In patients with left ventricular output failure, the Impella left ventricular assist device increases total cardiac output despite a drop in output provided by the left ventricle itself. We present a patient with cardiogenic shock after myocardial infarction in whom an Impella recover 2.5 was implanted. Correct placement was ensured by fluoroscopy, pressure and current signals displayed on the console of the system, and transthoracic echocardiography. On follow-up, the Impella device was dislocated with the shaft of the device lying on the anterior mitral leaflet causing a functional mitral stenosis evident by an increased transmitral diastolic flow gradient. After removing the device, the patients' haemodynamics improved within minutes. Other than a mild regurgitation, mitral valve was without pathological findings. Although infrequent, this case shows a possible complication of the Impella ventricular assist device and highlights the importance of periodical echocardiographic surveillance, especially in patients who show a poor response to therapy.