This issue of Cardiology Clinics, guest edited by Drs. Benjamin A. Steinberg and Jonathan P. Piccini, will focus on Atrial Fibrillation in Heart Failure. Topics include, but are not limited to Epidemiology of Atrial Fibrillation and Heart Failure, Pathophysiology, Unmet clinical needs and future trials, Randomized clinical trials of catheter ablation for the treatment of Atrial Fibrillation/Heart Failure, AF ablation, role for digitalis, His-bundle pacing, Role of ivabradine for rate control, Novel Ablation Approaches for Challenging AF Cases, Imaging for risk stratification in AF/HF, Management of advanced left atrial myopathy, LV systolic function, patient-reported outcomes, Stroke prevention in AF and HF, Prediction and management of recurrences after catheter ablation in AF/HF, and Mechanisms of improved mortality following ablation.