ABSTRACT Introduction Endovascular aortic arch repair (EAAR) and the endovascular reconstruction of arch branch vessels represent a new trend in managing aortic arch pathologies, due to advantages such as minimal invasiveness, rapid recovery, and fewer complications. However, stroke is a common and serious complication during EAAR procedures. Strategies for its prevention, including the question of whether antiplatelet therapy should be administered postoperatively, have not yet been reported.

Methods and analysis This project is designed as a prospective, multicenter, double-blind, randomized controlled trial. Patients undergoing Endovascular Aortic Arch Repair (EAAR) will be randomly assigned to three groups: aspirin treatment for 3 months, 6 months, or 1 year. All three groups will be followed up on for over one year. The primary endpoint is the incidence of postoperative stroke, while secondary endpoints include the patency rate of reconstructed supra-aortic branches, the incidence of major bleeding complications, EAAR-related complications, and the incidence of postoperative cognitive impairment. The study aims to evaluate the efficacy and safety of aspirin in preventing stroke after EAAR.

Furthermore, stratified analyses will be conducted based on factors such as reconstruction techniques, the number of reconstructed branch arteries, and the diameter of branch stents to explore their impact on stroke incidence post-EAAR. The clinical utility of aspirin in different subgroups will also be assessed to provide more precise and personalized treatment strategies for clinical practice.

Ethics and dissemination This study has been approved by the Western Theater Command General Hospital and will be conducted in accordance with the principles of the Declaration of Helsinki. Ethical approval has been obtained separately from all participating research centers.

STRENGTHS AND LIMITATIONS OF THIS STUDY Endovascular aortic arch repair (EAAR) and endovascular reconstruction of the aortic arch branches have emerged as a new trend in managing aortic arch pathologies, owing to advantages such as minimal invasiveness, rapid recovery, and fewer complications. Stroke is a common and serious complication during EAAR procedures; however, strategies for its prevention, including the need for postoperative antiplatelet therapy, have not been well documented.

This project aims to conduct a prospective, multicenter randomized controlled trial to evaluate the efficacy and safety of aspirin in preventing stroke following EAAR, thereby providing evidence for clinical decision-making and improving long-term patient outcomes. As the trial will be conducted in China, where the population is predominantly Han Chinese, the generalizability of the findings may be limited.

Inclusion Criteria:

1. Adult patients aged 18 years or older;
2. Diagnosed with type B or non-A non-B aortic dissection or thoracic aortic aneurysm according to the 2022 Chinese Expert Consensus on Stanford Type B Aortic Dissection;
3. Underwent total endovascular aortic arch repair at the participating center with concurrent intraoperative endovascular reconstruction of supra-arch branch arteries;
4. Signed the informed consent form and agreed to participate in this randomized controlled trial.

Exclusion Criteria

1. Patients with known allergies to aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs);
2. Patients with bleeding tendencies or active bleeding;
3. Patients who used medications affecting coagulation (e.g., warfarin, antiplatelet drugs) within 30 days before surgery;
4. Patients with a history of stroke;
5. Patients undergoing concurrent additional surgical procedures during the operation;
6. Patients with severe multi-organ dysfunction or other critical illnesses;
7. Patients unable to comply with study protocols or complete postoperative follow-up;
8. Patients participating in other drug or clinical studies that may interfere with the results of this research.

This study employs a double-blind method with a two-level blinding system. The core principle is the isolation of key roles and the withholding of information.

Blinding Personnel / Drug Managers: The blinding personnel or drug managers are aware that Drug A is the investigational drug (aspirin) and Drug B is the placebo; however, they have no contact with study participants and do not participate in efficacy or safety assessments.

Investigators / Assessors / Participants: Are responsible for the treatment, follow-up, and assessment of participants but are unaware of the specific identity of Drug A and Drug B (i.e., they do not know which is the investigational drug and which is the placebo).