Underexpansion of Wallstents ® in the Treatment of Nonthrombotic Iliac Vein Lesions.

BACKGROUND: Iliac vein stenting is increasingly being used in the treatment of chronic venous insufficiency for patients with nonthrombotic iliac vein lesions (NIVL). We have noticed that many stents do not deploy to the expected stent area (ESA) as designated by the manufactured stent diameter (MSD). The purpose of this study was to evaluate the dynamics of Wallstent® expansion in the iliocaval system.

METHODS: Retrospective analysis of all patients with NIVL who were treated with iliac vein stenting using Wallstents® was performed. None of the patients in this study underwent pre-or post-stenting balloon angioplasty. Multiway analysis of variance and multiple linear regression analyses were performed to examine the effects of gender, age, stent laterality, location of stenosis, and CEAP (clinical, etiology, anatomy, and pathophysiology) score at presentation on the proportion of observed stent area (OSA) to ESA.

RESULTS: Two-hundred three patients (64 male and 139 female; mean age: 68 ± 13.9 years) underwent 242 treatments between December 2012 and January 2016. Presenting symptoms based on CEAP score were: C1 (0), C2 (0), C3 (n = 59, 24%), C4 (n = 148, 61%), C5 (n = 4, 2%), and C6 (n = 31, 13%). On average, stents deployed to 69.58% of the ESA (range, 23.87-123.35%). Multiple linear regression analysis showed a significant negative correlation between increasing MSD and ESA achieved. Regression coefficients for differences in percent difference between ESA and OSA based on MSDs were as follows: 16 mm (-15.0, P = 0.1519), 18 mm (-21.0, P = 0.0077), 20 mm (-23.2, P = 0.0059), and 20-22 mm (-35.3, P < 0.0001). No significant difference in stent underexpansion was detected based on gender, age, stent laterality, location of stenosis, or CEAP score.

CONCLUSIONS: Larger MSD is associated with greater magnitude of stent underexpansion. These findings may have implications for future venous stent designing.