Lessons Learned From Reinterventions After Vein Stent Placements

Abstract

The goal of this study is to understand why venous iliocaval stents fail. We retrospectively reviewed 994 patients who underwent stenting for chronic iliocaval obstruction between January 9, 2013, and June 26, 2019, at a single institution. Females comprised 56.5% (n = 562) and mean age was 60 years (range, 19–95). Time from the first vein stenting procedure to the last visit ranged from 0 to 2368 days (mean, 529 days). Follow-up at 30 days was 91.4% and at 1 year or greater was 48.7%. The patients who needed reintervention were stratified based on intraoperative findings and symptom resolution. Within this venous stent population, 166 major reinterventions (all endovascular) were performed. Females comprised 56% (n = 93). Mean age was 62 ± 13 years (range, 19-91 years). Mean time from the first operation to the reintervention was 778 ± 532 days (range, 7-2737 days), and mean time to the last follow-up was 1375 ± 611 days (range, 42-3017 days). Major intraoperative findings during reinterventions included: stenosis in native vein proximal or distal to prior stent in 45% (n = 74), stent-related complications (stent stenosis, angulation, malposition) in 28% (n = 46), outflow obstruction from contralateral stent in 21% (n = 35), stenosis in contralateral native vein in 18% (n = 30), no major finding in 14% (n = 24), acute stent thrombosis in 5% (n = 8), and chronic stent thrombosis in 2% (n = 4). Interventions performed included stent(s) placement in 47% (n = 78), delayed iliac kissing stents in 22% (n = 37), no intervention 1 in 5% (n = 25), balloon angioplasty alone in 14% (n = 24), and catheter thrombolysis in 4% (n = 7). At 6 months after the reinterventions, outcomes were graded as worse than preoperatively in <1% (n = 1), no change in 9% (n = 15), minor improvement in 13% (n = 21), major improvement in 35% (n = 59), symptom resolution in 29% (n = 49), and no information in 14% (n = 23). The majority of vein stent failures were related to a technical aspect of the initial stenting procedure. There was no intrinsic biological process or stent structural issue that alone resulted in stent failure. Intimal hyperplasia was not observed in venous stents. Acute and chronic stent thrombosis were uncommon; review of each case demonstrated an underlying mechanical cause of the stent thrombosis in every case. The most common finding during reinterventions was a new or previously missed stenosis in a native iliac vein. Other common findings were related to technical failures such as inadequate stent expansion or malposition of the initial stent(s). Unilateral stents that extended into the inferior vena cava obstructed flow from the contralateral iliac vein over time in a small number of cases. Reinterventions identified distinct problems that could be corrected and mostly resulted in symptomatic improvement for the patient.