External cardioversion of atrial fibrillation and flutter in patients with cardiac implantable electrical devices.

External cardioversion in patients with contemporary pacemakers and implantable cardioverter-defibrillators seems safe in the majority of patients. Clinically important changes in device function following cardioversion were rarely observed but may be critical for device function. In an observational study, causality between cardioversion and device dysfunction cannot be established. For patient safety, we suggest that routine device interrogation after cardioversion still should be part of standard care.