OBJECTIVES: Microvascular obstruction (MO) is associated with large acute myocardial infarction (AMI) and lower left ventricular (LV) ejection fraction, and predicts greater remodeling, but whether this effect is abolished by contemporary anti-remodeling therapies is subject to debate. We examined the influence of several infarct characteristics, including MO, on LV remodeling in an optimally-treated post-AMI cohort, using contrast-enhanced cardiac magnetic resonance (ceCMR).
METHODS: 100 patients (mean age 58.9Â±12 years, 77% male) underwent ceCMR at baseline (~4 days), 12 and 24 weeks. The effects on LV remodeling (i.e. change in LV end-systolic volume index [LVESVi]) of infarct site, transmurality, endocardial extent, and the presence of early and late MO were analyzed.
RESULTS: Mean baseline infarct volume index decreased from 34.0 (21.2) mL/m2 to 20.9 (12.9) mL/m2 at 24 weeks (p<0.001). Infarct site had no influence on remodeling, but greater baseline infarct transmurality (r=0.47, p<0.001) and endocardial extent (r=0.26, p<0.01) were associated with higher LVESVi. Early MO was seen in 69 (69%) of patients and persisted, as late MO, in 56 (56%). Patients with late MO underwent significantly greater remodeling than those without MO (LVESVi +4.1 [13.4] vs. -7.0 [12.7] mL/m2 respectively, p=0.001); those with early MO only displayed an intermediate LVESVi (-4.9 [13.0] mL/m2). Importantly, late MO was seen frequently despite optimal coronary blood flow having been restored at angiography.
CONCLUSIONS: Late MO on pre-discharge ceCMR remains an ominous predictor of adverse LV remodeling despite powerful anti-remodeling therapy, and may be useful in the risk-stratification of survivors of AMI. Haason Reddick Authentic Jersey