Deep vein thrombosis (DVT) occurs when a blood clot forms in a leg vein. The clot can break up and move to the lungs, leading to a potentially serious blockage in blood flow (pulmonary embolism or PE). Because of the damage to the leg vein, post-thrombotic syndrome (PTS) may develop any time over the next couple of years. Symptoms include leg pain, swelling, skin pigmentation and leg ulcers, leading to loss of mobility. Anticoagulants are the standard treatment for DVT or a clot in a calf vein. These thin the blood to reduce further clots forming and prevent PE; yet PTS can still develop. Thrombolysis breaks down the blood clot. For DVT, drugs such as streptokinase, urokinase and tissue plasminogen activator are infused into a vein in the arm or foot or, in some cases, directly at the site of the clot using a catheter and X-ray control. Bleeding complications, stroke or intracerebral haemorrhage are potential harmful events for both treatments.
The present review showed that thrombolysis may have advantages over standard anticoagulation treatment. Thrombolysis effectively dissolved the clot so that complete clot breakdown occurred more often with thrombolysis than with standard anticoagulant therapy. Blood flow in the affected vein (venous patency) was also better maintained. Four trials (341 participants) continued for over six months and found that fewer people developed PTS when treated with thrombolysis, 43% compared with 64% in the standard anticoagulation treatment group (the number needed to treat was five).
The review results are based on 17 controlled trials that randomised a total of 1103 people with acute DVT (within 21 days of onset of symptoms) to receive thrombolysis or anticoagulant treatment. Trials were carried out principally in the USA, Scandinavia, Germany and the UK. All trials included men and women and the age range was 18 to 75 years with a preponderance of older adults. Those receiving thrombolysis had significantly more bleeding complications than with standard anticoagulation (10% versus 8%). Most bleeding episodes and deaths occurred in the earlier studies. Use of strict eligibility criteria has improved the safety and acceptability of this treatment, with treatment directed by catheter in more extensive clots now the favoured method.