Evaluation of Coagulation Factors and Platelet Activation in Patients Undergoing Complex Endovascular Para-Renal and Thoraco-Abdominal Aneurysm Repair: The Protocol of a Prospective Observational Study

Background/Objectives: Endovascular aneurysm repair (EVAR) of the aorta may trigger an inflammatory response that affects coagulation. In the EVAR of para-renal and thoraco-abdominal aortic aneurysms, the implants are more complex and the duration of surgery is longer. However, the exact pathophysiological mechanisms of coagulation activation are not yet well understood. The primary aim of this study is to investigate the effects of complex EVAR of para-renal and thoraco-abdominal aortic aneurysms on the coagulation status of patients. Methods: This prospective observational study (STROBE), approved and registered by the Ethics Committee of the University Hospital of Larissa (UHL) (NCT06432387), will enroll consecutive patients undergoing elective EVAR of para-renal and thoraco-abdominal aortic aneurysms. Exclusion criteria: Refusal to participate, previous surgery within 3 months, American Society of Anesthesiologists physical status (ASA PS) > 3, known history of thrombophilia or functional platelet dysfunction. Perioperative laboratory tests will be performed according to institutional guidelines. These include a complete blood count, conventional coagulation tests, and kidney and liver function tests. In addition, the following parameters will be determined: von Willebrand factor, factors VIII and XI, D-dimers, fibrinogen, Adamts-13, anti-Xa, platelet activation (multiplate), and high-sensitivity troponin. Blood samples will be taken pre-operatively before induction of anesthesia (01), on postoperative day 1 (02), and on postoperative day 3–4 (03). During hospitalization, myocardial injury after non-cardiac surgery (MINS), major adverse cardiovascular events after non-cardiac surgery (MACE), acute kidney injury (AKI), post-implantation syndrome (PIS), and death from any cause will be recorded. In addition, our patients will be reviewed at 30 days, 3, 6, and 12 months for MACE, implant failure, or death from any cause. All enrolled patients will be treated by the same medical team at UHL according to the indications. According to our power analysis, for a cohort of patients with three consecutive measurements, 58 patients should be included in the study. To compensate for possible dropouts, the sample size was increased to 65 patients. Conclusions: The results of the present study could help physicians to better understand the effects of complex EVAR of para-renal and thoraco-abdominal aortic aneurysms on blood coagulation and platelet activation.