In spite of medical advances, cardiogenic and pulmonary shock are associated with high mortality and morbidity. The availability and use of acute or temporary mechanical support devices has grown over the years, with the goal of improving patient outcomes by temporarily providing support to allow time for organ recovery or for longer-term decisions including transition to durable therapies. A collaborative effort commissioned by the International Society of Heart and Lung Transplantation and the Heart Failure Society of America has developed this critically-needed guideline for the management of patients requiring acute mechanical circulatory support (MCS). The document covers definitions of cardiogenic and pulmonary shock, medical treatment and surgical interventions, management of patients supported with temporary devices, complications, special populations, and social and ethical dilemmas. The writing groups include multidisciplinary members from both societies with a focus on diversity in gender, geography, area of expertise and level of seniority. The target audience includes cardiologists, especially interventional and advanced heart failure, pulmonarycritical care specialists, intensivists, cardiothoracic surgeons, as well as referring providers.