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 (CLI), acute limb ischemia (ALI), rupture, thromboembolic event (TE), or amputation.

Results: A total of 131 PAAs in 114 participants that underwent initial medical management were followed pre-operatively over a median period of 7.4 months (IQR 3.4, 12.7), had a mean age of 75 (IQR 70, 83) years old at diagnosis, and were majority white (98%; n=124) and male (98%; n=129). Multivariable models including age, race, sex, and aspirin status showed largest diameter (OR 1.01; 95% CI 1.00-1.01; p=0.044) and higher percent thrombus (OR 4.25; 95% CI 1.22-14.82; p=0.023) were associated with increased adverse events. A diameter threshold of 17.7 mm showed low sensitivity (44.4%), high specificity (91.2%), PPV of 94.1%, and NPV of 34.1%. A percent thrombus threshold of 59% yielded a sensitivity of 72.7%, specificity of 54.2%, PPV of 80.6%, and NPV of 43.2%.

Conclusion: 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.