The investigators have identified underuse of secondary prevention medications at discharge of patients underwent coronary artery bypass grafting (CABG) in China. The aim of this study is to develop series of quality improvement strategies focusing on secondary prevention medications for patients underwent CABG, and to evaluate their effectiveness and safety via a hospital-level cluster randomized clinical trial. The investigators established a network of 60 hospitals which have participated into Chinese Cardiovascular Surgery Registry and submitted 50 or more CABG surgeries already. The participating sites will be divided into intervention and control groups in a 1:1 ratio. The intervention group will undertake intervention of quality improvement strategies, while the control group will maintain the routine practice pattern. All hospitals will consecutively enroll and submit data of CABG during the enrollment period, estimated for 6 months. The prescribing rates of angiotensin converting enzyme inhibitor (ACEI), angiotensin receptor blocker (ARB), beta-blockers, statins and aspirins will be compared between 2 groups.

The investigators have identified underuse of secondary prevention medications at discharge of patients underwent coronary artery bypass grafting (CABG) in China. The aim of this study is to develop series of quality improvement strategies focusing on secondary prevention medications for patients underwent CABG, and to evaluate their effectiveness and safety via a hospital-level cluster randomized clinical trial. The investigators established a network of 60 hospitals which have participated into Chinese Cardiovascular Surgery Registry and submitted 50 or more CABG surgeries already. The participating sites will be divided into intervention and control groups in a 1:1 ratio. The intervention group will undertake intervention of quality improvement strategies, while the control group will maintain the routine practice pattern. All hospitals will consecutively enroll and submit data of CABG during the enrollment period of estimated 6 months. The prescription rates of ACEI, ARB, beta-blockers, statins and aspirins will be compared between 2 groups.

Before the enrollment period, the investigators have developed series of quality improvement strategies focusing on secondary prevention medications for patients underwent CABG, including training with guidelines of secondary preventions, determining improvement goals with participating sites, intervention tools (workflow posters and cards, checklists to inform the use of secondary prevention medications) and periodical quality feedback reports.

In the enrollment period, participating hospitals will be divided into intervention and control groups in a 1:1 ratio using minimization allocation.

The investigators will collect data on the prescription rates from central medical record abstraction, case report forms submitted by participating sites and checklists submitted by intervention groups.

Inclusion Criteria:

• Patients underwent CABG during the enrollment period in participating sites

Exclusion Criteria:

• Patients who die during hospitalization
• Patients who withdrawn from hospital against doctors' recommendations
• Patients who transfer out to other medical care institutions without discharge prescription

Outcomes assessor and data extractors were blind to the results of randomization