Decompensated aortic valve stenosis is a life-threatening condition. Aortic valve replacement in patients with cardiogenic shock due to critical aortic stenosis is a high-risk procedure and is associated with increased operative mortality. We describe the clinical course of a patient who was transferred to our institution in cardiogenic shock and with multiple organ failure, due to decompensated aortic valve stenosis. The patient received the percutaneous left ventricular assist device TandemHeart which has been developed for short-term cardiac support. After hemodynamic improvement the patient underwent successful aortic valve replacement. The device was left in place until the patient had recovered from surgery. The excellent outcome suggests that a perioperative mechanical support might greatly improve the safety of aortic valve replacement in the presence of cardiogenic shock.