Secondary interventions after iliac vein stenting for chronic proximal venous outflow obstruction

Iliac vein stent placement is an increasingly common procedure in the treatment of chronic proximal venous outflow obstruction (PVOO), but secondary interventions after vein stent placement remain poorly characterized. Our goal was to identify the incidence, indications, operative findings, and outcomes of secondary interventions after the primary iliac vein stent procedure at a single institution. We retrospectively reviewed the clinical history of 490 patients (57.6% female, 42.4% male; mean age, 60.77 years [range, 18-92 years]; 93.28% follow-up, with a mean follow-up of 308.59 days) who underwent iliac vein stent placement for PVOO between October 2013 and January 2016. We evaluated the clinical presentation, intraoperative findings, and outcomes of those patients requiring a secondary intervention after an initial iliac vein stent procedure. Secondary interventions after an initial stent placement were identified in 50 of 490 patients (10.2%; mean age, 61.54 years [range, 19-92 years]; 58% female [n = 29]). At the time of each individual intervention, 1, 18, 17, 1, and 13 patients had Clinical, Etiology, Anatomy, and Pathophysiology class 2, 3, 4, 5, and 6 disease, respectively. Of these 50 patients, 58% (n = 29) of secondary interventions were due to recurrence of symptoms after the initial stent surgery, 18% (n = 9) were due to the development of new symptoms, and 24% (n = 12) were due to persistence of symptoms. The primary cause of PVOO in the patient cohort was 52% (n = 26) extrinsic iliac vein compression, 28% post-thrombotic, and 20% mixed. Intraoperative findings during the secondary intervention included malposition or angulation of the stent (6% [n = 3]); acute deep venous thrombosis/thrombosis (14% [n = 7]); an additional lesion, that is, stenosis in a native iliac vein proximal or distal to the original lesion (68% [n = 34]); stenosis within the stent, that is, stent stenosis without finding of thrombus or isolated, focal intrastent thrombosis (38% [n = 19]); and impairment of flow of the contralateral vessel from the previously placed stent (6% [n = 3]). The types of secondary interventions included placement of a new stent (86% [n = 43]), isolated balloon angioplasty alone (10% [n = 5]), and catheter pharmacomechanical thrombectomy (14% [n = 7]). Symptomatic improvement was observed after the secondary intervention in 90% of patients (n = 45), whereas only 2% (n = 1) of patients experienced only a transient improvement, and 8% of patient