Magnetic Resonance Imaging Delineates the Ischemic Area at Risk and Myocardial Salvage in Patients With Acute Myocardial Infarction

Background—The area at risk (AAR) is a key determinant of myocardial infarction (MI) size. We investigated whether magnetic resonance imaging (MRI) measurement of AAR would be correlated with an angiographic AAR risk score in patients with acute MI. Methods and Results—Bright-blood, T2-prepared, steady-state, free-precession MRI was used to depict the AAR in 50 consecutive acute MI patients, whereas infarct size was measured on gadolinium late-contrast-enhancement images. AAR was also estimated by the APPROACH and DUKE angiographic jeopardy scores and ST-segment elevation score. Myocardial salvage was calculated as AAR minus infarct size. Results are mean±SD unless specified otherwise. Patients were 61±12 years of age, 76% had an ST-segment elevation MI, and 20% had a prior MI. All underwent MRI 4±2 days after initial presentation. The relation between MRI and the APPROACH angiographic estimates of AAR was similar (overall size relative to left ventricular mass was 32±12% vs 30±12%, respectively, P=0.33), correlated well (r=0.78, P<0.0001), and had a 2.5% bias on Bland-Altman analysis. The DUKE jeopardy score underestimated AAR relative to infarct size and was correlated less well with MRI (r=0.39, P=0.0055). ST-segment elevation score underestimated infarct size in 19 subjects (50%) and was not correlated with MRI (r=0.27, P=0.06). Myocardial salvage varied according to Thrombolysis in Myocardial Infarction flow grade at the end of angiography/percutaneous coronary intervention (P=0.04), and Thrombolysis in Myocardial Infarction flow grade was a univariable predictor of myocardial salvage (P=0.011). In multivariable analyses, infarct size was predicted by T2-prepared, steady-state, free-precession MRI (P<0.0001). Conclusions—T2-prepared, steady-state, free-precession MRI delineates the AAR and enables estimation of myocardial salvage when coupled with a measurement of infarct size.