Effect of stent shape in areas of high compression on patency rates after venous recanalization in patients with chronic venous obstruction.

Abstract

Background: Venous stenting of the obstructed iliofemoral veins has gained significant popularity over recent years due to its efficacy in restoring venous flow and alleviating symptoms associated with chronic venous obstruction (CVO). The success of venous stenting has been demonstrated through high patency rates, even in cases where stents are implanted in areas of high compression. These stents have been observed to adopt an elliptical shape at areas of high compression, deviating from the expected circular morphology that stents are designed to maintain. This phenomenon raises important questions about its potential impact on stent function and long-term patency rates. The objective of this study was to investigate, through a retrospective analysis, the presence and clinical impact of non-circular-shaped venous stents on patency rates.

Methods: From December 2015 to December 2020, a cohort of 115 patients (127 limbs) diagnosed with chronic obstruction of the iliofemoral veins underwent venous angioplasty with stent implantation. Throughout follow-up visits, detailed data were collected, including patient demographics, characteristics, stent types, and ultrasound findings, while especially focusing on the shape and diameter of stents at areas of known external compression, such as the May-Thurner point and under the inguinal ligament.

Results: The average follow-up duration was 21.9±8.7 months. The primary patency rate was 79.5%, with an assisted primary patency rate of 92.1% and a secondary patency rate of 96.7%. All the stents implanted were dedicated venous stents, which demonstrated favorable outcomes overall. However, during the follow-up period, 76.56% of the stents were found to have adopted an elliptical shape at areas of high external compression, regardless of the type or structure of the stent. Interestingly, neither the change in stent shape nor a reduction in stent area of less than 25% showed any statistically significant impact on the overall patency rates.

Conclusions: This study demonstrates that changes in stent shape are to be expected at points of high external pressure. However, as long as these changes do not lead to a severe reduction in stent lumen (<25% of stent area), they do not negatively impact patency rates.