Angiographic validation of magnetic resonance assessment of myocardium at risk in non-ST-elevation myocardial infarction
AIMS Global angiographic scores have been developed to determine the extent of myocardium jeopardized by significant coronary stenosis. We adapted these scores to quantify the anatomic area at risk during acute myocardial infarction. We used contrast-enhanced magnetic resonance (CMR) infarct imaging to measure the portion of myocardium that developed necrosis within the so defined angiographic area at risk. METHODS AND RESULTS In 83 subjects presenting for primary percutaneous intervention, the myocardium at risk was estimated angiographically using the Myocardial Jeopardy Index (BARI) and a modified version of the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) scores. CMR was performed within a week to measure infarct size, infarct endocardial surface area (infarct-ESA), and infarct transmurality. As infarct transmurality increased, the infarct size closely approximated the myocardium at risk by angiography. In 35 subjects with transmural infarcts, the area at risk by BARI and APPROACH scores matched the infarct size (r = 0.90 and r = 0.92, P < 0.001). Additionally, BARI and APPROACH scores matched the infarct-ESA in all subjects independently of collateral flow and time to reperfusion (r = 0.90 and r = 0.87, P < 0.001). The presence of early reperfusion, collaterals, or both was associated with a progressive decrease in infarct transmurality (P < 0.001 for trend) with no difference in the infarct-ESA. CONCLUSION The myocardium at risk of infarction can be determined angiographically as validated in subjects with transmural myocardial infarcts. Salvage provided by early reperfusion or collaterals occurs by limiting infarct transmurality, thereby the extent of endocardial infarct involved also allows estimation of the myocardium at risk in patients presenting with STEMI.