Thrombolytic therapy for pulmonary embolism

Thrombolytic therapy is usually reserved for patients with clinically serious or massive pulmonary embolism (PE). Evidence suggests that thrombolytic agents may dissolve blood clots more rapidly than heparin and might reduce the death rate associated with PE. However, there are still concerns about the possible risk of adverse effects of thrombolytic therapy, such as major or minor haemorrhages. This is an update of a Cochrane review first published in 2006.

To assess the effectiveness and safety of thrombolytic therapy in patients with acute PE.

For this update the Cochrane Peripheral Vascular Diseases Review Group searched their Specialised Register (last searched April 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched Issue 2, 2009). We also searched individual trial collections and private databases, along with bibliographies of relevant articles. Relevant medical journals were handsearched.

Randomised controlled trials (RCTs) that compared thrombolytic therapy with placebo or heparin or surgical intervention in patients with acute PE. We did not include trials comparing two different thrombolytic agents or different doses of the same thrombolytic drug.

Two authors (DB and WQ) assessed the eligibility and quality of trials and extracted data.

We included eight trials, with a total of 679 patients, in this review. Results between thrombolytics compared with heparin alone or placebo and heparin were similar in terms of: a) death rate: odds ratio (OR) 0.89; 95% confidence interval (CI) 0.45 to 1.78; b) recurrence of pulmonary embolism: OR 0.63; 95% CI 0.33 to 1.20; c) major haemorrhagic events: OR 1.61; 95% CI 0.91 to 2.86; d) minor haemorrhagic events: OR 1.98; 95% CI 0.68 to 5.75.We found no trials comparing thrombolytic therapy to surgical intervention.Using recombinant tissue-type plasminogen activator (rt-PA) and heparin together compared to heparin alone appeared to reduce the need for further treatment for in-hospital events (OR 0.35; 95% CI 0.17 to 0.71).Thrombolytics improved haemodynamic outcomes, perfusion lung scanning, pulmonary angiogram assessment and echocardiograms to a greater extent than heparin alone.

Based on the limited evidence found we cannot conclude whether thrombolytic therapy is better than heparin for pulmonary embolism. More double-blind RCTs, with subgroup analysis of patients presenting with haemodynamically stable acute pulmonary embolism compared to those patients with a haemodynamic unstable condition, are required.