Background: ST-elevation myocardial infarction (STEMI) is considered one of the commonest causes of morbidity and mortality all over the world. Nevertheless, survival following acute STEMI showed a considerable improvement as a result of increased symptom recognition, precise diagnosis in addition to effective timely reperfusion. Objective: To detect the significance of the reciprocal ST segment alterations in the early stage of acute myocardial infarction (AMI) and whether it is truly reciprocal or represents a distant ischemia that might be revealed by coronary angiography. Patients and methods: This study was conducted on 133 patients admitted to Al-Mokattam Health Insurance Hospital, with the diagnosis of acute STEMI treated with primary percutaneous coronary intervention (PPCI) during the period between November 2018 and December 2019. Results: Distant ischemia in patients with STEMI undergoing PPCI level was significantly higher in reciprocal ST segment depression (RSTD) group (p-value < 0.001). Besides, multivessel disease (MVD) was more prevalent in RSTD group (36.8% vs. 17.5%) in comparison with NRSTD group. The degree of mitral regurge (MR) was more severe among patients with RSTD (P value = 0.029). Mortality rate was more in patients with RSTD, six patients has passed away all of them had RSTD. Conclusion: The reciprocal changes (RC) caused by interaction of distant ischemia of non-infarcted coronaries and benign mirror electrical alterations, and it has a mortality effect. So, RSTD that was a simple ECG finding used as an indicator of patients at high risk who require a more aggressive approach.