New data indicate that venous stent failure “may be predicted by low peak flow velocity and post-thrombotic changes in inflow veins” and that endovascular venous stenting for chronic outflow obstructions is an “efficacious and safe” treatment in selected patients. These findings were recently published online ahead of print in the Journal of Vascular Surgery: Venous and Lymphatic Disorders (JVS-VL).
The authors of the study—Ulrike Hügel, MD, from Bern University Hospital, Bern, Switzerland) and colleagues—write that endovenous stent placement has become a first-line approach to prevent post-thrombotic syndrome in patients with chronic post-thrombotic obstruction (PTO) or non-thrombotic iliac vein lesions (NIVLs) if conservative management fails. “This study aims to identify factors associated with loss of patency to facilitate patient selection for endovenous stenting,” Hügel et al state.
The investigators retrospectively analyzed 108 consecutive patients following successful endovenous stenting for chronic vein obstruction performed at a single institution from January 2008 to July 2020. They explain their methods in the JVS-VL paper: “Using multivariable logistic regression, we explored potential predictive factors for loss of stent patency, including baseline demographics, post-thrombotic changes as well as peak flow velocities measured in the common femoral vein (CFV), deep femoral vein (DFV) and femoral vein (FV) using duplex ultrasound.”
Hügel and colleagues detail that the mean follow-up duration was 41±26 months and that participants, 46.3% of whom were women, had a mean age of 47.4±15.4 years. They add that 90 (83.3%) patients had PTO and 18 (16.7%) had NIVLs. Loss of patency occurred in 20 (18.5%) patients who were all treated for PTO, the authors communicate, noting also that comorbidities, side of intervention and sex did not differ between patients with occluded and patent stents.
“Stent occlusion was more common with increasing number of stents implanted (p<0.001) and with distal stent extension into and beyond the CFV (p<0.001),” Hügel et al report in JVS-VL.
The authors also reveal that lower duplex ultrasound peak velocity in the CFV (odds ratio [OR] 7.52; 95% confidence interval [CI] 2.54–22.28; p<0.001) and FV (OR 10.75; 95% CI 2.07–55.82; p<0.005) was a preinterventional predictive factor for stent occlusion. Post-thrombotic changes in the DFV (OR 4.51; 95% CI 1.53–13.25; p=0.006) and FV (OR 3.62; 95% CI 1.11–11.84; p=0.033), they add, was another predictive factor. Finally, the authors state that peak velocities of ≤7cm/s (interquartile range 0–20) in the CVF and ≤8cm/s (IQR 5–10) in the FV were “significantly associated with loss of patency”.
In the discussion of their findings, Hügel and colleagues claim that their study is the first to systematically explore predictors of venous stent occlusion that can be incorporated into the decision-making process prior to an intervention. They also acknowledge “several” limitations to their study, noting, for example, that the sample size was “moderate” and that the retrospective, single-center design and midterm follow-up duration limit the generalizability of the results.
“Insufficient venous inflow as assessed by low peak velocities in the CFV and FV as well as post-thrombotic findings represent reliable risk predictors for stent occlusion, warranting their inclusion into the decision-making process for invasive treatment of PTO,” the authors conclude.