Importance of Both Early Reperfusion and Therapeutic Hypothermia in Limiting Myocardial Infarct Size Post–Cardiac Arrest in a Porcine Model

Abstract Objectives The aim of this study was to test the hypothesis that hypothermia and early reperfusion are synergistic for limiting infarct size when an acutely occluded coronary is associated with cardiac arrest. Background Cohort studies have shown that 1 in 4 post–cardiac arrest patients without ST-segment elevation has an acutely occluded coronary artery. However, many interventional cardiologists remain unconvinced that immediate coronary angiography is needed in these patients. Methods Thirty-two swine (mean weight 35 ± 5 kg) were randomly assigned to 1 of the following 4 treatment groups: group A, hypothermia and reperfusion; group B, hypothermia and no reperfusion; group C, no hypothermia and reperfusion; and group D, no hypothermia and no reperfusion. The left anterior descending coronary artery was occluded with an intracoronary balloon, and ventricular fibrillation was electrically induced. Cardiopulmonary resuscitation was begun after 4 min of cardiac arrest. Defibrillation was attempted after 2 min of cardiopulmonary resuscitation. Resuscitated animals randomized to hypothermia were rapidly cooled to 34°C, whereas those randomized to reperfusion had such after 45 min of left anterior descending coronary artery occlusion. Results At 4 h, myocardial infarct size was calculated. Group A had the smallest infarct size at 16.1 ± 19.6% (p