Abstract Approximately 50% of patients who survive an ST-segment elevation myocardial infarction (STEMI) experience irreversible damage to the heart muscle, which increases long-term risk of developing heart failure. Moreover, cardiovascular mortality constitutes half of all deaths. This research aimed to determine the best combination of patient data collected during a one-year follow-up period to enhance the accuracy of outcome predictions for patients with STEMI. Methods In this study, 246 patients who experienced STEMI and older than 18 were prospectively monitored. All participants received primary percutaneous coronary intervention treatment. The study's primary outcomes, observed over the year following hospital discharge, included cardiovascular death, recurrent myocardial infarction, newly diagnosed heart failure, and arrhythmias or conduction issues. Of the patients, 18% of patients reached the primary outcomes. Two-dimensional transthoracic echocardiography was conducted 3-5 days after the initial event to assess left ventricular global longitudinal strain (GLS) using 2D speckle-tracking echocardiography on the apical four-chamber, two-chamber, and long-axis views. Left ventricular mechanical dispersion was calculated as the standard deviation of the time from the Q/R wave onset to peak GLS across 17 segments of the left ventricle. Results The findings revealed that the overall GLS was -10.70 (-12.61 to -8.40), but in patients who met the study's primary outcomes, GLS was significantly lower at -7.83 (-8.70 to -6.90), compared to -12.02 (-13.11 to -10.17) in those who did not, with a significant difference (p=0.00001). Mechanical dispersion was 40.24±26.56 in the entire cohort but significantly higher at 65.62±22.57 in the outcome group compared to 25.79±14.81 in the non-outcome group (p=0.00001). The ejection fraction averaged 48.97±7.69% across all patients, 47.22±7.16% in those with outcomes, and 49.92±7.84% in those without, with a statistically significant difference (p=0.039). Cox regression analysis identified key predictors of major adverse cardiac events (MACE) within one year after STEMI, including global longitudinal strain (p=0.0006), left atrium volume index (p=0.0448), left ventricular end-diastolic diameter (p=0.045), and mechanical dispersion (p<0.0001). A multivariate logistic regression analysis demonstrated that a combination of GLS, left ventricular end-systolic volume (LVESV), mechanical dispersion, and ejection fraction could predict 1-year MACE with high accuracy (χ2 = 85.18; p<0.0001, AUC=0.961 [0.903-0.989]). In conclusion, this study identifies crucial metrics, such as global longitudinal strain, left ventricular end-systolic volume, mechanical dispersion, and ejection fraction, as predictive factors for MACE one year following STEMI. This predictive model is straightforward, reproducible, and can be easily implemented in cardiology practice.