VESS07 - Analysis of risk factors for acute limb ischemia in popliteal artery aneurysms (JAST2302 study)

Objectives: Acute limb ischemia (ALI) is a critical complication of popliteal artery aneurysms (PAAs), and its prevention is a primary goal of treatment. Current SVS guidelines recommend intervention for asymptomatic PAAs ≥20mm to reduce the risk of thromboembolisms. However, clinical observations indicate that PAAs < 20mm can also present with ALI, suggesting a potential risk of ALI regardless of PAA size. The factors contributing to ALI in PAA patients remain insufficiently understood. This study aimed to identify risk factors for patients with PAAs.

Methods: A retrospective analysis was conducted on PAA cases treated between 2005 and 2024 across eight institutions in Japan. Data were analyzed to assess the incidence of ALI and associated risk factors using univariate and multivariate analyses. Risk factors evaluated included patient background characteristics and anatomical factors, such as thrombus volume, irregular thrombus contours, and PAA length, assessed via preoperative computed tomography angiography.

Results: A total of 150 PAAs were included in the analysis. The overall incidence of ALI was 23% (35 cases). ALI incidence based on PAA diameter was 28.6% (n=10) for 10-19mm, 31.4% (n=11) for 20-29mm, 20.0% (n=7) for 30-39mm, and 17.1% (n=6) for 40-49mm.
Univariate analysis identified preoperative claudication (odds ratio[OR], 2.36; 95% confidence interval [CI], 1.07-5.19; P=.043) as the sole significant patient-related risk factor, while atrial fibrillation was not associated with ALI. Anatomical factors significantly associated with ALI included thrombus area ≥75% of the PAA area (OR, 11.5; 95%CI, 4.19–40.5; P < .0001) and the presence of irregular thrombus contours (OR, 3.6; 95%CI, 1.63–7.84; P=.0015). Irregular thrombus contours were defined as thrombus surfaces that are not smooth but exhibit uneven or irregular shapes, indicating a more complex morphology.　PAA length was not significant. Multivariate analysis demonstrated that irregular thrombus contours (OR, 2.43; 95%CI, 1.01–5.86; P=.047) and thrombus area ≥75% (OR, 30.0; 95%CI, 3.81–236.2; P=.0012) were significant predictors of ALI, while maximum PAA diameter was not.

Conclusions: A large thrombus area observed on a single cross-sectional image indicates a higher risk of ALI, regardless of PAA diameter. Additionally, irregular thrombus contours further increase ALI risk, highlighting the need to consider active treatment in such cases. These findings suggest the potential need to reconsider treatment strategies even for small-diameter PAAs when these risk factors are present.