Zafrir B, et al. - Researchers assessed how long-term prognosis (up to ∼2.2 years) between acute and chronic heart failure (HF) with reduced (HFrEF < 40%), mid-range (HFmrEF 40%–49%), and preserved (HFpEF ≥ 50%) ejection fraction (EF) is influenced by atrial fibrillation (AF) vs sinus rhythm (SR). For this purpose, they analyzed data from 14,964 HF patients (age 66 ± 13 years, 67% male; 53% HFrEF, 21% HFmrEF, 26% HFpEF) in this observational, prospective, HF long-term registry of the European Society of Cardiology. Findings revealed that the prevalence of AF increased with the rise in EE; however, its association with worse cardiovascular outcomes remained substantial in patients with HFpEF and HFmrEF, but not in those with HFrEF.