New-onset versus prior history of atrial fibrillation: Outcomes from the AFFIRM trial Abdulla A. Damluji, MD, MPH, a Mohammed S. Al-Damluji, MD, MPH, b George R. Marzouka, MD, a James O. Coffey, MD, a Juan F. Viles-Gonzalez, MD, PhD, a Mauricio G. Cohen, MD, a Mauro Moscucci, MD, MBA, a Robert J. Myerburg, MD, a and Raul D. Mitrani, MD a Miami, FL and New Haven, CT 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. (Am Heart J 2015;170:156-163.e1.) Atrial fibrillation (AF) remains the most common cardiac arrhythmia particularly among the elderly population. 1 The incidence of new-onset AF increases with age, coronary artery disease, and systolic dysfunction. 2 Accordingly, it has been associated with increased risk of all-cause mortality, sudden cardiac death, and hospitalization. 3 The American College of Cardiology/American Heart Association/European Society of Cardiology 2006 Guide- lines for the management of patients with AF emphasized that clinicians should recognize the first detected episode of AF. 4 The 2014 Guidelines did not include this mandate to recognize first episode, suggesting lack of data regarding specific treatment for patients with the first detected episode of AF. Furthermore, patients with new-onset AF are significantly less likely to get anticoagulated than patients with prior AF despite the presence of stroke risk factors. 5 It is unknown whether differences exist in mortality, maintenance of sinus rhythm, or rate of ischemic stroke between patients with new-onset AF versus those with a prior history of AF. We sought to examine whether new-onset AF was associated with an increased risk of all- cause mortality or rate of ischemic stroke in a large cohort of patients treated with rate- versus rhythm-control strategies. In addition, we assessed whether patients with new-onset AF were more likely to remain in normal sinus rhythm (NSR) compared with patients with prior history of AF treated with rate- or rhythm-control strategies. Methods Study protocol Between March 1995 and September 2002, the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial (NCT00000556) recruited 4,060 patients with AF from 213 clinical centers across the United States and Canada. These patients were randomized in a 1:1 ratio to either a rhythm-control strategy or a rate-control strategy. The inclusion and exclusion criteria and specification medications used for both treatment strategies were previously reported. 6 From the a Cardiovascular Division, University of Miami Miller School of Medicine, Miami, FL, and b Department of Internal Medicine, Yale University School of Medicine, New Haven, CT. This is an original manuscript and has not has been previously published or submitted. Funding: No extramural funding was used to support this work. Conflict of interest disclosures: There are no conflicts relevant to this manuscript. Submitted September 10, 2014; accepted April 12, 2015. Reprint requests: Raul D. Mitrani, MD, FACC, FHRS, Cardiovascular Division, Department of Medicine, University of Miami Hospital, Miller School of Medicine, 1400 NW 12th Ave, Miami, FL, 33136. E-mails: RMitrani@med.miami.edu, adamluji@med.miami.edu 0002-8703 © 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ahj.2015.04.020