Determining patient risk factors associated with accelerated growth of popliteal artery aneurysms

The objective of this study was to determine the natural progression of popliteal artery aneurysms (PAAs) and clinical variables associated with their accelerated growth.

Retrospective chart review of 224 patients with encounters between January 2008 and May 2016 and with at least one PAA was conducted. From this group, 65 asymptomatic patients had either unilateral (n = 43) or bilateral (n = 22) PAAs that were observed for at least 1 year of medical management before intervention. We divided these aneurysms into two groups based on whether their overall growth rate was above or below the eventual mean. Aneurysm diameter was taken from duplex ultrasound and computed tomography angiography.

There were 87 aneurysms evaluated among 65 patients. Mean age at diagnosis was 70.9 years (standard deviation [SD], 9.39 years), and 64 patients were male (98%); 50 (77%) were white and 7 (11%) were African American. The average body mass index was 27.69 (SD, 4.90). At or before initial diagnosis, 61 (94%) patients had a concomitant lower extremity or abdominal aortic aneurysm; 51 (78%) patients were current or former smokers; and 16 (25%) had atrial fibrillation. The average growth rate of all aneurysms was 1.22 mm/y (SD, 1.93 mm). The mean surveillance time from initial diagnosis to last follow-up or intervention was 3.12 years (SD, 1.66 years). Of 87 aneurysms, 25 (29%) were repaired; 18 (21%) were repaired because of size criteria, 2 (2%) because of symptom criteria (claudication or acute limb ischemia), and 5 (6%) because of both criteria. During our study window, 62 aneurysms (71%) remained asymptomatic or did not undergo an intervention. The mean initial diameter at diagnosis was 16.9 mm (SD, 5.32 mm). Within the study, 50 (57%) aneurysms presented with or developed mural thrombus. Univariate analysis identified larger initial diameter (19.2 vs 14.7 mm; P = .020), atrial fibrillation (35% vs 16%; P = .042), and mural thrombus (38% vs 20%; P < .001) as predictors of diameter expansion greater than the mean. Multivariable analysis of the significant univariate factors determined that only initial diameter (odds ratio, 5.53; P = .007) and the presence or development of mural thrombus (odds ratio, 4.00; P = .008) maintained significance.

Patients presenting with a PAA at 20 mm or >20 mm in diameter, presence of luminal thrombus, or atrial fibrillation may need to be observed at more frequent scanning intervals than those without these risk factors. Further studies are required to validate these predictive growth factors.