IVUS Improves Management of Iliofemoral Venous Stenting
LAS VEGAS, NV—Intravascular ultrasound is more effective than venography at identifying iliofemoral venous lesions, evaluating their severity, and determining the best stent size to use in revascularization, according to a small feasibility study presented here at VIVA 2016.
According to Stephen Black, MD (St Thomas' Hospital, London, England), standard venography may not always be the most accurate method for calculating diameter stenosis of the target vessel when it comes to venous obstructions.
“By using IVUS, we find we are more readily able to identify the maximum area of stenosis,” Black said in a press conference prior to his presentation. He added that IVUS is “far more sensitive in detecting problems with a stent postimplantation, particularly when there may be residual depression of the stent requiring post implant dilatation or . . . any other technical issues of stent placement.”
Missed Moderate Residual Stenosis
The VIRTUS US iliofemoral stenting IDE trial, which Black presented in a late-breaking session on Monday, found a high degree of correlation between IVUS and venography. Minimum lumen diameter measurements were closely aligned between the two imaging techniques, with an average difference of 0.2 ± 1.7 mm. Furthermore, percent diameter stenosis measurements also were similar, with an average difference of 2.7 ± 12.8%.
Mean degree of stent oversizing was greater with venography compared with IVUS (18.1 ± 22.9% vs 12.5 ± 16.6%), driven by underestimation of reference vessel diameter. Most important, said Black, was the low correlation between venography and IVUS for residual percent stenosis following stent implantation. In several instances moderate residual intrastent stenosis were missed by venography, he noted.
The main trial enrolled 200 patients with clinically significant chronic, nonmalignant obstruction of the iliofemoral venous segment. Black reported results in the first 30 patients, who made up the feasibility study. The majority of patients (80%) were women who were postthrombotic with a previous DVT and an average age of 44.5 years.
Black stressed that while venography is important for guiding appropriate stent deployment, IVUS may offer more accuracy in assessing the severity of lesions and in properly sizing venous stents, which is important to prevent stent migration.
In the press conference prior to his presentation, Michael R. Jaff, DO (Massachusetts General Hospital, Boston, MA), asked Black what tips he had for operators to optimize their IVUS imaging in a central vein, where the landscape is different from an artery.
“I like to pause the IVUS at certain points to see if you get normal variations in size of the vessel,” he observed, adding that interpretation improves with practice.
Another major advantage for IVUS in this setting, he added, is the reduction in radiation with IVUS.
Following Black’s presentation, panelist Finn Donaldson, PhD, a premarket reviewer of medical devices for the US Food and Drug Administration (Silver Spring, MD), noted that given the lack of any approved stent in the US for iliac venous use, data of this type may be useful in moving toward a suitable device.
Panelist John A. Kaufman, MD (Dotter Interventional Institute, Portland, OR), added that another important issue is “trying to understand what is real and what isn’t real” in patients with iliofemoral compression, and understanding “who is symptomatic and who isn’t.” Also important in considering how to manage these patients, he added, is their young age and longer life expectancy compared with stenting for atherosclerosis in older patients. “You’ve got a long time for that metal to be in there, so you [want to be] really sure you need it,” he concluded.
Black S. VIRTUS US iliofemoral stenting IDE trial. Presented at: VIVA 2016. Las Vegas, NV. September 19, 2016.
- Black reports receiving honoraria from and consulting for Cook Medical, Medtronic, Optimed, Veniti and Volcano.