Association Between Preoperative Ankle-Brachial Index and Postoperative Renal Adverse Events in Patients With Acute Stanford Type A Aortic Dissection: A Single-Center Retrospective Cohort Study

Acute Stanford type A aortic dissection is a life-threatening cardiovascular emergency that usually requires urgent surgical repair. Postoperative acute kidney injury is a common and clinically important complication after surgery for acute type A aortic dissection and is associated with worse short-term and long-term outcomes. Identification of preoperative vascular markers associated with postoperative renal adverse events may help improve perioperative risk stratification.

The ankle-brachial index is a simple, noninvasive measure calculated from systolic blood pressure measured at the ankle and arm. Although a low ankle-brachial index is commonly used to identify peripheral artery disease, an abnormally high ankle-brachial index, usually defined as 1.4 or higher, may reflect noncompressible arteries, medial arterial calcification, and increased arterial stiffness. These vascular abnormalities may be associated with impaired renal perfusion reserve and increased susceptibility to kidney injury after major cardiovascular surgery.

This is a single-center, retrospective observational cohort study. The study will include patients with acute Stanford type A aortic dissection who underwent surgical repair at Nanjing First Hospital, Nanjing Medical University, from January 2021 to February 2024. Clinical data will be obtained from existing medical records. No study-specific intervention, treatment allocation, or additional follow-up will be performed.

The main exposure is preoperative ankle-brachial index. Patients will be categorized according to whether they have a high ankle-brachial index, defined as an ankle-brachial index of 1.4 or higher. The primary outcome is postoperative acute kidney injury within 7 days after surgery. Renal outcomes will be assessed using routinely collected perioperative clinical and laboratory data.

The study will compare baseline characteristics, perioperative variables, and postoperative renal outcomes between patients with and without a high preoperative ankle-brachial index. Multivariable regression models will be used to evaluate the association between high ankle-brachial index and postoperative renal adverse events after adjustment for relevant clinical covariates. Additional analyses may assess the association between ankle-brachial index and the severity of postoperative renal injury, as well as the robustness of the findings in sensitivity analyses.