Efficacy of thrombolytic agents in the treatment of pulmonary embolism

Recent guidelines recommend bolus-dose alteplase for treating massive pulmonary embolism (PE). However, the safest and most effective treatment is as yet unknown. In the present study, a meta-analysis of published studies of alteplase infusion, bolus-dose alteplase and streptokinase was performed. The outcome measures were as follows: objective assessment of thrombolysis; all-cause mortality; deaths due to initial PE, major bleeding episodes and recurrent PE; and morbidity. In total, 26 studies were identified; however, only two comparative studies of alteplase infusion versus either bolus-dose alteplase or streptokinase were found. Meta-analysis revealed no significant difference between the three regimens, but was compromised by a paucity of data. Crude analysis of summated data on thrombolytic efficacy from all studies revealed that alteplase infusion was more effective than bolus-dose alteplase (relative risk (RR): 1.95; 95% confidence interval (Cl): 1.19-3.2), whereas streptokinase was more effective than alteplase infusion (RR: 1.27; 95% CI: 1.09-1.47). Alteplase infusion had a lower mortality due to the initial PE than both bolus-dose alteplase and streptokinase (RR: 0.16; 95% CI: 0.05-0.59 and RR: 0.13; 95% CI: 0.04-0.46, respectively). In conclusion, this evidence suggests that the three thrombolytic agents may vary in efficacy. However, large-scale randomised controlled trials are needed to confirm these results.