Regression of warfarin-resistant left atrial appendage thrombus after ablation of atrial fibrillation and permanent pacing.

Atrial fibrillation is the most common rhythm disturbance and can also occur in absence of true cardiac disease. However, also in these cases, it can generate left atrial appendage thrombi with systemic embolic potential. A regular and well conducted anticoagulant therapy with dicoumarol derivatives, as indicated in these patients, is not always successful.