Myotonic Dystrophy type 1 (DM1) is the most common muscular dystrophy in adult life characterized by muscle dysfunction and cardiac conduction abnormalities. Atrial fibrillation frequently occurs in DM1 patients. It’s related to the discontinuous and inhomogeneous propagation of sinus impulses and to the prolongation of atrial conduction time, caused by progressive fibrosis and fatty replacement of the myocardium. AF predisposes to a hyper-coagulable state and to an increased risk of thromboembolism. We report the first case of complete resolution of left atrial appendage thrombosis with oral dabigatran etexilate in a myotonic dystrophy type I patient with atrial fibrillation scheduled for transesophageal echocardiogram-guided direct current cardioversion.