Adjunctive Catheter-Directed Thrombolysis Evaluated for DVT
August 15, 2017—The Society for Vascular Surgery (SVS) announced the publication of an evaluation of thrombolysis using tissue plasminogen activator (tPA) in lower extremity deep venous thrombosis (DVT) with concomitant femoropopliteal venous segment involvement by Mayin Lin, DO, et al in the Journal of Vascular Surgery Venous and Lymphatic Disorders (JVS:VL; 2017;5:613–620).
The SVS announcement by Paul DiMuzio, MD, who is an Assistant Editor of the society's Journal of Vascular Surgery, noted that the report highlights the benefits of catheter-directed thrombolysis (CDT) in the treatment of DVT. This is in contrast to findings in the ATTRACT (Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis) trial that suggest most patients will not benefit significantly from more aggressive treatment of DVT.
Dr. DiMuzio noted that, although the mainstay of acute DVT treatment is anticoagulation, more aggressive strategies involving lytic therapy (CDT and pharmacomechanical CDT to restore patency and maintain valve function early) may reduce the incidence of postthrombotic syndrome (PTS). This is thought to be true for those presenting with extensive iliofemoral DVT. However, the results of the ATTRACT trial showed no significant difference in PTS after aggressive treatment versus anticoagulation alone. Subgroup analysis did reveal lytic therapy resulted in faster resolution of symptoms at 30 days in patients presenting with severe symptoms, and less moderate/severe PTS in those presenting with iliofemoral DVT.
As reported in JVS:VL, investigators from the Mercy Medical Center in Des Moines, Iowa, led by vascular surgeon David Chew, MD, retrospectively evaluated their single-center results treating acute femoral-popliteal DVT, 93% of which included the iliac veins. The investigators compared 89 patients who underwent CDT versus 102 treated with anticoagulation alone. The CDT was performed using tPA, limited to 3 days, and adjusted according to fibrinogen levels.
The primary endpoints, measured at 3 months, significantly favored CDT versus anticoagulation alone: deep vein patency, 75% versus 11%; lower incidence of PTS, 21% versus 73%; and reduced occurrence of valve dysfunction, 23% versus 67%. In addition, their protocols resulted in only 6% major bleeding after CDT compared with 15% for anticoagulation, and no significant difference in pulmonary embolism or mortality.
In the SVS press release, Dr. Lin commented: “The results of our single-center study suggest that CDT is superior to standard anticoagulation alone in restoring patency to the femoral-popliteal venous segment in lower extremity DVT that was associated with proximal extension. This was achieved without an increased risk of bleeding associated with the use of tPA.”
Limitations to this study include the two groups differed in age (CDT patients being younger) and increasing age was determined to be a significant risk factor for bleeding; PTS is a chronic condition that typically occurs years after acute DVT and the improvement of symptoms at 3 months does not necessarily mean avoidance of PTS (this review is targeted at those patients with acute [< 45 d] DVT); and, the size of the study is small compared with the larger trials.
Dr. DiMuzio advised that the investigators’ protocol limited lysis to 3 days and relied on measurement of fibrinogen levels to avoid systemic fibrinolysis and bleeding. He added, "Physicians who treat patients with acute DVT will rely heavily on the extraordinary efforts of those who perform randomized trials such as the ATTRACT trial. However, excellent results achieved in selected patients using refined protocols speak loudly in the ongoing debate of 'to lyse or not to lyse.'"
The April 2017 issue of Endovascular Today provides a review and commentary on the ATTRACT 2-year data that were presented by Suresh Vedantham, MD at the Society of Interventional Radiology 2017 annual scientific meeting held March 4–9 in Washington, DC (2017;4:46–49).