A 72-year-old woman presented with pulmonary edema. She had undergone mitral valve open commissurotomy 39 years earlier and a mechanical bileaflet mitral valve replacement 21 years later, and since then was treated with acenocoumarol. She had permanent AF, was highly compliant with her medications, and never had thrombotic or bleeding complications. Five months prior to her admission, her general practitioner switched her from acenocoumarol to dabigatran (110 mg bid) because of a single measurement of an INR above 5. One month later, she was admitted with dysarthria and mild hemiparesis and received a diagnosis of stroke, yet dabigatran was continued on discharge, and no cardiology consultation was requested. Three months later, she was admitted with severe pulmonary edema and shock. Cinefluoroscopy revealed a stuck anterior mitral leaflet, and transesophageal echocardiography revealed a large thrombus obstructing the mitral valve. She was sent to undergo immediate mitral valve replacement. A large occluding organized thrombus lining the atrial aspect of the prosthetic valve was discovered, and the valve was replaced with a biologic valve. Unfortunately, the patient died 3 days later of cardiogenic shock.