Intracoronary Hypothermia as a Prevention of Reperfusion Injury in Myocardial Infarction.

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.

The study aims to find the most effective methods for the prevention and treatment of microvascular obstruction and reperfusion injury, studying the pathophysiological mechanisms of the development of this complication is of key importance. Many of these mechanisms are now known. In particular, the risk of developing microvascular obstruction is directly proportional to the duration of coronary artery occlusion, the degree of platelet aggregation activity, and blood viscosity and is higher in patients with massive thrombosis of the ischemic artery during percutaneous coronary intervention, which suggests a significant contribution to the development of microembolization during mechanical thrombus fragmentation. Despite all the collected data, there is no effective mode of reperfusion injury prophylaxis. Thus, it is necessary to explore new ways of minimizing reperfusion injury during primary percutaneous coronary intervention. The goal of our study is to determine the safety and effectiveness of intracoronary hypothermia. All patients who meet the eligibility criteria for this study will be randomized in a 1:1 ratio to receive intracoronary hypothermia with subsequent percutaneous coronary intervention or a standard revascularization strategy. The total number of patients planned to be recruited is 60. The study was approved by the local ethics committee. The intracoronary hypothermia group will receive 4°C normal saline with an infusion rate of 5 ml/min for 5 minutes through the inflated over-the-wire balloon, followed by an infusion of 4°C normal saline for 15 minutes with the same infusion rate of 5 ml per minute through the deflated over-the-wire balloon. After that, standard percutaneous coronary intervention is performed. The control group will receive only the standard percutaneous coronary intervention procedure.

Eligibility Criteria:
Inclusion Criteria:

* Acute ST-elevation myocardial infarction
* Time from onset of symptoms less than 12 hours
* Given informed consent

Exclusion Criteria:

* Contraindication to MRI
* Cardiogenic shock
* Conduction disturbance: Atrioventricular block: 2nd and 3rd degree. SA block.
* Sick sinus syndrome requiring implantable pacemaker
* Pulmonary edema
* Active inflammatory condition
* Active chemo/radiation therapy