Impact of native iliac vein aspect ratio on initial clinical presentation and outcomes following stenting for symptomatic chronic iliofemoral venous obstruction

Objective

Venous stenting has become the first line of treatment for patients with symptomatic chronic iliofemoral venous obstruction (CIVO) in whom conservative therapy has failed. Intravascular ultrasound (IVUS) interrogation with the use of normal minimal luminal diameters or areas has become the standard to confirm the diagnosis and determine the adequacy of stenting. However, the aspect ratio (ratio between the maximal and minimal luminal diameters) has also been put forth as a possible metric for determining stent adequacy. This study explores the utility of the native iliac vein and stent aspect ratios in determining the initial presentation and outcomes after stenting.

Methods

A retrospective analysis of contemporaneously entered data from patients who underwent stenting for quality of life (QoL)-impairing clinical manifestations of CIVO for whom conservative therapy had failed formed the study cohort. The limbs were grouped into three at the time of intervention using the IVUS-determined native vein aspect ratio: group I, those with a ratio of ≤1.4; group II, those with a ratio of 1.41 to 1.99; and group III, those with a ratio of ≥2. The characteristics appraised initially and after stenting included the venous clinical severity score, grade of swelling (GOS), visual analog scale (VAS) for pain score, and the CIVIQ-20 QoL score. Analysis of variance and paired and unpaired t tests were used for comparison of clinical and QoL variables, and Kaplan-Meier analysis was used to evaluate stent patency, with the log-rank test used to discriminate between different curves.

Results

There were a total of 236 limbs (236 patients). The median age for the entire cohort was 62 years (range, 16-92 years). There were 161 women in the study, and left laterality was more common (137 limbs). Post-thrombotic obstruction was noted in 201 limbs (86%). The median body mass index was 36 kg/m². There were 54 (23%), 64 (27%), and 118 (50%) limbs in groups I, II, and III, respectively. The median follow-up was 65 months. For the entire cohort, after stenting, the venous clinical severity score improved from 6 to 4 (P < .0001) at 3 months and remained at 4 at 6 months (P < .0001), 12 months (P < .0001), and 24 months (P < .0001). The GOS for the entire cohort improved from 3 to 1 (P < .0001) at 3 months and remained at 1 at 6 months (P < .0001), 12 months (P < .0001), and 24 months (P < .0001). The VAS for pain score for the entire cohort improved from 7 to 0 (P < .0001) at 3 months, increased to 2 (P < .0001) at 6 months, and remained at 2 (P < .0001) at 12 months. At 24 months, the VAS for pain score worsened to 3 (P < .0001). For the entire cohort, the CIVIQ-20 score improved from 62 to 40 (P < .0001). There was no difference in the GOS, VAS for pain score, or CIVIQ-20 score between the groups at baseline or at 6, 12, and 24 months after intervention. At 60 months, the primary stent patency was 89% for group I, 80% for group II, and 75% for group III (P = .85). The primary assisted stent patency was 100% for group I, 98% for group II, and 98% for group III (P = .5). Secondary patency was 100% for groups II and III (P > .5). Reintervention was pursued for QoL-impairing clinical manifestations in 53 limbs (22%) without a significant difference between the three groups (P = .13).

Conclusions

The native vein aspect ratio does not appear to determine the initial clinical presentation or QoL or impact the clinical or QoL outcomes after stenting for CIVO. Following stenting, no patient had an aspect ratio >2, with 97% of patients having an aspect ratio ≤1.4 and the remaining 3% having an aspect ratio of 1.41 to 1.99. IVUS-determined minimal cross-sectional luminal area and not the aspect ratios should be used for confirmation of the diagnosis of CIVO and to assess the adequacy of stenting.