Background/Objectives: Cardiac magnetic resonance (CMR) imaging provides a comprehensive assessment of myocardial injury after ST-segment elevation myocardial infarction (STEMI), yet the relative prognostic value of segmental infarct zone parameters compared with global indices for predicting left ventricular (LV) functional recovery remains incompletely defined. This study aimed to determine whether segmental infarct zone functional and structural CMR parameters provide prognostic information for LV functional recovery after a first STEMI treated with primary percutaneous coronary intervention (PCI). Methods: In this prospective single-center study, 93 patients with a first STEMI (median age 61 years; 77% male) underwent CMR at baseline (median 3 days post-PCI) and at a 6-month follow-up. The comprehensive CMR assessment included cine imaging for volumetric and feature-tracking strain analysis, T1 and T2 mapping, and late gadolinium enhancement (LGE) for infarct size (IS) and microvascular obstruction (MVO) quantification. The myocardial segments were classified as infarcted, adjacent, or remote based on the LGE distribution. The primary outcome was unfavorable LV functional recovery, defined as failure to achieve an absolute increase of >10 percentage points in the LV ejection fraction (LVEF) or a follow-up LVEF ≤ 50%. Results: At the 6-month follow-up, significant reverse remodeling was observed: the LVEF improved from 49.0% [40.7–52.4] to 55.8% [47.9–59.9] (p < 0.001), the LV end-systolic volume decreased from 91.8 mL [75.1–113.8] to 80.8 mL [61.9–108.3] (p = 0.005), and the relative IS decreased from 30.9% [18.9–45.5] to 19.0% [11.1–31.3] of LV mass (p < 0.001). At the follow-up, MVO was no longer detectable in any patient. Unfavorable functional recovery occurred in 17 patients (18.3%). In the multivariable analysis, the infarct zone circumferential strain (CS) was the strongest independent predictor of unfavorable recovery (OR 8.81; 95% CI 1.98–39.28; p = 0.004), followed by the relative IS (OR 4.02; 95% CI 1.03–15.73; p = 0.045) and a lower infarct zone post-contrast T1 (OR 4.40; 95% CI 1.12–17.36; p = 0.034). Conclusions: Segmental infarct zone characteristics—particularly circumferential strain, post-contrast T1, and infarct size—provide clinically relevant prognostic information for LV functional recovery after STEMI. The infarct zone CS offers incremental predictive value beyond its structural parameters, reflecting the residual contractile reserve and myocardial viability.

Background: Adverse left ventricular remodeling (ALVR) remains an important complication after ST-segment elevation myocardial infarction (STEMI) despite timely reperfusion therapy. Early circulating biomarkers reflecting thromboinflammatory and eicosanoid-related pathways may improve identification of patients at risk of unfavorable remodeling. Objectives: To investigate whether platelet count, 20-hydroxyeicosatetraenoic acid (20-HETE), 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE], and NETosis activity measured on the morning after reperfusion therapy are associated with serial cardiac magnetic resonance (CMR)-defined ALVR after first STEMI. Methods: In this prospective single-center study, 93 patients with first STEMI treated with reperfusion therapy, including primary percutaneous coronary intervention (PCI) in 87 patients and thrombolysis followed by PCI underwent baseline CMR at a median of 4 days after PCI and repeat CMR at 6 months. ALVR was defined as a ≥12% increase in both left ventricular end-diastolic volume and left ventricular end-systolic volume at follow-up. Fasting blood samples obtained on the morning after PCI were used to measure platelet count, 20-HETE, 15(S)-HETE, and NETosis activity. Univariable and multivariable logistic regression and receiver operating characteristic analyses were performed. A secondary exploratory analysis evaluated predictors of absolute improvement in left ventricular ejection fraction (LVEF) of ≥10%. Results: ALVR occurred in 19 of 93 patients (20.4%). Patients with ALVR had lower platelet count and lower 20-HETE levels at baseline. In the multivariable model, lower platelet count (OR 0.981, 95% CI 0.965–0.996; p = 0.015) and lower 20-HETE (OR 0.985, 95% CI 0.970–1.000; p = 0.047) were independently associated with ALVR, whereas urea was not significant. In receiver operating characteristic analysis, 20-HETE showed the highest discriminatory ability for ALVR (AUC 0.713, 95% CI 0.594–0.833; p < 0.001), followed by platelet count (AUC 0.670, 95% CI 0.546–0.794; p = 0.007). By contrast, 15(S)-HETE and NETosis activity were not significant discriminators in the primary analyses. Overall LV function improved during follow-up, with LVEF increasing from 49.0% to 56.0% (p < 0.001). In secondary exploratory analysis, higher HDL was independently associated with LVEF improvement of ≥10% (OR 7.84, 95% CI 1.26–48.99; p = 0.028). Conclusions: Lower platelet count and lower 20-HETE measured on the morning after PCI were independently associated with subsequent CMR-defined ALVR after first STEMI. Platelet count may serve as a simple, clinically accessible marker of risk, while 20-HETE suggests a potential role of eicosanoid-related pathways in remodeling process.