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

ObjectiveVenous stenting has become the first line of treatment for patients with symptomatic chronic iliofemoral venous obstruction (CIVO) who have failed conservative therapy. Intravascular ultrasound (IVUS) interrogation with use of normal minimal luminal diameters or areas has become the standard to confirm diagnosis as well as determine adequacy of stenting. However, aspect ratio (ratio between the maximal and minimal luminal diameters) has also been put forth as a possible metric for determining adequacy of stenting. This study explores the utility of the native iliac vein and stent aspect ratios in determining initial presentation and outcomes post stenting.MethodsA retrospective analysis of contemporaneously entered data on patients who underwent stenting for quality-of-life (QoL) impairing clinical manifestations of CIVO who had failed conservative therapy formed the study cohort. The limbs were grouped into 3 at the time of intervention using 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 with a ratio of >2. Characteristics appraised initially and post stenting included venous clinical severity score (VCSS), Grade of swelling (GOS), VAS pain score and the CIVIQ – 20 quality of life (QoL) score. ANOVA and paired/unpaired t- tests were used for comparison of clinical/QoL variables, while Kaplan - Meier analysis was used to evaluate stent patencies with log-rank test used to discriminate between different curves.ResultsThere 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 BMI was 36. There were 54 (23%), 64 (27%) and 118 (50%) limbs in groups I, II and III respectively. Median follow up was 65 months. For the entire cohort, post stenting, VCSS improved from 6 to 4 (p<0.0001) at 3 months and remained at 4 at 6 months (p<0.0001), 12 months (p<0.0001) and 24 months (p<0.0001). GOS for the entire cohort improved from 3 to 1 (p<0.0001) at 3 months and remained at 1 at 6 months (p<0.0001), 12 months (p<0.0001) and 24 months (p<0.0001). VAS pain score for the entire cohort the VCSS improved from 7 to 0 (p<0.0001) at 3 months, went up to 2 (p<0.0001) at 6 months and remained at 2 (p<0.0001) at 12 months. At 24 months the VAS pain score worsened to 3 (p<0.0001). For the entire cohort, the CIVIQ-20 score improved from 62 to 40 (p<0.0001). There was no difference in the GOS, VAS pain score or CIVIQ-20 score between the groups at baseline or at 6-, 12- and 24-months post intervention. At 60 Months, the primary stent patency was 89% for Group I, 80% for Group II and 75% for Group III (p =0.85); the primary assisted stent patency was 100% for Group I, 98% for Group II and 98% for Group III (p=0.5); secondary patency was 100% for Groups II and III (p>0.5). Reintervention was pursued for QoL impairing clinical manifestations in 53 (22%) limbs without a significant difference between the 3 groups (p=0.13).ConclusionsNative vein aspect ratio does not appear to determine initial clinical presentation/quality of life or impact clinical/quality of life outcomes post stenting in patients undergoing stenting for quality-of-life impairing symptoms of CIVO who have failed conservative therapy. Post-stenting there was an improvement in the aspect ratios (97% in Group I and 3% in Group 2) compared to the pre-stenting native vein aspect ratios (23% in Group I, 27% in Group II and 50% in Group III). IVUS determined minimal cross-sectional luminal area and not aspect ratios should be used for confirmation of the diagnosis of CIVO and assessing the adequacy of stenting.