Aims: Prevalent atrial fibrillation (AF) is associated with excess cardiovascular (CV) death (D) and hospitalizations (H) in heart failure (HF) with preserved ejection fraction (pEF). We evaluated if it had an independent role in excess CVD in HFpEF and studied its impact on cause-specific mortality and HF morbidity.

Methods and results: We used propensity score-matched (PSM) cohorts from the TOPCAT Americas trial to account for confounding by other co-morbidities. Two prevalent AF presentations at study entry were compared: (i) subjects with Any AF event by history or on electrocardiogram (ECG) with PSM subjects without an AF event and (ii) subjects in AF on ECG with PSM subjects in sinus rhythm. We analyzed cause-specific modes of death and HF morbidity during a mean follow-up period of 2.9 years. A total of 584 subjects with Any AF event and 418 subjects in AF on ECG were matched. Any AF was associated with increased CVH [hazard ratio (HR) 1.33, 95% confidence interval (CI) 1.11-1.61, P = 0.003], HFH (HR 1.44, 95% CI 1.12-1.86, P = 0.004), pump failure death (PFD) (HR 1.95, 95% CI 1.05-3.62, P = 0.035), and HF progression from New York Heart Association (NYHA) classes I/II to III/IV (HR 1.30, 95% CI 1.04-1.62, P = 0.02). Atrial fibrillation on ECG was associated with increased risk of CVD (HR 1.46, 95% CI 1.02-2.09, P = 0.039), PFD (HR 2.21, 95% CI 1.11-4.40, P = 0.024), and CVH and HFH (HR 1.37, 95% CI 1.09-1.72, P = 0.006 and HR 1.65, 95% CI 1.22-2.23, P = 0.001, respectively). Atrial fibrillation was not associated with risk of sudden death. Both Any AF and AF on ECG cohorts were associated with PFD in NYHA class III/IV HF.

Conclusion: Prevalent AF can be an independent risk factor for adverse CV outcomes by its selective association with worsening HF, HFH, and PFD in HFpEF. Prevalent AF was not associated with excess sudden death risk in HFpEF. Atrial fibrillation was also associated with HF progression in early symptomatic HFpEF and PFD in advanced HFpEF.

Trial registration: TOPCAT trial is registered at www.clinicaltrials.gov:identifier NCT00094302.