Uncommon intraventricular thrombus formation between the posterior mitral leaflet and the lateral left ventricular wall.

Transthoracic echocardiography demonstrated an intraventricular mass between the posterior mitral leaflet and the lateral left ventricular (LV) free wall in a 61-year-old man. Because of this uncommon localization an intracardial tumor, an endocarditis of the mitral valve or an intraventricular thrombus was suspected. Magnetic resonance imaging (MRI) ruled out an intracardial tumor and revealed a myocardial scarring of the LV free wall covered by an intraventricular thrombus by late gadolinium enhancement. MRI can distinguish subacute clots-which do not enhance after contrast material injection-from organized thrombi. The characterization of thrombi can be used to predict the risk of embolism, which is higher for subacute clots than for organized thrombi.