The Role of the Extracellular Volume of the Infarction Zone and the Remote Myocardium in Predicting Systolic Dysfunction After the First Myocardial Infarction

Background/Objectives: This study aimed to evaluate the prognostic role of the extracellular volume (ECV) assessed by cardiac magnetic resonance imaging (MRI) in relation to systolic dysfunction and unfavorable remodeling of the left ventricular (LV) at 24 weeks after myocardial infarction (MI) and revascularization. Methods: The study included 154 patients aged 56 ± 8 years who had been diagnosed with their first MI. Cardiac MRI was performed at 7–10 days and after 24 weeks, including assessment of indexed volumes, LV ejection fraction (LVEF), ECV, and patterns of ischemic and reperfusion injury. The study is registered in the international clinical trials registry with the number NCT04347434 (ClinicalTrials.gov). Results: Patients were divided into two groups after 24 weeks: group 1 (n = 24) with LVEF < 50% and group 2 (n = 130) with LVEF ≥ 50%. At 7–10 days, the scar mass in group 1 was 58.5 (39.5; 69.8) g vs. 17.1 (9.2; 29.7) g in group 2 (p < 0.001); microvascular obstruction was present in 23 cases (95.8%) vs. 55 (42.3%) (p < 0.001). After 24 weeks, inter-group differences increased (p < 0.05). Global ECV and remote myocardial ECV were significantly higher in patients with LVEF < 50% both at 7–10 days and after 24 weeks compared to those with LVEF ≥ 50% (p < 0.05). Infarct zone ECV did not differ between groups. Systolic dysfunction after 24 weeks was predicted by global ECV > 38.3% (p < 0.001) and remote myocardial ECV > 33.6% (p = 0.008). Predictors of an increase in end-diastolic volume index > 12% after 24 weeks in the subgroup of patients with initial systolic dysfunction were global ECV > 42.8% (p = 0.017) and remote myocardial ECV > 35.6% (p = 0.012). Conclusions: Global ECV and ECV of the remote myocardium, which exceed a certain level established by a cardiac MRI in the acute stage of MI, are among the predictors of LVEF < 50% and unfavorable LV remodeling in the medium term.