Risk of Stroke, Thromboembolism and Mortality in Atrial Fibrillation Patients Across Different Stages and Types of Heart Failure: A Retrospective Cohort Study

Background/Objectives: Atrial fibrillation (AF) and heart failure (HF) frequently coexist and worsen prognosis. The risk of stroke and thromboembolism across HF stages and types in AF patients remains incompletely clear. To evaluate the risks of stroke, thromboembolism, and all-cause mortality in AF patients stratified by HF stages (A, B, C) and types, including HF with preserved ejection fraction (HFpEF), HF with mildly reduced ejection fraction (HFmrEF), and HF with reduced ejection fraction (HFrEF). Methods: We conducted a retrospective cohort study of 2134 AF patients in Beijing Tsinghua Changgung Hospital. HF stages were classified per American College of Cardiology/American Heart Association (ACC/AHA) guidelines, and HF types per European Society of Cardiology (ESC) criteria. Outcomes were assessed using Kaplan–Meier and multivariable Cox regression analyses. Results: Over a median follow-up of 32.4 months, the incidence of stroke, thromboembolism, and mortality increased from Stage A to B to C. Stage B showed higher rates than Stage A (stroke: 14.8% vs. 5.8%; thromboembolism: 19.1% vs. 8%; mortality: 4.0% vs. 1.2%). In Stage C, HFpEF had the highest incidence (stroke: 16.1%; thromboembolism: 22.3%; mortality: 10.3%). Adjusted models showed that the risks for all endpoints were significantly elevated in Stage B, HFpEF, and HFmrEF compared with Stage A. In contrast, HFrEF showed an elevated risk only for thromboembolism. Conclusions: Stage B HF was independently associated with higher risks of stroke, thromboembolism, and all-cause mortality in patients with AF. HFpEF showed the highest observed incidence of adverse outcomes among symptomatic HF phenotypes, suggesting that HF stage and phenotype may add prognostic value for AF risk stratification.