[Atrial thrombosis following the low-energy DC internal countershock of chronic AF: considerations of a clinical case].

Embolism may occur after cardioversion of atrial arrhythmias, especially atrial fibrillation, despite the apparent exclusion of preexisting atrial thrombus. This is related to the now well-known phenomenon of "atrial stunning" following either electrical or pharmacological cardioversion. It has also been suggested that "de novo" atrial thrombus formation after cardioversion could be responsible for the embolic event. We report a case of low-energy internal cardioversion of chronic atrial fibrillation in a patient with recurrent episodes of heart failure followed by a de novo left appendage thrombus formation. The patient, followed clinically and by repeated transesophageal echocardiograms, did not show any clinical sign of thromboembolism and the left appendage thrombus regressed completely, as demonstrated on the transesophageal echocardiogram.