Key Points A new ACS‐MCS risk score incorporating age, lactate, acute kidney injury, and SCAI Shock class predicts 30‐day mortality in patients receiving short‐term mechanical circulatory support for cardiogenic shock complicating acute coronary syndromes. This study illustrates that shock severity, as defined by SCAI Shock class, is one of multiple key factors influencing mortality in cardiogenic shock. Age and end‐organ injury are important mediators of cardiogenic shock outcomes.