Percent Thrombus Outperforms Size in Predicting Popliteal Artery Aneurysm Related Thromboembolic Events

Abstract

ABSTRACTIntroductionPopliteal artery aneurysms (PAAs) are associated with high morbidity and mortality and current Society for Vascular Surgery (SVS) recommend operative repair for PAAs with a diameter greater than 20 mm, which is based on limited evidence. To help risk stratify patients for surgery, our aim was to identify anatomic characteristics of PAA associated with limb threatening and thromboembolic events (TEs).MethodsA retrospective multi-institutional cohort was queried for all patients with a PAA from 2008 to 2022. Symptom status at the time of presentation was divided into three categories: symptomatic PAA with documented claudication or chronic limb ischemia (CLI), limb threatening PAA with a TE, acute limb ischemia, or rupture, and asymptomatic PAA without symptoms or limb threatening events. Patient and anatomic factors based on duplex ultrasound (DUS) were evaluated as potential predictors of symptom groups and thresholds of anatomic variables were identified using receiver operating characteristic curves.ResultsThere were 470 PAAs identified in 331 patients. The mean age was 74 years at diagnosis, 94% of patients were white, and 97% of patients were male. Cardiovascular comorbidities were prevalent in and similar between all patient groups studied, and almost all patients were on anticoagulation or antiplatelet therapy at the time of diagnosis, at 96%. The most common concurrent aneurysm was abdominal aortic aneurysm (62%). Patient comorbidities were not associated with symptom status. PAAs with a higher percent thrombus burden were 18 times more likely to experience a limb threatening event and 24 times more likely to experience a TE. A largest diameter threshold of 20.4 mm was predictive of a TE (sensitivity 78.1%, specificity 40.5%), but percent thrombus threshold of 62% outperformed largest diameter as a predictor of a TE (sensitivity of 81.3%, specificity 52.0%). Percent thrombus threshold of 73% also predicted limb threatening events (sensitivity 65.7%, specificity 69.7%).ConclusionA PAA diameter greater than 20.4 mm was predictive of TEs, which is in agreement with clinical practice guidelines. However, percent thrombus greater than 62% outperformed largest diameter as a predictor of a TE. This analysis supports the use of size greater than 20.4 mm and 62% thrombus in identifying high risk PAAs that warrant repair.