research forum By Kush R. Desai, MD, FSIR The future of deep venous care


Iliac-obstructive post-thrombotic syndrome and the C-TRACT Trial


P


ost-thrombotic syndrome (PTS) is a chronic condition that develops in nearly half of all patients following proximal lower


extremity deep vein thrombosis (DVT).1,2 Many patients have mild to moderate symptoms, manifested by a variable combination of edema, pain/heaviness, fatigue and paresthesia that can be managed effectively with conservative measures, including compression, rest and elevation. However, approximately half of all PTS patients go on to develop moderate to severe symptoms reflective of iliac vein stenosis or occlusion.3


In


these patients, PTS is characterized by a spectrum of debilitating symptoms including venous claudication that limits normal walking activities due to a “bursting” pain, severe edema that is restrictive to movement and is less responsive to compression therapy, and venous stasis ulceration, which can cause infections and may necessitate operative debridement.4,5


These symptoms can


profoundly affect quality of life (QOL); patients with severe PTS have reported the impact to their QOL to be comparable to patients with angina, cancer and congestive heart failure.6,7


Conservative management of iliac- obstructive PTS is centered around anticoagulation, compression therapy and, when necessary, wound care. However,


the efficacy of each of these therapies is limited overall. While anticoagulation may prevent progression and recurrence of DVT, PTS often develops nonetheless.1,2 Further, the results of a large, multicenter randomized trial demonstrate that elastic compression does not lower PTS incidence,8


with other studies


demonstrating limited evidence of efficacy in symptom reduction in patients suffering from severe PTS.9


Finally, once a venous


ulcer develops, patients find themselves with symptoms that wax and wane, requiring frequent wound care when an active ulcer is present. Thus, patients with iliac-obstructive PTS find themselves with a paucity of effective, durable therapies.


Ambulatory venous hypertension is the final common pathway in iliac- obstructive PTS, resulting from a combination of venous obstruction and reflux.4,10


While some of the changes of


chronic deep venous obstructive disease are irreversible, iliac vein obstruction and saphenous reflux can be corrected with endovascular therapy and are frequently treated by interventional radiologists. Iliac vein stents have long been placed for treatment of chronic iliac vein stenosis or occlusion, with several studies demonstrating efficacy in reduction of symptoms of iliac-obstructive PTS. The largest study examined 464 patients with post-thrombotic obstruction


and noted significant reductions in swelling and pain, as well as ulcer healing in nearly 70% of patients.11


Iliac


vein stent placement has also been shown to improve symptoms of venous claudication and calf pump dysfunction.12 Similarly, endovenous ablation for saphenous reflux has long been performed by interventional radiologists, and two studies have demonstrated the potential value of treating saphenous reflux following iliac stent placement in patients with iliac-obstructive PTS, with a nearly 70% ulcer healing rate.13,14


However, there is equipoise regarding the durability of endovascular therapy in the treatment of iliac-obstructive PTS, particularly iliac vein stent placement. A meta-analysis of 37 studies found a combined 79% 1-year primary patency of iliac vein stents placed in post-thrombotic obstructions, with a projected primary patency of 60% at 5 years.15


This issue is


particularly vexing, as PTS affects a wide cross section of society. Unlike other vascular diseases that typically afflict an older population, younger patients are frequently affected by PTS, and concerns over stent patency become a matter of decades, not years. In such patients, if frequent procedures are required to maintain patency, this may place an undue burden on patients with high associated cost. Further, most endovascular therapy studies are retrospective, unblinded and of a modest sample size with limited follow-up, underscoring the significant risk for a bias and potential overstatement of procedural efficacy.


Photo provided by Kush R. Desai, MD, FSIR 22 IRQ | SUMMER 2020


These concerns are reflected in an overall lack of confidence that regulators have in endovascular PTS therapy. In a 2016 Medicare Evidence Development and Coverage Advisory Committee Meeting, the convened panel noted a “very low” level of confidence that any intervention improved health care outcomes in patients with iliac-obstructive PTS; they further


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