arrhythmia after cardioversion is associated with increased mortality.