Evaluation of Succinate Metoprolol on Heart Rate in the Stable Angina Patients

Inclusion Criteria: * Provision of informed consent prior to any study specific procedures * Chinese patients * Heart rate ≥ 65bpm * Has been diagnosed as Stable angina for at least 1 month and with stable angina pectoris symptoms within 2 weeks previous to enrolment(Please find the diagnose criteria of Stable angina on Appendix C) * With Left ventricular ejection fraction ≥ 50% according to ultrasound cardiogram; * Has been on beta-blockers for at least 4 weeks\*, on the dose equivalent to Betaloc ZOK® 23.75-47.5mg/day. Exclusion Criteria: * Acute myocardial infarction within 6 months * Unstable angina or Prinzmetal's angina * II degree of AV block or greater * Significant clinical, laboratory or electrocardiographic abnormalities that would place the subject at undue risk (in the Investigator's opinion) including: * Significant renal impairment (serum creatinine \> 2.0 mg/dL) * Serum Alanine Aminotransferase or Aspartate Aminotransferase \> 3 x upper limit of reference range * Serum potassium \< 3.0 mEq/L * Serum sodium ≤ 130 mEq/L * Acute or chronic hepatitis or cirrhosis (clinical diagnosis) * Uncontrolled hyperthyroidism (clinical diagnosis) * Systolic blood pressure ≥ 180 mmHg, or \< 100mmHg at enrolment * Patients with unstable, not compensated heart failure (pulmonary oedema, hypoperfusion or hypotension)