Atrial fibrillation and heart failure (HF) frequently coexist and are associated with a significant increase in morbidity and mortality. Despite the shared common risk factors atrial fibrillation and HF subtypes exacerbate each other. This review provides an overview of the pathophysiologic relationship between atrial fibrillation and the two most common types of heart failure syndromes: HF with reduced ejection fraction and HF with preserved ejection fraction.