SIR has released two new position statements on the best use of endovascular management for patients with iliofemoral deep vein thrombosis and chronic iliofemoral venous occlusion.
The statements, which are available online at sirweb.org and were published in the Journal of Vascular and Interventional Radiology provide recommendations for the management of DVT patients backed by comprehensive literature reviews and guidance from experts.
Suresh Vedantham, MD, FSIR, lead author, and Minhaj S. Khaja, MD, MBA, FSIR, recently spoke on these new position statements, particularly the management of chronic iliofemoral venous obstruction with endovascular placement of metallic stents.
Minhaj S. Khaja, MD, MBA, FSIR: Congratulations—you must be thrilled to see this project come to fruition!
Suresh Vedantham, MD, FSIR: Absolutely. The work group for this project (and for the acute DVT position statement SIR developed last year) included outstanding physician experts from IR, vascular medicine and vascular surgery, and we had excellent support from SIR staff. They worked very hard to distill many published studies and applied their patient care experience to arrive at what we hope are sensible recommendations.
MK: In several places, the position statement refers to standard venous disease assessment tools that are frequently employed in clinical studies, but there is potential for providers to utilize them for clinical care purposes as well. How would you advocate for the adoption of these tools?
SV: Venous disease exhibits diversity in its disease manifestations and clinical severity. At clinic visits, recall bias can affect patients and physicians. For these reasons, Recommendation #2 encourages providers to use these tools to complement their observations. A simple approach may be to choose one tool and apply it consistently. The Villalta Scale and the Venous Clinical Severity Scale (VCSS) are reasonable choices and can add objectivity to the process of selecting patients for intervention. For example, in the acute iliofemoral DVT subgroup of the ATTRACT trial, patients who presented with a Villalta score >10 experienced greater clinical benefit at 24 months from catheter-directed therapy than patients with lower severity scores.
MK: The NIVL (non-thrombotic iliac vein lesion) population is a subject of significant discourse. Could you elucidate your approach to managing these patients and how you incorporate the position statement into your practice?
SV: NIVLs can be challenging to identify, and given their diverse morphology, it can be difficult to estimate the impact of a given “lesion” on venous flow and patient symptoms. This problem is noted under Recommendation #5 of the venous obstruction statement, and a higher threshold is proposed for stent placement in NIVLs. My first principle is that if a patient does not have severe clinical manifestations, I refrain from imaging the iliac vein—that way, I am not tempted to intervene without need. Before imaging, I consider other possible causes of their symptoms, including venous valvular reflux and non-venous causes. Finally, I don’t start from a position that any lesion identified automatically accounts for the patient’s symptoms. Physicians are encouraged to read the section entitled, “Postthrombotic versus Nonthrombotic Lesions” to understand NIVL-specific issues and pitfalls and avoid poorly justified or non-secure stent placements.
MK: Appropriate stent sizing is paramount, particularly considering discussions surrounding stent migration, especially in the context of the NIVL population as highlighted in the position statement. Some operators may express apprehension about extending stents caudally to achieve a better seal. What guidance or reassurance would you offer to address their concerns?
SV: It’s important to consider each patient individually since venous geometry and lesion size and morphology can vary substantially among patients. As noted under Recommendation #12, caudal stent extension is one potential strategy to enable more secure stent affixation, but is not always necessary. Careful attention to accurately measuring the vein, over-sizing more for shorter and less fibrotic lesions and reverse taper in the native vein and positioning the stent properly (minimizing the length of stent that is in normal vein above the lesion) are also helpful. As noted in Recommendation #6, intravascular ultrasound (IVUS) is very helpful in evaluating the disease extent, properly sizing stents and then evaluating stent apposition and expansion.
MK: Follow-up is pivotal for patients suffering from postthrombotic syndrome. Could you share your insights on establishing clinical and imaging follow-up standards for such patients?
SV: Diligent follow-up can ensure optimal care for individual patients and can help identify unexpected events that may affect the broader community of stent candidates/recipients. Follow-up should focus particularly on compliance with anti-thrombotic therapy and evaluation for re-thrombosis. An early visit (within weeks) followed by visits at 1, 6 and 12 months, then yearly if the patient is doing well, may be reasonable for many patients. In our practice, we perform Duplex ultrasound on patients with residual or recurrent symptoms to evaluate the stents, inflow veins and valvular function. We apply a low threshold to perform venography with IVUS for patients with symptoms. We do not routinely use ultrasound surveillance in asymptomatic patients since we are not likely to re-intervene. All that said, this is clearly an area that could benefit from additional research to validate the best practices.
MK: The significance of inflow, particularly in patients with PTS, has been underscored. How would you recommend the evaluation of venous inflow? And which diagnostic modalities, such as ultrasound or venography, do you suggest?
SV: I think it is valuable for the IR provider to take a hands-on approach to using ultrasound in clinic to carefully evaluate the common femoral vein and its major tributaries. For stents to have a reasonable chance of long-term patency, the common femoral vein should have a robust flow channel (native or stented) and the upper segments of a femoral or deep femoral vein should be large and patent. Recommendation #5 discourages stent placement absent adequate inflow.
MK: The C-TRACT study stands as the singular rigorous investigation poised to address questions surrounding the efficacy of stenting for chronic iliofemoral obstruction. The position statement advocates for the referral of eligible patients to participating centers. Could you elaborate on strategies for facilitating such referrals within the healthcare system?
SV: Building a strong relationship with a hematologist or vascular internist is the best recipe for success in attracting patients with PTS to an IR. This can enable patients to benefit from a provider who understands PTS (many don’t) and also facilitate clinical trial enrollment. The use of database-driven searches from ultrasound laboratory or electronic health record resources can also be helpful, with appropriate IRB approvals and HIPAA waivers. As a researcher, I greatly appreciate SIR’s Recommendation #7, which endorses C-TRACT and other rigorous studies.
MK: Regarding antithrombotic therapy, do you have any specific inquiries or considerations you would like to raise for discussion?
SV: As the position statement highlights, it is important to conduct a serious assessment of the individualized bleeding risk of each patient to inform decisions. It is pretty clear that for patients with a history of DVT, stent patency will be a serious ongoing challenge and that a more aggressive stance towards anti-thrombotic therapy may be optimal for many patients. But more research is needed here and I would love to hear from you what you see being done to address this.
MK: The diversity in post-procedural therapeutic approaches arises from limited prospective randomized data and an incomplete grasp of the mechanisms influencing patency. Ongoing research efforts should prioritize the characterization of biological processes contributing to in-stent stenosis and re-thrombosis, exploration of the role of inflammation and anti-inflammatory treatments and execution of clinical studies that compare antithrombotic strategies stratified by patient type and intervention. Many of us in the venous world are looking at different parts of the puzzle and are thankful for pioneers like you having paved the way!
SV: It is really inspiring to see you and others in the “next generation” of venous IRs working hard to generate new evidence that can lead to better care for our patients. Thanks for your incredible dedication to this field!
