(a) Size of area at risk (AAR) by SPECT. There was no difference in AAR between the different groups. (b) Infarct size (IS) measured by ex-vivo MRI as a percentage of area at risk (AAR) by SPECT in the two groups. Pre-reperfusion hypothermia causes a 43% relative reduction in infarct size compared to post-reperfusion hypothermia and by 39% compared to normothermia. (c) Infarct size (IS) measured by ex vivo MRI, expressed as a percentage of the left ventricular mass. (d) Microvascular obstruction measured by ex vivo MRI, expressed as a percentage of the infarct size. Pre-reperfusion hypothermia totally abolished microvascular obstruction. Post-reperfusion hypothermia significantly decreased the extent of micovascular obstruction compared to normothermia. (* = p < 0.05, ** = p < 0.01, *** = p < 0.001). Data are expressed as mean ± SEM.