Abstract

BACKGROUND: There are limited data on prognosis and outcomes of patients with new-onset atrial fibrillation (AF) compared with those with a prior history of AF. METHODS AND RESULTS: We conducted a comparison of these 2 groups in the AFFIRM trial. New-onset AF was the qualifying arrhythmia in 1,391 patients (34%). Compared with patients with prior history of AF, patients with new-onset AF were more likely to have a history of heart failure. There was no mortality difference between rate control (RaC) and rhythm control (RhC) among patients with new-onset AF (17% vs 20%, P = .152). In the univariate model, new-onset AF was associated with increased risk of mortality compared with history of prior AF (RaC unadjusted hazard ratio [HR] 1.36 [P = .010], RhC unadjusted HR 1.39 [P = .003]). However, after multivariate adjustments, new-onset AF did not carry an increased risk of mortality (RaC adjusted HR 1.14 [P = .370], RhC adjusted HR 1.16 [P = .248]). Subjects with new-onset AF randomized to the RhC arm were more likely to remain in normal sinus rhythm at follow-up (adjusted HR 0.79, P = .012) compared with patients with prior history of AF. CONCLUSIONS: In a multivariable analysis adjusting for confounders, new-onset AF was not associated with increased mortality compared with prior history of AF regardless of the treatment strategy. Patients with new-onset AF treated with the rhythm control strategy were more likely to remain in normal sinus rhythm on follow-up.