Cooling in Myocardial Infarction

The primary goal in the treatment of acute myocardial infarction is to reperfuse the ischemic myocardium to reduce infarct size. Animal data and human data suggest that whole-body cooling to temperatures below 35°C before revascularisation can additionally reduce infarct size and therefore improves outcome in these patients.

The purpose of the study is to determine if a combined cooling strategy started in the out-of-hospital arena is able to reduce infarct size in acute myocardial infarction.

Background: Contemporary therapy in patients with an on-going ST-elevation myocardial infarction (STEMI) is to reperfuse the ischemic myocardium as soon as possible to reduce infarct size and associated complications. A recent pilot-study showed a significant reduction in infarct size by the induction of pre-reperfusion hypothermia.

Objectives: To demonstrate a reduction in infarct size/myocardium at risk (measured by magnet resonance imaging) in patients with ST-Elevation myocardial infarction by strategic temperature management with the use of external cooling pads in the out-of-hospital setting and the continuation with cold saline and central venous catheter cooling in hospital. In a parallel translational study, the molecular effects of rapid and early cooling on inflammatory processes at the culprit lesion site will be defined.

Methodology: Randomized, prospective, controlled trial Number of subjects: 120 patients (60 per group) Investigational medical device: EMCOOLS flex pad is an external cooling pad, that consists of multiple cooling cells filled with a patented cooling gel. EMCOOLS flex pad will be used in the out-of-hospital setting to initiate cooling. The Philips RTx Endovascular System™ is an endovascular thermal control system that circulates cooled saline through an indwelling central venous catheter in a closed-loop manner. It will be used in combination with 1-2 litres of intravenous cold saline to induce hypothermia below 35 degrees Celsius.

Duration: One hour after successful revascularization the cooling procedure will be stopped, subjects will be covered with a blanket and are allowed to passively re-warm. Clinical follow-up for 180 days.

Primary endpoint: Myocardial infarct size (as a percentage of myocardium at risk) assessed by cardiac MRI at 4±2 days. Influence of target temperature management on coronary macrophages and monocytes as well as impact on plasma levels of immune cell chemotaxis and activation.

Eligibility Criteria:
Inclusion Criteria:

* Age between 18 and 75 years
* Immediate transfer to cath-lab is possible
* Anterior or inferior ST-segment myocardial infarction
* ST-Segment elevation of \>0.2mV in 2 or more anatomically contiguous leads
* Duration of symptoms \<6 hours

Exclusion Criteria:

* Participation in another study
* Patients presenting with cardiac arrest/cardiogenic shock
* Tympanic temperature \<35.0°C prior to enrolment
* Thrombolytic therapy
* Previous MI
* Previous PCI or coronary artery bypass graft
* Severe heart failure at presentation (defined as a New York Heart Association (NYHA) functional class III or IV), or Killip classes II through IV
* Clinical signs of active infection
* End-stage kidney disease or hepatic failure
* Recent stroke (within the past six months)
* Conditions that may be exacerbated by hypothermia, such as haematological dyscrasias, oral anticoagulant treatment with international normalized ratio \>1.5, severe pulmonary disease
* Pregnancy
* Women of childbearing potential
* Allergy to meperidine, buspirone, magnesium, or polyvinyl chloride
* Use of a monoamine oxidase inhibitor such as selegiline in the previous 14 days
* absolute contraindications against MRI (PM, ICD, ferromagnetic implants)