This report evaluated the correlates of sudden cardiac and nonsudden cardiac death in patients with persistent atrial fibrillation randomized to rate or rhythm control in the RAte Control vs Electrical cardioversion (RACE) study. Sudden cardiac death was observed in 16 patients, 8 patients in each group. Previous myocardial infarction resulted in a 4.9-fold increased risk of sudden death (95% confidence interval 1.8 to 13.2). The use of beta blockers showed their protective nature (hazard ratio 0.2, 95% confidence interval 0.05 to 0.9). The randomized treatment strategy, heart rhythm during follow-up, use of antiarrhythmic drugs, and number of stroke risk factors were not associated with sudden cardiac death. In conclusion, the treatment of underlying disease, rather than the heart rhythm, seems essential to prevent mortality.