Background: R-wave changes might be helpful in accurate diagnosis of coronary artery disease with exercise testing in combination with ST segment changes as ∆RST index and might be superior to the traditional ST segment depression only. Objective: To further clarify R-wave amplitude (RWA) changes during exercise stress test (EST) among established IHD patients. Patients and methods: The study enrolled 50 subjects - aged from above 35 to below 65 years old of both sexes, known to be ischemic by a previous angiography, divided into two main groups: Group I (control group): 15 subjects with normal coronaries (lesion < 30 % stenosis), and Group II (IHD group): 35 patients with stable ischemic heart disease which were subdivided according to previous coronary angiography results (lesion >70 % stenosis).The study was conducted at the Department of Cardiovascular Medicine and its Out-patient Clinic, Al-Hussein University Hospital during the period from September 2019 to March 2021.       ∆RST index was formed from algebraic summation of RWA difference between (rest and immediate recovery) plus ST segment depression in mile meters. Results: ∆RST index was more useful in detection of coronary artery disease with higher sensitivity and specify among chronic ischemic patients than RWA difference or ST segment depression alone. When cutoff ≥ -1.65 cardiac ischemia could be predicted with a sensitivity rate of 98.93%, a specificity rate of 96.00%, a positive predictive value of 96.3 %, and a negative predictive value of 98%. RWA at a cut-off point of   -1.2 was sensitive 95.02% and specific 94.0 % , a positive predictive value of 95.7%, and a negative predictive value of 96.6%. ST segment depression at a cut-off point of ≥ 0.45 was sensitive 77.1% and specific 80%, a positive predictive value of 78.4%, and a negative predictive value of 60.3%. Conclusion: ∆RST index was more useful in detection of coronary artery disease with higher sensitivity and specify among chronic ischemic patients than RWA difference or ST segment depression alone.