Prediction of left ventricular remodeling and analysis of infarct resorption in patients with reperfused myocardial infarcts by using contrast-enhanced MR imaging

Purpose: To prospectively evaluate the accuracy of clinical and cardiac magnetic resonance (MR) imaging parameters for predicting left ventricular (LV) remodeling by using follow-up imaging as reference standard, and to prospectively evaluate infarct resorption in patients with reperfused first myocardial infarcts. Materials and Methods: The study was approved by the institutional ethics committee and all patients gave written informed consent. In 55 patients (48 men, seven women; mean age +/- standard deviation, 56 years +/- 13), contrast material-enhanced and cine MR imaging were performed 5 days +/- 3 and 8 months +/- 3 after myocardial infarction (MI). Microvascular obstruction (MO) and infarct size were estimated at first-pass enhancement (FPE) and delayed enhancement (DE) MR, respectively. Remodeling was defined as an increase in LV end-diastolic volume index of 20% or higher at follow-up. Differences in continuous and categorical data were analyzed by using Student t test and Fischer exact test as appropriate. Results: Patients with remodeling (n = 13, 24%) had higher creatine kinase MB (P < .05), more anterior infarcts (P < .05), more often a reduced Thrombolysis in Myocardial Infarction flow (P < .05), larger infarct size at DE MR (P < .001), a greater extent of MO at FPE MR (P < .01), lower ejection fraction (P < .001) and higher LV end-systolic volume index (P < .01). Infarct size at DE MR was a powerful predictor for remodeling (odds ratio: 1.18, P < .001), demonstrating that the risk for remodeling increased 2.8 fold with each 10% increase in infarct size. Infarct size of 24% or more of LV area predicted remodeling with high sensitivity (92%), specificity (93%), and accuracy (93%). Infarct resorption was larger in patients with remodeling (P < .01). Conclusion: Infarct size 24% or more of the LV area constitutes an importance threshold to predict remodeling. Patients with remodeling develop disproportionate infarct resorption.