We will perform a systemic review of previously published data and an updated patient-level meta-analysis of studies, including the most recent publications. PubMed, EMBASE, Cochrane Central Register of Controlled Trials, the United States National Institutes of Health registry of clinical trials, and relevant websites were searched for pertinent published studies.

This is an individual patient-level data meta-analysis (IPD Meta-analysis). This study population was incorporated from studies that were previoiusly published.

We will perform a systemic review of previously published data and an updated patient-level meta-analysis of studies, including the most recent publications. PubMed, EMBASE, Cochrane Central Register of Controlled Trials, the United States National Institutes of Health registry of clinical trials, and relevant websites were searched for pertinent published studies. The electronic search strategy was complemented by manual examination of references cited by included articles, recent reviews, editorials, and meta-analyses. No restrictions were imposed on language, study period, or sample size. The search keywords include "acute coronary syndrome", "ACS", "primary", "percutaneous coronary intervention", "PCI", "de-escalation", "guided", "guide", "antiplatelet", "P2Y12 inhibitor", "P2Y12", "dual antiplatelet therapy", "DAPT".

Articles were included when they met the following prespecified criteria: (1) included the ACS patients who underwent PCI with drug-eluting stent (DES); (2) maintained DAPT for 1 year; (3) de-escalation strategy of DAPT was clearly defined; (4) clinical outcomes, including ischemic and bleeding events, were clearly reported; (5) randomized controlled trials were considered for inclusion. Two independent investigators screened titles and abstracts, identified duplicated studies, performed full-article reviews, and determined the study inclusion. The third investigator supervised the searching process and adjudicated all the disagreements.

After selecting eligible RCTs, we will incorporate all known randomized controlled trials requesting individual patient data from the principal investigator of each trial.

This study is a meta-analysis of previously published studies. Therefore, the eligibility criteria may be diverse according to the individual studies.

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Inclusion Criteria:

• Subject must have clinical diagnosis of acute coronary syndrome

Exclusion Criteria:

• The patient has a known hypersensitivity or contraindication to any of the following medications: Heparin, Aspirin, Clopidogrel, Prasugrel, Ticagrelor

As above

Data sharing will be decided after discussed with the principle investigators of each study.