Background: Left ventricular ejection fraction (LVEF) is fundamental for risk stratification after ST-segment elevation myocardial infarction (STEMI). However, it lacks discrimination power within normal range. Novel echocardiographic deformation parameters may be of benefit for those with post-MI preserved LVEF. Objectives: We hypothesized that semiautomated calculation of baseline global longitudinal strain (GLS) can identify high-risk group among patients with LVEF ≥ 50% following STEMI. Methods: During the period from January to July 2017, 110 patients with successful reperfusion of STEMI and LVEF ≥ 50% were prospectively included. Within 48 hours, patients underwent a baseline GLS study with follow-up study at 30 days. The endpoint was a composite of cardiovascular mortality, rehospitalization for heart failure, and urgent revascularization. Results: Mean GLS value changed from −16 ± 4% at baseline to −12 ± 4% at 30-day follow-up (P < .001). At 30 days, cardiovascular mortality was reported in 4.5%, 11.8% were rehospitalized due to heart failure, and 5.4% underwent urgent revascularization. ROC curve analysis showed that a cutoff baseline GLS value >−12.65% predicted 30-day MACEs with a sensitivity and specificity of 77.8% and 83.7%, respectively (AUC 0.784, 95% CI 0.646–0.921, P < .001). An adjusted multivariate logistic regression analysis revealed that baseline GLS value >−12.65% to be the only significant independent predictor for occurrence of MACEs (OR 19.54, 95% CI 6.3– 61.1, P < .001). Conclusion: Early GLS calculation predicts 30-day outcome in patients with preserved LVEF following reperfusion of STEMI.