The role of timing in treatment of atrial fibrillation: An AFFIRM substudy

Background: In contrast to historical trials, the Early Treatment of Atrial Fibrillation for Stroke Prevention Trial (EAST-AFNET 4) suggests the superiority of early rhythm control over rate control in patients with recent-onset atrial fibrillation (AF). The relative contribution of timing vs improvement in AF therapeutics over time is unclear.

Objective: This study aimed to isolate the assessment of early intervention for AF from temporal changes in AF treatments through a secondary analysis of subjects from the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

Methods: We compared rate and rhythm control treatments in AFFIRM subjects stratified by time from their diagnosis of AF. Time-to-event analysis was performed to compare all-cause mortality, cardiovascular hospitalizations, stroke, and number of hospitalization days.

Results: Of the 4060 AFFIRM subjects, 2526 subjects (62.2%) had their first episode of AF within 6 months of study enrollment. Participants with "new" AF had a decreased risk of all-cause mortality (P = .001) than did those with prior AF diagnoses. Individuals previously diagnosed with AF were similar in age and demographic characteristics, but had more medical comorbidities, including myocardial infarction (P = .006), diabetes mellitus (P = .002), smoking (P = .003), and hepatic or renal comorbidities (P = .008). There were no differences in mortality, cardiovascular hospitalizations, or stroke between rate and rhythm control strategies in either AF subgroup.

Conclusion: AFFIRM subjects diagnosed with AF within 6 months of study enrollment showed no difference in survival, cardiovascular hospitalization, or ischemic stroke between rate and rhythm control strategies. Superiority of rhythm control strategies reported by newer AF trials may be more attributable to the refinement of AF therapies and less related to the timing of intervention.