We sought predictors of successful electrical cardioversion (ECV) and the effect of biphasic energy in patients considered candidates for rhythm control. The patients were drawn from a registry, which included prospectively 1355 consecutive patients with persistent atrial fibrillation who underwent ECV in 96 Spanish hospitals. Successful ECV was considered excluding patients with an early relapse. Factors related to successful cardioversion were evaluated using logistic regression with the patients segregated with respect to the use of monophasic or biphasic energy. Sinus rhythm was restored in 92% of the patients, of which, 5% had an early relapse. Thus, we considered that a successful ECV was achieved in 87% of patients. Body surface area was the only factor independently related to failure of the monophasic energy cardioversion (OR = 0.20; P = 0.001). No single factor was predictive of biphasic energy cardioversion failure. Biphasic energy was more effective in restoring sinus rhythm in patients with body surface area >2.05 m(2) (83% success in monophasic vs. 92% in biphasic; P = 0.02). Body surface area was the only factor related to the success of ECV, but only in patients treated with monophasic energy. Biphasic energy should be the technique-of-choice in patients with a large body surface area.
