In cases of extensive deep vein thrombosis, supplementary treatment with catheter-directed thrombolysis can reduce the number of cases of post-thrombotic chronic leg problems. We therefore believe that adults with acute thrombosis in the pelvis or upper thigh and with a low risk of bleeding should be considered for this type of treatment.
Post-thrombotic syndrome is a chronic condition that develops gradually after a deep vein thrombosis. The condition is characterised by swelling, a sense of discomfort and heaviness, skin discolouration and, in the most severe cases, the formation of venous ulcers. Even after adequately performed standard treatment with anticoagulation and compression stockings, at least one in four persons develops post-thrombotic syndrome after proximal deep vein thrombosis, i.e. deep vein thrombosis at the level of the popliteal vein and more proximally (1, 2). With deep vein thrombosis that extends up into the upper thigh or the pelvis, the risk of post-thrombotic syndrome is even higher (3).
There is no curative treatment, but accelerated lysis of the clot could probably prevent the development of venous dysfunction, and thereby post-thrombotic syndrome (4). Catheter-directed venous thrombolytic therapy in addition to the standard treatment is therefore being used in a number of institutions world-wide, despite a lack of documentation of its clinical effectiveness (5). Clinical experience and the results of a number of non-controlled studies indicate that the treatment is effective and entails a small risk of bleeding (6). There is no evidence of an increased risk of embolism or other complications. When a thrombolytic agent (alteplase) with a high affinity for fibrin is used, a primary local effect is achieved with a considerably lower dose than with systemic thrombolytic treatment (6).
In a major collaboration, the hospital trusts of the South-Eastern Norway Regional Health Authority conducted the first major randomised, controlled study with evaluation of the clinically relevant effect of supplementary treatment with catheter-based thrombolysis (7). After two years, the incidence of post-thrombotic syndrome was 56 % in those who received standard treatment only, compared with 41 % in those who received supplementary thrombolytic therapy. The study also provides support for what is called the «open vein hypothesis», in that venous rechanneling after six months occurred more frequently in the thrombolysis group and was associated with a lower incidence of post-thrombotic syndrome after two years than in cases without recanalisation (7, 8). We hope that these results, together with those of two ongoing studies in the Netherlands and the USA, will result in better evidence-based practice for these patients (www.clinicaltrials.gov: NCT00970619, NCT00790335).