Atrial mechanical performance after internal and external cardioversion of atrial fibrillation: an echocardiographic study.

OBJECTIVES: To compare the time course of resumption of mechanical performance of the left and right atrium after the novel method of internal low-energy cardioversion (CV) and conventional external CV of atrial fibrillation (AF). BACKGROUND: Right atrial performance has been shown to normalize before the left atrium after external CV. However, no data on atrial function after internal CV are available. PATIENTS AND INTERVENTIONS: Sixty-three patients with chronic AF were randomized to participate in either external or internal CV. MEASUREMENTS: Echocardiographic examinations were carried out before as well as immediately after CV (day 0), and at days 1, 7, and 28 thereafter for the determination of cardiac dimensions, volumes, and transvalvular flow patterns. RESULTS: After randomized internal CV or external CV, stable sinus rhythm was restored in 59 patients. Irrespective of the mode of CV, the right atrium resumed its mechanical function immediately after CV, whereas the left atrium was stunned beyond day 7. The mode of CV, internal or external, had no influence on the recovery of atrial mechanical function. CONCLUSIONS: The right atrium resumes its normal function immediately after internal as well as external CV, whereas left atrium function is delayed. In contrast to the assumption that low-energy internal CV would impact less on atrial mechanical recovery, the type of method of CV used has no effect on such recovery.