Researchers investigated the link between atrial fibrillation (AF) and mortality, as well as the association between resting heart rate (HR) and mortality in both sinus rhythm (SR) and AF among 9,090 patients with heart failure with preserved ejection fraction (HFpEF; ejection fraction ≥ 50%) from the Swedish Heart Failure registry. The investigators noted an independent association of AF with all-cause mortality. They also observed an association of a higher HR with increased mortality in SR. In AF, the impact of a higher HR on mortality was only present during the first years of follow-up, with convergence in outcomes according to baseline HR groups over long-term follow-up.