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The treatment of patients with ischemic cardiomyopathy is still problematic.The choice of revascularization of these patients especially who have substantial viability is not widely implemented due to confusion about its benefit. This work aimed to evaluate prospectively the response of left ventricular function to low as well as high dose dobutamine in patients with ischemic cardiomyopathy showing substantial viability , with and without improved resting left ventricular ejection fraction after coronary angioplasty. Fifty patients with ischemic cardiomyopathy(LVEF≤40%) and substantial viability(≥2segments) underwent low and high dose dobutamine echocardiography before and three months after percutaneous coronary intervention . Patients were divided into group 1, patients with, and group 2, patients without significant improvement in resting LVEF (> 5% by echocardiography) after revascularization. The response of LVEF during dobutamine stress echocardiography was compared in these two groups. Patients were matched for baseline characteristics except for the history of myocardial infarction which was more in group 2.The CCS functional class for angina and the NYHA functional class for heart failure were both improved after PCI in both groups but with a remarkable improvement in group 1.Myocardial viability increased much more in group 1 than group2 after PCI (6.3 vs. 4 viable segments before and 6.8 vs. 4.4 viable segments respectively after, p< 0.01).This result has an impact on LVEF in both groups.Resting, low dose and high dose dobutamine ejection fractions in group 1 as compared to group 2 were : 34% vs. 31%, 46% vs. 41% and 34% vs. 32% respectively, p<0.001 before PCI while they were : 43% vs. 31%, 54% vs. 44% and 56% vs. 46% respectively, p<0.001 after PCI. So, the improvement in LVEF (≥5%)was only found in group 1 and not in group 2. In conclusion, assessment of resting LV function has been used as the yard stick to evaluate the success of coronary revascularization in patients with ischemic cardiomyopathy and viable myocardium. The findings in the present study are similar with previous studies results and they show that assessment of resting LVEF is still beneficial to measure the improvement in left ventricular function after percutaneous coronary intervention. The LV function was improved only in patients with improved resting LVEF and improved myocardial viability after PCI.