External Counterpulsation (ECP) is a non-invasive therapy using pressured cuff that is performed on patients with refractory stable angina pectoris to relieve symptoms and increase quality of life. In Indonesia, waiting time for getting coronary artery bypass grafting (CABG) procedure for revascularization treatment in stable angina pectoris patients is way longer than international recommendation which correlates with increase morbidity and mortality during the waiting time. Utilization of ECP for such patients who wait for CABG procedure is still unclear. The investigator aim to evaluate efficacy of addition of ECP compared with medical therapy alone for this population. The efficacy is evaluated using measurement from echocardiography result, treadmill test result, and clinical outcome. if applicable, examination of myocardial perfusion using nuclear examination will also be performed.