Thrombolytic therapy for pulmonary embolism

Background Thrombolytic therapy is usually reserved for patients with clinically serious or massive pulmonary embolism ( PE). Evidence suggests that thrombolytic agents may dissolve blood clot 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. Objectives To assess the effectiveness and safety of thrombolytic therapy in patients with acute PE. Search strategy We sought trials through the Cochrane Peripheral Vascular Diseases Group's Specialised Register ( January 18, 2006), the Cochrane Central Register of Controlled Trials ( CENTRAL) (The Cohrane Library Issue 1, 2006), MEDLINE (January 1966 to December 2004), EMBASE, CINAHL, LILACS and SCISEARCH ( all November 2004). We also searched individual trial collections and private databases, along with bibliographies of relevant articles. Relevant medical journals were handsearched. The most recent search was on February 6, 2006. Selection Criteria Randomised controlled trials 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. Data Collection and analysis Two authors (DB and WQ) assessed the eligibility and quality of trials and extracted data. Main results Results were similar between thrombolytics compared with heparin alone or placebo and heparin 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. Authors' conclusion We cannot conclude whether thrombolytic therapy is better than heparin for pulmonary embolism based on the limited evidence found. 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.