Impact of atrial fibrillation status on clinical outcomes in patients admitted with heart failure.

Background: Few studies comprehensively examine the association of atrial fibrillation (AF) status with rehospitalisation for adverse clinical outcomes in heart failure (HF) patients. Methods: Patients admitted with a primary diagnosis of HF between 1-July-2003 and 31-March-2021 were identified from the Australian New South Wales Admission-Patient-Data-Collection database and stratified by AF status (no-AF vs new-AF vs prior-AF) (end-of-follow-up: 31-March-2022). Multivariable Cox regression and Fine-Gray competing risk methods were used to assess the association of AF status with risk of MACE/all-cause mortality and rehospitalisation for non-fatal outcomes respectively. MACE was defined as all-cause mortality, admission for myocardial infarction, ischemic stroke, HF or coronary revascularisation (percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery), whichever occurred first. Results: The cohort comprised 152,638 admitted HF patients (median age: 80.4 years; 51.4 % males): 10.7 % New-AF; 37.0 % Prior-AF. During a median 1.24 years follow-up, compared to no-AF HF patients, new-AF and prior-AF patients had significantly higher rates of MACE (no-AF:78.5 % vs new-AF:81.7 % vs prior-AF:86.3 %) (both logrank P < 0.001). However, after adjusting for differences in baseline characteristics and admission year-groups, new-AF and prior-AF status had differential impact on MACE compared to no-AF patients (adjusted hazard ratio [aHR] = 0.93, 95 % confidence interval [CI] = 0.91-0.94; aHR = 1.14, 95 %CI = 1.13-1.16 respectively; both P < 0.001); results were similar for all-cause death. Rehospitalisation risk for most non-fatal clinical outcomes were significantly higher in HF patients with new-AF and prior-AF. Conclusion: This study shows AF status has a differential impact on clinical outcomes in patients admitted with HF. Drivers behind these differences require further elucidation.