Introduction: Mitral prosthetic thrombosis (MPV) is a rare but dangerous complication. It is suspected by clinical examination; the diagnosis of MPV is made by trans-thoracic echocardiography and held by the trans-esophageal echocardiography; or a fluoroscopy which shows a lack of prosthesis opening. The treatment is based on the early establishment of anti-coagulation and surgical cure. The thrombolysis is an alternative therapy. Case report: We report the case of a 47-year-old man who undergone a mitroaortic mechanical prosthesis replacement 6 years ago. However, since a year, his INR has been sub therapeutic. He presented a 5 days history of a chest pain and dyspnea. A passing at the intensive care diagnosed a shock according to the cool extremities, sweats, tachypnea and low blood pressure. The ECG showed atrial fibrillation with complete left bundle block. An emergency TTE was performed and revealed a MPV with high transvalvular gradient, while the aortic prosthesis was functional. The left ventricle was dilated and globally hypo contractile; TEE was emergently performed and showed à stuck leaflet caused by thrombus with associated with a thrombus at the left auricle. Patient’s hemodynamic condition required a surgical cure with thrombectomy of the left atrium. Conclusions: Through this case we highlight the interest of echocardiography to diagnose the etiology of shock, and the importance of early management to avoid any complications.