A Multi-Center Study on the Metoprolol Optimal Dosing Pathway of Metoprolol Application in Chinese Patients With Acute Coronary Syndrome

Inclusion Criteria: * Aged 18 years or above; * Hospitalized due to acute coronary syndrome; * Able and willing to provide written informed consent and to comply with the study. Exclusion Criteria: * Cardiac shock; * Unstable heart failure; * Beta-agonist therapy on a continuous or intermittent basis; * Hypotension (BP\<90/60 mmHg) or bradycardia (HR\<50 bpm) with symptoms; * Sick sinus syndrome; * Ⅱ\~Ⅲ atrioventricular block; * Killip \>Ⅱ; * Suspected acute myocardial infarction with heart rate\<45 beats/min, P- R interval\>0.24 sec or systolic blood pressure \<100 mmHg; * Existing contraindication for metoprolol or allergic to metoprolol or any excipients; * Participation in another clinical study with an investigational product during the last 3 months; * Previous enrolment in the present study; * Subjects the investigator thinks not suitable for this study. E.g. cancer etc.; * Inability to sign the informed consent form; * Pregnancy or lactation.