Abstract 3014: Microvascular Obstruction by Cardiac Magnetic Resonance is a Stronger Predictor of Outcomes than left Ventricular Ejection Fraction or End-Systolic Volume Index after Primary Coronary Intervention

Abstract

Backgroud: Left ventricular (LV) end-systolic volume index (ESVI) and ejection fraction (EF) are predictor of long-term mortality following an acute myocardial infarction(AMI). However, interpretation of these parameters within 1 week of AMI is difficult due to myocardial stunning. We sought to correlate size of microvascular obstruction (MO), EF, and ESVI determined by cardiac magnetic resonance (CMR) to major cardiovascular events (MACE) after primary coronary intervention for ST-elevation MI (STEMI). Methods: CMR was performed in 94 consecutive STEMI patients within 1 week following AMI. The following indexes were calculated: size of MO/LV mass, infarct mass, EF, and ESVI. Patients were divided into two groups according to the size of MO: large MO group (MO/LV ≥ 0.1) and small MO group (MO/LV < 0.1). A three-year clinical follow-up was recorded. Univariate and multivariate analyses were applied to identify predictors of MACE. Results: The mean LVEF and ESVI were 43 ± 13% and 49 ± 15 ml. The mean infarct mass was significantly greater in large MO group than that in small MO group (28 ± 15g vs. 19 ± 10g p<0.01). Survival without MACE was significantly lower in patients with large MO group in comparison to those with small MO group (log-rank p<0.001). Large MO (1.98 [95% CI 1.2–2.0], p=0.001), EF (0.91 [0.90 – 0.97], p=0.007), and ESVI (1.04 [1.01–1.06], p=0.01) were the only independent predictors of MACE. However, Large MO was a strongest predictor of MACE by multivariate analysis. Conclusions: EF, ESVI, and size of MO predict the future cardiac events. Size of MO measured by CMR, which is independent of stunning, was stronger predictors of MACE than either of the other two parameters.