Percent Thrombus Predicts Popliteal Artery Aneurysm-Related Thromboembolic Events

Popliteal artery aneurysms (PAAs) are associated with high morbidity and mortality. Current guidelines recommend operative repair for PAAs with a diameter greater than 20 mm based on very limited evidence. The objective of this study was to identify clinical and anatomic characteristics of PAA associated with limb-threatening and thromboembolic events (TEs). This multi-institutional retrospective cohort was derived from the Massachusetts General Brigham Research Patient Data Registry. The registry was queried for all patients with a PAA from 2008 to 2022, and a chart review was performed for the presence of a PAA, defined as greater than 1 cm on any imaging modality. Duplex ultrasound characteristics of PAAs were abstracted by certified registered physicians in vascular interpretation. The primary outcome was symptom status, which was divided into three categories: symptomatic PAA with documented claudication or chronic limb ischemia, limb-threatening PAA with a TE, acute limb ischemia, or rupture, and asymptomatic PAA without symptoms or limb-threatening events. A total of 470 PAAs were identified in 331 patients. The mean age was 74 years at diagnosis; 94% of patients were White, and 97% 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 (96%). Patient comorbidities and medications were not associated with symptom status. Higher percent thrombus was significantly associated with PAA with a TE, PAAs with a limb-threatening event, and symptomatic PAAs in a multivariable model including age (Table). Channel area, thrombus area, largest diameter, and mural thrombus did not have any significant association with symptom status or limb-threatening events. A largest diameter threshold of 20.4 mm was predictive of a TE (sensitivity 78.1% and specificity 40.5%), but a percent thrombus threshold of 62% outperformed largest diameter as a predictor of a TE (sensitivity 81.3% and specificity 52.0%) (Fig). Percent thrombus was significantly associated with TEs, symptomatic PAAs, and limb-threatening events, whereas diameter was not significantly associated with any symptom group. Percent thrombus greater than 62% outperformed largest diameter as a predictor of a TE. This analysis supports the use of percent thrombus in identifying high-risk PAAs that warrant repair.TablePopliteal artery aneurysm (PAA) characteristics associated with symptomatic PAA, limb-threatening PAA, or PAA with a thromboembolic event in a multivariable model controlling for ageCharacteristicRRR95% CI lower95% CI upperP valuePercent thrombus, % Symptomatic15.22.6972.3<.01 Limb threatening17.93.7685.0<.01 TE24.31.44410.03Largest diameter, mm Symptomatic1.050.971.2.22 Limb threatening0.990.851.15.89 TE1.000.971.02.81Patent channel area, mm2 Symptomatic1.000.971.02.86 Limb threatening0.960.921.00.07 TE1.000.991.00.25Thrombus area, mm2 Symptomatic1.011.001.02.05 Limb threatening1.011.001.02.06 TE1.001.001.00.15CI, Confidence interval; RRR, XXX; TE, thromboembolic event.Boldface P values represent statistical significance. Open table in a new tab