While presenting on the trials and updates in deep vein thrombosis, Stephen Kee, Professor of Radiology and Chief of Interventional Radiology, UCLA Health System in Los Angeles, speaking at CIRSE 2015, told delegates that there was “an information overload” when Pubmed was searched for “deep vein thrombosis”. There are over 65,000 articles online, he noted, with 42,000 relating to the treatment of the condition, 1,850 dealing with thrombolysis and 474 pertaining to aggressive therapy. “How do we make sense of all this data and what questions really need answering?” Kee asked.
“Is there clear data regarding anything more aggressive than anticoagulation,” he asked and went on to state that there was “some data” but it is “not that clear”. He referred to the Cochrane Collaborative Review article on thrombolysis for acute deep vein thrombosis that was published in January 2014, and summarised all randomised trials of anticoagulation vs. thrombolysis plus anticoagulation specifically in acute patients, whose symptoms began less than 21 days prior to presentation.
“[In the meta-analysis]The delivery of the thrombolytic drug used varied from systemic, to locoregional, to catheter-directed and the drug varied from streptokinase, to urokinase, to t-PA. In summary, complete clot lysis and venous patency occurred more often in the lysis group (p=0.004). Post-thrombotic syndrome was highly significantly reduced in the lysis group (p<0.0001), as was leg ulceration. However, unfortunately, bleeding complications were more common in the lysis group (p<0.0006) and this included three strokes, that were all in trials before 1990,” said Kee. [However]There remains a definite fear potential intracranial complications when clinicians are considering referring for thrombolysis, he added.
“What do we believe? Proximal deep vein thrombosis responds well to lysis and stenting and early treatment will reduce long-term disability. Modern regimens for t-PA and heparin are safe and will result in few complications (practically no intracranial problems). Mechanical devices can reduce the need for t-PA and shorten therapy. Compared with conventional therapies, invasive treatment remains cost-effective. How do we prove this? There is a large trial that is in the process of data collection ATTRACT (Acute venous thrombosis: thombus removal with adjunctive catheter-directed thrombolysis) that enrolled 692 acute patients and is expected to start reporting in Spring 2017,” Kee added.
Current management depends on practice patterns
“Most deep vein thrombosis cases seen in the US and Europe are patients admitted to another service and then referred to interventional radiology. What you need to find out is the extent of clot, establish whether one or both legs are involved, try and understand the underlying cause and any contraindication to t-PA. We need to determine the age of the clot, whether a filter was used or not, use of elasticated compression stockings, anticoagulation and thrombotic profile. More practices are developing out-patient clinics where patients are seen with acute and chronic deep vein thrombosis. An acute deep vein thrombosis is one that is less than two weeks old, however, even with a perfect historian, the clot is often of varying age. Often, of the biggest initial clinical decisions is planning the access vessels. Most begin with an ipsilateral popliteal vein stick, recanalisation of the veins to the inferior vena cava, some type of mechanical/lytic catheter, and subsequently venoplasty, with or without the use of a stent. Recanalisation is best done with a low profile catheter such as a 4F glide catheter and wire.
“Practices vary greatly with the use of the mechanolytic device. We see everything from Angiojet (Boston Scientific), Angiovac (Angiodynamics), Pronto (Vascular Solutions), Trellis (Medtronic, now off market), Trerotola basket (Arrow), Cleaner (Rex Medical), Ekos (BTG), McNamara catheter (Covidien) and Unifuse (Angiodynamics). There is no data confirming which device is best, cheapest, quickest, or safest. We currently use Ekos with overnight lysis in a step-down unit and reserve mechanical devices for clean-up,” said Kee.
“There is some evidence to support what we all practice and believe, but not much. Continued reporting of the CaVenT trial, and soon the ATTRACT trial, will hopefully provide direction for the future. There is practically no evidence as to what to do in chronic (> six weeks of symptoms) patients. General recommendations are keep your t-PA dose down, use no more than 1–2mg/hour of t-PA, use elasticated compression stockings, venoplasty below the inguinal ligament, plasty and/or stenting above. In terms of chronic disease it is very hard to give any recommendations as the literature is very varied. It is controversial as to whether any treatment helps, but most practitioners use long term anticoagulants and compression stockings. Many believe that venoplasty (and/or stenting) provides additional benefit,” said Kee.
Strong message on use of IVC filters
Responding to a question from the audience on Kee’s practice on the use of inferior vena cava filters for patients during lysis for deep vein thrombosis, he said: “I think today, if I feel that there may be an inferior vena caval thrombosis or if the patient or their family ask me if I am using one, I place one. There is very little to zero evidence to favour the placement or the lack of placement of a caval filter during lysis. The recommendation would be that if you have any concerns, the use of a filter is reasonable and quite safe. But, you have to be sure that you take that filter out. If you put that filter in and the patient goes home, then you might never see that patient again until they have both legs clotted. Yes, I support the use of filters in such patients, in appropriate situations but only if you are willing to take that responsibility of being in charge of getting that filter out.”