Background-Depression predicts prognosis in many cardiac conditions, including congestive heart failure (CHF). Despite heightened cardiac risk in patients with comorbid atrial fibrillation (AF) and CHF, depression has not been studied in this group. This substudy, from the AF-CHF Trial of rate-versus rhythm-control strategies, investigated whether depression predicts long-term cardiovascular mortality in patients with left ventricular ejection fraction Յ35%, CHF symptoms, and AF history who receive optimal medical care. Methods and Results-Depression symptoms (Beck Depression Inventory-II) were assessed in 974 participants (833 men