[Development of left atrial thrombus after excellent mitral valvuloplasty for chronic severe mitral regurgitation].

We report two cases with chronic severe mitral regurgitation and atrial fibrillation in whom left atrial thrombus was detected by transesophageal echocardiography after excellent mitral valvuloplasty. The reason why thrombus developed after valvuloplasty is that preoperative severe mitral regurgitation made the left atrial blood less stagnant than it was after surgery. Thus, even when mitral valvuloplasty achieves excellent results in patients with severe chronic mitral regurgitation and atrial fibrillation, anticoagulation and left atrial appendage ligation should also be considered.