Through a single-center retrospective cohort study of acute ischemic stroke (AIS) patients receiving secondary prevention with indobufen, clopidogrel, cilostazol, or aspirin as monotherapy or dual therapy, we aim to compare the real-world effectiveness and safety of these four antiplatelet regimens. Through closely tracking the recurrence of stroke (including ischemic and hemorrhagic stroke) and bleeding events (GUSTO-defined) within one year of treatment, we evaluate the association between each antiplatelet agent and the risk of stroke recurrence, thereby providing critical evidence to guide individualized antiplatelet therapy in AIS patients.

Stroke is the second leading cause of death and the third leading cause of disability worldwide, with a 5%-10% one-year recurrence rate after acute ischemic stroke (AIS), making effective secondary prevention critical. Indobufen, aspirin, clopidogrel, and cilostazol-as monotherapy or in combination-constitute the main antiplatelet strategies for secondary prevention of ischemic stroke. Guidelines recommend early clopidogrel-aspirin dual therapy for mild stroke or TIA, while aspirin remains standard for moderate-to-severe cases, though it carries gastrointestinal and bleeding risks. Clopidogrel may be resistant due to CYP2C19 loss-of-function alleles in Asian populations. Cilostazol may be suitable for patients with CYP2C19-deficiency but has an uncertain intracranial bleeding risk. Indobufen, a reversible COX inhibitor, offers lower bleeding risk and fewer gastrointestinal adverse effects, yet lacks large-scale head-to-head trials against the other agents. Thus, real-world evidence to guide optimal antiplatelet selection for diverse ischemic stroke patients is lacking. This study aims to compare the effectiveness and safety of these four agents (monotherapy or guideline-recommended dual therapy) for secondary prevention of ischemic stroke, providing hypothesis-generating evidence for future prospective research.

Inclusion Criteria:

1. Age ≥ 18 years;
2. Diagnosed with acute ischemic stroke (AIS) patients according to the Chinese Guidelines for the Diagnosis and Treatment of Acute Ischemic Stroke 2018 ;
3. Hospitalized in the Department of Neurology, Nanfang Hospital, Southern Medical University, between January 2020 and December 2025;
4. Received one of the following as a secondary prevention regimen within 7 days after discharge: indobufen, aspirin, clopidogrel, or cilostazol, either as monotherapy or as dual therapy;
5. Have follow-up records at 1 year after treatment initiation.

Exclusion Criteria:

1. Already having long-term anticoagulant therapy at baseline;
2. History of hemorrhagic stroke or active bleeding;
3. Severe hepatic or renal dysfunction (defined as AST/ALT > 3 times the upper limit of normal, or estimated glomerular filtration rate < 30 mL/min/1.73m²), end-stage disease, intracranial tumor, or intracranial infection.

The study population mainly includes patients who meet the diagnostic criteria for acute ischemic stroke (AIS), are aged over 18 years, hospitalized in the Department of Neurology, Nanfang Hospital, Southern Medical University, between January 2020 and December 2025, received one of the following as a secondary prevention regimen within 7 days after discharge, and have follow-up records at 1 year after treatment initiation. Patients with long-term anticoagulant therapy at baseline, history of hemorrhagic stroke or active bleeding, or severe hepatic or renal dysfunction are excluded.