Natural History of Popliteal Artery Aneurysm: Evaluating Percent Thrombus and Size Threshold for Operative Management

Abstract

Background: Popliteal artery aneurysms (PAAs), the most common peripheral arterial aneurysms, are associated with high rates of limb amputation and mortality. This study assessed the risk of adverse events associated with PAA anatomic characteristics and establish threshold values to guide surgical decision making.

Study design: A retrospective cross-sectional cohort was queried for all patients with a PAA from 2008 to 2022. Anatomic characteristics included largest diameter, defined as the maximum diameter measured in either the anterior posterior or transverse dimension, and percent thrombus, calculated by dividing the thrombus area by the total aneurysm area and multiplying by 100. A composite outcome, termed any adverse event, included critical limb ischemia, acute limb ischemia, rupture, thromboembolic event, or amputation.

Results: A total of 131 PAAs in 114 participants who underwent initial medical management were followed preoperatively for a median period of 7.4 months (interquartile range 3.4 to 12.7 months), had a mean age of 75 (interquartile range 70 to 83) years at diagnosis, and the majority were White (98%; 124) and men (98%; 129). Multivariable models including age, race, sex, and aspirin status showed largest diameter (odds ratio 1.01; 95% CI 1.00 to 1.01; p = 0.044) and higher percent thrombus (odds ratio 4.25; 95% CI 1.22 to 14.82; p = 0.023) were associated with increased adverse events. A diameter threshold of 17.7 mmol/L showed low sensitivity (44.4%), high specificity (91.2%), positive predictive value of 94.1%, and negative predictive value of 34.1%. A percent thrombus threshold of 59% yielded a sensitivity of 72.7%, specificity of 54.2%, positive predictive value of 80.6%, and negative predictive value of 43.2%.

Conclusions: These results suggest that size thresholds for PAA repair may warrant reconsideration. Percent thrombus burden may serve as additional criteria for identifying high-risk PAAs that warrant operative repair.