Abstract Background Of all causes of Cardiovascular disease (CVD), ischemic heart disease (IHD) remains the major contributor, accounting for half of all CVD-associated morbidity and mortality. IHD as measured by the Global Burden of Disease project is driven predominantly by acute myocardial infarction (MI) and, to a lesser extent, angina. Aim of the Work To evaluate the prognostic utility of the ratio of SBP/LVEDP at the time of PPCI in prediction of MACE both in-hospital and during 3-months follow up in patients presented with STEMI with a single vessel disease. Patients and Methods This was a prospective study that was conducted on 153 patients presented with STEMI and underwent successful PPCI for a single vessel disease in Ain-Shams University Hospitals and Nasr City Health Insurance Hospital in the period from March 2019 to March 2021. Results Our results demonstrated, that SBP/LVEDP ratio can be used to predict MACE occurrence at a cutoff level of ≤ 3.9, and can be used to predict patients who are MACE-free at cutoff level of ≥ 9.2. The lower ratio of SBP/LVEDP (≤3.9) was detected at 27 patients (17.6%) from the whole study population (153 patients) with higher statistical significance difference of older age group. Different risk factors and positive family history showed no statistical significance difference with lower ratio. In this study, lower ratio showed higher statistical significant difference in anterior STEMI group, lower EF% “Simpson”, higher LVESV, DD grade II, higher WMSI, with the culprit lesion vessel when its LAD, with higher LVEDP, lower invasive SBP, and lower invasive DBP. This study found that lower ratio had a better prognostic ability with a higher AUC (0.880) when compared to the widely used GRACE and TIMI risk scores. Lower ratio ≤3.9 showed higher statistical significant difference with higher GRACE RS and higher TIMI RS when compared with higher ratio. Our ratio had a strong prognostic ability in prediction of MACE with lower ratio with higher statistical significant difference of occurrence of MACE in 26 patients (96.3%, P = 0.000) when compared with patients with the same ratio but without occurrence of MACE in 1 patient (3.7%). Conclusion Our study concluded that SBP/LVEDP is an easily rapidly determined ratio at the time of PPCI that can provide important prognostic information regarding risk stratification of STEMI patients, with a high predictive ability for occurrence of MACE at a cutoff point of ≤ 3.9, during hospital stay and short term follow up.