Myocardial Work Analysis in ST-Elevation Myocardial Infarction: Insights into Left Ventricular Ejection Fraction—A Pilot Study

(1) Background: Left ventricular ejection fraction (LVEF) is traditionally used to assess prognosis in acute ST-elevation myocardial infarction (STEMI) patients. However, LV myocardial work (MW), evaluated echocardiographically, offers additional prognostic information by considering loading conditions. (2) Methods: This prospective study investigated the prognostic value of MW indices in 119 consecutive STEMI patients treated with primary percutaneous coronary angioplasty, stratified into three LVEF categories: reduced (≤40%), mildly reduced (41-49%), and preserved LVEF (≥50%). Transthoracic echocardiography was performed before discharge, and the primary endpoint included heart failure hospitalization, ventricular arrhythmias, all-cause mortality and new acute coronary syndromes. (3) Results: Patients with preserved or mildly reduced LVEF had higher global longitudinal strain, global work index, global constructive work (GCW), and global work efficiency, as well as lower global wasted work (GWW), compared to those with reduced LVEF. GCW was the strongest predictor of adverse outcomes in the preserved LVEF group (AUC = 0.730, <i>p</i> = 0.035), while GWW demonstrated robust predictive performance in the reduced LVEF group (AUC = 0.787, <i>p</i> = 0.001). (4) Conclusions: MW indices, particularly GCW and GWW, provide significant prognostic value in distinct LVEF categories in STEMI patients. These findings indicate that MW enhances risk stratification and informs management in this patient population.