Acute myocardial infarction with ST segment elevation is often accompanied by a totally occluded coronary artery. Which has deleterious effects on heart muscle. Primary percutaneous coronary intervention is the most effective mode of treatment for ST-elevation myocardial infarction (STEMI) patients. Despite the restoration of the blood flow, 30-60% of patients develop microvascular obstruction, which lowers the effects of the coronary blood flow restoration. The most advanced coronary microvascular obstruction presents as a no-reflow phenomenon, which is an abrupt deceleration or absence of coronary flow following stent implantation. Several pharmacological treatments have been proposed, as well as deferred stenting, but none of them really helped. Thus, new ways of alleviating coronary obstruction are warranted. One of the new ways of mitigating the reperfusion injury is intracoronary hypothermia, which showed to be safe on a handful of patients in small series. In the animal studies, intracoronary hypothermia demonstrated a protective effect in terms of reducing infarct area. But clinical studies failed to reproduce the protective effects of intracoronary hypothermia. Thus, our study, using a modified hypothermia protocol, will test the hypothermia hypothesis.