Background: Coronary artery ectasia (CAE) is characterised as localised or widespread non-obstructive lesions of the epicardial coronary arteries with a luminal dilation more than 1.5 times the neighbouring normal segments or vessel diameter. Isolated CAE is CAE in the absence of severe coronary artery stenosis. This aberrant dilatation of coronary arteries can produce angina pectoris and even myocardial infarction in people without coronary artery disease owing to vasospasm, dissection, or thrombus. The purpose of this study was to evaluate the connection between                 CAE and major adverse cardiac events (MACE) following acute myocardial infarction with ST elevation. Methods: This was a prospective cohort study which was carried out on 300 cases. Cases were divided into two groups: Group I: including about 22 STEMI cases with CAE and Group II: including about 278 STEMI cases without CAE. All cases in this study were subjected to full history taking, clinical examination, laboratory tests, standard 12-leads ECG, resting transthoracic echocardiography (TTE), and coronary angiography. Results:  Regarding MACE in the studied groups, Incidence of reinfarction and cardiac death were significant higher in cases with STEMI and CAE than cases with STEMI alone. In univariate regression analysis, CAE (OR: 3.59, p value =0.022) was a significant predictor of cardiac death but age, male sex, and EF were not. Also, in multivariate regression analysis CAE (OR: 3.49, p value =0.029) was a significant predictor of cardiac death but age, male sex, and EF were not smoking with high warfarin consumption. Further, Markis classification 1 and 3 were the most frequent phenotype among cases. In STEMI cases, the incidence of reinfarction and cardiac death were significantly higher in cases with STEMI and CAE than cases with STEMI alone. So, CAE is a significant predictor of cardiac death.