Infarct tissue characteristics of patients with versus without early revascularization for acute myocardial infarction: a contrast-enhancement cardiovascular magnetic resonance imaging study

Abstract

Histopathological studies have suggested that early revascularization for acute myocardial infarction (MI) limits the size, transmural extent, and homogeneity of myocardial necrosis. However, the long-term effect of early revascularization on infarct tissue characteristics is largely unknown. Cardiovascular magnetic resonance (CMR) imaging with contrast enhancement (CE) allows non-invasive examination of infarct tissue characteristics and left ventricular (LV) dimensions and function in one examination. A total of 69 patients, referred for cardiac evaluation for various clinical reasons, were examined with CE-CMR >1 month (median 6, range 1-213) post-acute MI. We compared patients with (n = 33) versus without (n = 36) successful early revascularization for acute MI. Cine-CMR measurements included the LV end-diastolic and end-systolic volumes (ESV), LV ejection fraction (LVEF, %), and wall motion score index (WMSI). CE images were analyzed for core, peri, and total infarct size (%), and for the number of transmural segments. In our population, patients with successful early revascularization had better LVEFs (46 ± 16 vs. 34 ± 14%; P < 0.01), superior WMSIs (0.53, range 0.00-2.29 vs. 1.42, range 0.00-2.59; P < 0.01), and smaller ESVs (121 ± 70 vs. 166 ± 82; P = 0.02). However, there was no difference in core (9 ± 6 vs. 11 ± 6%), peri (9 ± 4 vs. 10 ± 4%), and total infarct size (18 ± 9 vs. 21 ± 9%; P > 0.05 for all comparisons); only transmural extent (P = 0.07) and infarct age (P = 0.06) tended to be larger in patients without early revascularization. CMR wall motion abnormalities are significantly better after revascularization; these differences are particularly marked later after infarction. The difference in scar size is more subtle and does not reach significance in this study.