At the 2016 Leipzig Interventional Course meeting (LINC; 26–29 January, Leipzig, Germany), Michael R Jaff, Boston, USA, discussed the challenges facing intervention for deep vein thrombosis and pulmonary embolism, and when using an interventional approach may be preferable.
“When you think about the current management of deep vein thrombosis, whether you like it or not, most of your colleagues—particularly the non-interventionalists—believe that this begins and ends with medical therapy alone,” Jaff told the LINC audience.
“Many physicians believe that they are experts in the management of deep vein thrombosis,” Jaff continued. “Their perception is that patients do incredibly well with standard anticoagulation. Now, with novel oral anticoagulants, we do not even have to give patients injections.” Such technology allows physicians to keep patients out of the hospital altogether, so “why incur the risks and additional costs associated with intervention?” Jaff asked.
An interventionalist could answer this question, Jaff said, by looking at the goals of endovascular therapy for the treatment of deep vein thrombosis. As a result of more rapid lysis via local administration of the drug, endovascular therapy relieves acute pain and oedema and may prevent pulmonary embolism, recurrent thrombosis and post-thrombotic syndrome. Vessel patency can be restored, valve function preserved and underlying anatomical lesions corrected.
For certain indications, endovascular intervention is preferable, for example, in patients with extensive iliofemoral deep vein thrombosis or involvement of the inferior vena cava. In young, highly-functional patients, “if you leave the clot there they are at high risk of being left with debilitating venous insufficiency in their middle age or later,” Jaff suggested. This is also the case for patients with symptomatic inferior vena cava filter occlusion, in that while early intervention is best, the benefit may still be derived several months after an acute occlusion.
Jaff said that endovascular intervention can also be suitable in patients at high risk of fatal pulmonary embolism and in those with propagation of deep vein thrombosis despite conventional therapy. Furthermore, once the clot is dealt with, there is a high likelihood of underlying anatomical lesions, such as with May-Thurner syndrome, compression by a pelvic tumour or prior pelvic deep vein thrombosis.
Adding a mechanical device that can debulk or remove a clot “will theoretically result in a shorter treatment time, potentiator of the impact of thrombolytic therapy (thereby allowing for a lower dose of the lytic agent) and may be an option when lysis is relatively contraindicated,” Jaff continued. Data for these concepts will be reported with follow-up for the ATTRACT (Acute venous thrombosis: Thrombus removal with adjunctive catheter-directed thrombolysis) trial—a phase III, open-label, multicentre randomised controlled trial currently enrolling 692 patients with symptomatic and acute proximal deep vein thrombosis at 28 US centres.
The ATTRACT trial, currently in follow-up with results expected to be published in early 2017, is sponsored by the US National Institutes of Health. ATTRACT is “similar” to the Cavent (Catheter-directed venous thrombolysis in acute iliofemoral vein thrombosis) study which included 209 patients with symptomatic, first iliofemoral deep vein thrombosis, randomised to conventional treatment alone or additional catheter-directed thrombolysis. The primary endpoints were Villalta Score at 24 months and iliofemoral patency at six months.
Intervention led to a significant reduction in post-thrombotic syndrome at 24 months (41.1% vs. 55.6% for standard treatment only) and had an improvement in iliofemoral patency at six months (65.9% vs. 47.4% for standard treatment only), Jaff explained. There were 20 bleeding events, three of which were major and five of which were clinically relevant. There were no reported deaths, pulmonary emboli or intracerebral haemorrhages.
“Multiple societies” have come together to create guidelines regarding what should be done for the interventional treatment for deep vein thrombosis, said Jaff. Societies such as the Society for Vascular Surgery and the American Venous Forum believe that so far there are very little data to go on, and that the only group in which there is a strong consideration is early thrombus removal in patients with impending venous gangrene. The American Heart Association also produced guidelines, on which Jaff was the first author, looking at patients “with extensive iliofemoral deep vein thrombosis.” The guidelines suggest that “in patients who have complete or partial thrombosis of any segment of the iliac vein, with or without the involvement of other veins, you should consider intervention,” Jaff reported.
“At the bottom line, we know that anticoagulation does not prevent the development of post-thrombotic venous insufficiency and that morbidity of post-thrombotic venous insufficiency is significant and costly,” Jaff told the audience. “Endovenous intervention for deep vein thrombosis should be considered for iliofemoral deep vein thrombosis and patients with advanced symptoms and low bleeding risk. You need an experienced interventional team to do this.”
New guidelines were published in January 2016 by “a group of multispecialty experts” in the Journal of Thrombosis and Thrombolysis which took “a far more conservative stance on how to manage patients from an interventional standpoint,” Jaff said. These guidelines focused mainly on bleeding risk.
“To wrap up,” Jaff discussed thrombolytics therapy for acute pulmonary embolus. In the short-term, he said, the goals of such therapy are to: dissolve thromboembolic obstruction of the pulmonary arterial tree to reduce pulmonary vascular resistance; rapidly resolve right ventricular pressure overload and improve function; expedite restoration of pulmonary capillary blood flow and effective gas exchange; quickly resolve symptoms; prevent early clinical deterioration and mortality in patients with massive and submassive pulmonary embolism; and decrease the risk of recurrent pulmonary embolism by dissolving the reservoir of thrombus that often remains in the lower extremities or pelvis. The long-term goals are the prevention of chronic thrombo-embolic pulmonary hypertension and preserving the normal haemodynamic response to exercise. However, Jaff noted, “the contraindications of lytic therapy” are very important, of which “there are many”.
Jaff told delegates about a new concept; the Pulmonary Embolism Response Team, or PERT. “If you are interested in pulmonary embolus therapy and you like to do interventions you might make one decision. If you are a pulmonary/critical care physician, you might be much happier putting the patient in an intensive care unit on heparin and watching them. In our facility we created this rapid response team, which allows for immediate access of all the specialities involved to help decide what to do for these very sick patients with serious pulmonary emboli.”