Inclusion Criteria:  age range from 18 to 70 years. diagnosed with Chronic Coronary syndrome according to European association guidelines of 2019. Normal structural heart disease (as evident by 2D transthoracic echocardiography). in sinus rhythm.  Exclusion Criteria:  Patient with heart rate below 70 bpm at the start of treatment. Smokers. hyperthyroidism. Hypertensive patients Patient with bradycardia arrhythmia (sinus Bradycardia, advanced degree of heart block). history of Atrial fibrillation. history of Myocardial infarction, Previous PCI, or CABG. Patient with Valvular heart disease.