Abstract No. 504 Update: iliocaval-in-stent restenosis

Abstract

To examine patient, stent, and angioplasty factors associated with 50% and 75% in-stent restenosis (ISR) of iliocaval stents placed for chronic venous thrombosis with results at 1, 3, 5, and 20 years post-placement. All patients with symptomatic chronic iliocaval venous thrombosis who underwent iliocaval stent placement with either SMART (Cordis, Santa Clara, CA) or Wallstent (Boston Scientific, Natick MA) at an academic medical center from 1996 to 2018 were compiled from a departmental database. In total, 620 iliocaval stents (430 SMART, 190 Wallstent) were placed in 176 patients (52.8% male, median age 51.1 y). Median follow -was 538.1 days (range, 0–6473 days). Rates of ISR at > 50% and > 75% luminal obstruction were calculated using Kaplan-Meier methods. Cox regression analysis of the effects of age, gender, stent brand, stent diameter, stent length, and angioplasty balloon diameter, on ISR was performed. Median and mean time to ISR were 153.5 and 299.2 days, respectively (range, 3–3985 days). In the 20 year follow-up period, ISR occurred in 8.7% of inferior vena cava (IVC) stents, 10.9% of common iliac vein (CIV) stents, and 15.3% of external iliac vein (EIV) stents. Gender did not affect ISR. Increased age was associated with a small but significant increased risk of ISR when all veins were examined as a single cohort at 1, 3, 5, and 20 years and within the EIV at 3, 5, and 20 years. Wallstents were associated with decreased rate of ISR when all veins were examined as a single cohort at 1, 3, 5, and 20 years as well as within EIV and CIV at 1, 3, 5, and 20 years. A small but significant increased risk of ISR was noted with larger stents in the EIV at 1, 3, 5, and 20 years and IVC at 1 year only as well as when all veins are examined as a single cohort at 1, 3, 5, and 20 years. Smaller balloon diameter demonstrated an increased risk of ISR within IVC stents at 1 year only. When the threshold for ISR was raised to > 75% ISR, all of the above significant results were the same. However, in addition, increasing stent length was associated with a small but significant risk of ISR > 75% when all veins were examined as a single cohort at 1, 3, 5, and 20 years. Our study demonstrates clinically acceptable and decreased rates of ISR compared to prior studies for the IVC, CIV, and EIV stents. Age is a small but significant risk factor for ISR, especially within the EIV. Wallstents may decrease ISR in iliac veins but are similar to SMART stents when placed in the IVC. Larger balloon diameters may help with short-term IVC ISR and larger stents may increase the risk of ISR in the EIV.