Abstract 6090: Major Prognostic Impact of Persistent Microvascular Obstruction as Assessed by Contrast-Enhanced Cardiac Magnetic Resonance Imaging in the Setting of Reperfused Myocardial Infarction
To investigate the prognostic significance of microvascular obstruction (MO) and persistent microvascular obstruction (PMO) as assessed by Cardiac Magnetic Resonance Imaging (CMR) in patients with myocardial infarction (MI). CMR was performed in 184 consecutive patients during the week following successfully reperfused first MI. First-pass images were performed to evaluate presence or absence of MO and Late Gadolinium-enhanced images to assess extent of myocardial damage: regions of hyperenhancement, reflecting myocardial infarct size (IS) were manually contoured and expressed as a percentage of myocardial volume; regions of hypoenhancement, surrounded by hyperenhancement, reflecting PMO, were visually interpreted as present or absent. One-year follow-up was performed to collect the occurrence of Major Adverse Cardiac Event (MACE), as defined by cardiac death, non fatal recurrent MI, unstable angina or heart failure. MO was present in 127(69%) patients. PMO was present in 87 (46%) patients. Forty-four patients had MACE during the year following MI (including 5 cardiac death and 18 non fatal recurrent MI). By univariate logistic regression analysis, GRACE risk score>median (odds ratio [OR] 3.6; 95% confidence interval [CI] 1.8 –7.4; p<0.001), IS>10% (OR 2.7; 95%CI 1.1– 6.9; p=0.04) LVEF<40% (OR 2.4; 95%CI 1.1–5.2; p=0.03), presence of MO (OR 3.1; 95%CI 1.3–7.3; p=0.004) and presence of PMO (OR 10; 95%CI 4.1–23.9; p<0.001) were predictors of MACE. By multivariate regression analysis, only GRACE score>median (OR 2.8; 95%CI 1.3– 6; p=0.01) presence of MO (OR 2.5; CI 1.0 – 6.2; p=0.04) and presence of PMO (OR 8.7; 95%CI 3.6 –21.1; p<0.001) remained independent predictors of MACE. Kaplan-Meier curves showed that presence of either MO or PMO are associated with decreased event-free survival (p=0.008 and p<0.001, respectively). PMO was a best predictor of MACE when compared to MO (true positive: 44% versus 22%, respectively, p=0.001,). PMO as assessed by CMR is an independent predictor of worse outcome after MI, even stronger than MO.