ST segment elevation myocardial infarction (STEMI) is the most severe form of acute coronary syndrome (ACS) that affects nearly 500,000 Americans each year and places a heavy clinical and financial burden on the healthcare system. STEMI treatment requires prompt reperfusion to limit myocardial injury (recommended time of less than 90 minutes from hospital arrival to therapy delivery or 90-minute door to balloon time). Mild hypothermia (MH), i.e., temperature ~34°C, provides cardio-protection and decreased infarct size following MI by reducing myocardial metabolic demand, free radical creation, and platelet aggregation. 3DT is developing a novel, catheter-based method of selective auto-retroperfusion (SARP) to deliver hypothermia to the cardiac region of interest.