ObjectiveAcute myocardial infarction is a major cause of early cardiovascular morbidity and mortality, with arrhythmias contributing to adverse outcomes. This study evaluated the predictive utility of the baseline T wave peak-T wave end interval for arrhythmic events within 48 h in patients presenting with the first episode of acute myocardial infarction.MethodsIn this analytical cohort study, 196 patients with acute myocardial infarction were enrolled. Clinical characteristics, electrocardiographic findings, echocardiographic findings, angiographic findings, arrhythmias, complications, and in-hospital mortality were recorded.ResultsThe mean age of the patients was 62.1 ± 10.3 years, and 69.4% were male. Arrhythmias occurred in 65.3% of patients, most commonly ventricular tachycardia (21.8%). Multivariable logistic regression identified higher Killip class (III-IV) and prolonged T wave peak-T wave end interval as the independent predictors of arrhythmias. A T wave peak-T wave end cutoff ≥98 ms showed a sensitivity of 77.3%, specificity of 52.9%, and diagnostic accuracy of 69%. The T wave peak-T wave end and T wave peak-T wave end/QT ratios were significantly higher among nonsurvivors, along with greater clinical severity.ConclusionA prolonged baseline T wave peak-T wave end interval (≥98 ms) and higher Killip class independently predict early arrhythmias in acute myocardial infarction.