The primary objective is to describe the safety and tolerability of ticagrelor, by assessment of adverse events (characteristics, reporting rate, severity, relationship and risk factors), especially the bleeding events as defined in 8.1 and other serious adverse events (SAEs) during 1-year follow up in Chinese acute coronary syndrome (ACS) patients.

The trial is a multi-centre, prospective cohort, non-interventional study to be conducted in the department of cardiology from approximately 20 tier-2 or 3 hospitals, China. The study requires Chinese subjects aged over 18, diagnosed as ACS and treated with ticagrelor at least one tablet from the department of cardiology in the around 20 tier-2 or 3 hospitals. The subjects will be tracked up to 1 month after the discontinuation of ticagrelor for AE events and 1 year after enrollment for major cardiovascular events. This is an observational study. The prescribing doctor is in charge of prescribing or discontinuation ticagrelor. The investigator in an observational study may not intervene in the treatment. All 1000 subjects' related data will be collected

Inclusion Criteria:

• 1. Provision of informed consent prior to any study specific procedures 2. Chinese female or male aged at least 18 years 3. Index event of non-ST or ST segment elevation ACS. 4. Taken with ticagrelor at least one tablet before enrollment.

Exclusion Criteria:

-1. Participation in another clinical study with an investigational product during the last 6 months.

2. Previous enrolment in the present study; 3. Allergy or any other contraindication to ticagrelor as described in ticagrelor China PI.

Chinese subjects aged over 18, diagnosed as ACS and treated with ticagrelor at least one tablet from the department of cardiology in the around 20 tier-2 or 3 hospitals.