In a 72-year-old male patient an acute coronary syndrome (ACS) was complicated by left ventricular aneurysm and severe mitral regurgitation. Two-dimensional echocardiography failed in detecting mechanism of mitral regurgitation. Transthoracic three dimensional echocardiography allowed us to obtain a better visualization of the relationship between papillary muscles, ventricular walls and mitral leaflets and dynamic systolic displacement of the posterior papillary muscle associated with restriction of both leaflets with greater apical tethering of anterior leaflet (A3-A2 scallops). Echocardiography performed after cardiac surgery revealed that ventricular reshaping after posterior papillary muscle realignment allowed the mitral regurgitation resolution.