It is a preliminary report with a quasi-experimental design, and with a pre-test and post-test approach to compare the effect of PCI in CTO patients. Forty subjects were recruited from January through June 2019. The inclusion criteria in this study were: 1) coronary heart disease (CHD) patients who showed CTO on coronary angiography that involved only one coronary artery branch occlusion; 2) patients who were willing to sign the informed consent of the study to undergo elective PCI; 3) patients who did not have heart failure abnormalities; 4) age between 40 and 70 years; 5) not in the acute phase of myocardial infarction; 6) not having abnormalities on the 12-lead electrocardiography (ECG) (signs of acute ischemia in the form of ST-elevation or ST depression); 7) left ventricular ejection fraction (LVEF) > 50%; 8) angiography with critical stenosis > 90%; and 9) normal valvular function. Based on the included samples, patients who were: 1) with multi-vessel disease; 2) with stage V renal failure requiring regular hemodialysis; 3) with malignancy; 4) with conditions that do not allow elective PCI intervention; and 5) with diastolic dysfunction (> grade 1) on echocardiography, should be excluded from the study sample.