Quantification of myocardial area at risk with T2-weighted CMR: comparison with contrast-enhanced CMR and coronary angiography.

OBJECTIVES We sought to quantify the myocardium at risk in reperfused acute myocardial infarction (AMI) in man with T2-weighted (T2W) cardiac magnetic resonance (CMR). BACKGROUND The myocardial area at risk (AAR) is defined as the myocardial tissue within the perfusion bed distally to the culprit lesion of the infarct-related coronary artery. T2W CMR is appealing to retrospectively determine the myocardial AAR after reperfused AMI. Data on the utility of this technique in humans are limited. METHODS One hundred eight patients with successfully reperfused ST-segment elevation AMI were studied between 1 and 20 days after percutaneous coronary intervention (PCI). We compared the volume of hyperintense myocardium on T2W CMR with the myocardial AAR determined by contrast-enhanced CMR with infarct endocardial surface length (ESL) and AAR estimated by conventional coronary angiography with the BARI (Bypass Angioplasty Revascularization Investigation) risk score. RESULTS The volume of hyperintense myocardium on T2W CMR (mean 32 +/- 16%, range 3% to 67%) was consistently larger than the volume of myocardial infarction measured with contrast-enhanced images (mean 17 +/- 12%, range 0% to 55%) (p < 0.001). Myocardial salvage ranged from -4% to 45% of the left ventricular myocardium (mean 14 +/- 10%). The AAR determined by T2W CMR compared favorably with the infarct ESL (r = 0.77) with contrast-enhanced CMR, and there was moderate correlation between the BARI angiographic risk score and infarct ESL (r = 0.42). The time between PCI and CMR did not cause a significant difference in the volume of T2W hyperintense myocardium (r = 0.11, p = 0.27) or the calculated volume of salvaged myocardium (r = 0.12, p = 0.23). CONCLUSIONS T2W CMR performed early after successfully reperfused AMI in humans enables retrospective quantification of the myocardial AAR and salvaged myocardium.