Impact of degree of stenosis in May-Thurner syndrome on iliac vein stenting

Objective: May-Thurner syndrome (MTS) patients with lifestyle-limiting symptoms undergo stenting of the iliac vein for relief of compressive disease. The impact of degree of stenosis on clinical symptoms and outcomes after stenting is unknown and examined in our study. Methods: Retrospective review of contemporaneously entered data of 202 patients who underwent stenting for MTS between 2005 and 2011 was performed. Classification into three groups based on luminal area obtained by intraoperative intravascular ultrasound interrogation of the involved femoroiliocaval segments was carried out. Normal luminal diameters and areas were defined as 12 mm and 125 mm(2), 14 mm and 150 mm(2), and 16 mm and 200 mm(2) in the common femoral, external iliac, and common iliac veins, respectively. Mild (<60%), moderate (60%-89%), and severe (>90%) compression groups were defined using the normal values noted previously and observed after stenting to evaluate outcomes. Kaplan-Meier analysis was done to assess primary, primary assisted, and secondary patencies. Visual analog scale for pain scores, grade of swelling, and Venous Clinical Severity Score (VCSS) before and after stenting at 6, 24, and 48 months were analyzed using paired t-test and Tukey test. Logistic regression was used to gauge the impact of multiple variables including degree of stenosis on stent reintervention. Results: There were 55 patients who had mild, 87 patients who had moderate, and 60 patients who had severe iliac vein compression. Baseline demographic characteristics and comorbidities were similar across all groups. In addition, there was no statistically significant difference in median baseline visual analog scale score, grade of swelling, and VCSS among the groups. Compression was treated with angioplasty and stenting encompassing all areas of disease as determined by intravascular ultrasound. Stent technique involved use of Wallstent (Boston Scientific, Marlborough, Mass) only in 183 patients and Wallstent-Z stent (Cook Medical, Bloomington, Ind) combination in the remainder. No difference in median stent patency was noted on follow-up. Clinically, at 48 months, a statistically significant recurrence of pain, swelling, and worsening of VCSS were noted in the severe stenosis group but not in the other two groups. No variable was noted to have an impact on stent reintervention. Conclusions: Severity of MTS stenosis is not a predictor of initial clinical symptoms. Long term, patients with 90% initial MTS stenosis experience recurrence of symptoms. The degree of iliac venous stenosis does not appear to affect stent patency. Such information will help counsel patients before intervention.