5. Quality assurance plan 1)Diagnosis of ACS is according to the third universal definition.2)Before registry, a training program on study objectives, data collection, and ACS management is given to the primary investigator and related staff at each participating center.3)Henan institute of cardiology epidemiology will regularly monitored at least 10% of CRFs for accuracy against medical records. If the CRFs are not completed with 98% accuracy, all CRFs are considered unqualified and this staff will be retrained.4)Before entering into the computer, data is queried for invalid and illogical values by research staff in Henan institute of cardiology epidemiology. Participating centres who has the high error rate of data, and no change in 6 months shall be deemed abandoned automatically; participating centres who has the high quality of data will be issued a certificate to reward.5)Investigator meeting will be annually held to conclude the progress, solve existing problems and strengthen program training.