Systematic review and meta-analysis for thrombolysis treatment in patients with acute submassive pulmonary embolism.

Purpose: The aim of this systematic review was to evaluate the efficacy and safety of thrombolytic treatment in patients with submassive pulmonary embolism (PE).

Methods: An electronic search was carried out based on the databases from MEDLINE, Embase, Science Citation Index (SCI), and the Cochrane Library. We included prospective, randomized, and clinical trials in thrombolysis with heparin alone in adults who had evidence of right ventricular dysfunction and normotension. The main endpoints consist of mortality, recurrent PE, and bleeding risk. The relative risk (RR) and the relevant 95% confidence intervals were determined by the dichotomous variable.

Results: Only seven studies involving 594 patients met the inclusion criteria for further review. The cumulative effect of thrombolysis, compared with intravenous heparin, demonstrated no statistically significant difference in mortality (2.7% versus 4.3%; RR=0.64 [0.29-1.40]; P=0.27) or recurrent PE (2% versus 5%; RR=0.44 [0.19-1.05]; P=0.06). Thrombolytic therapy did not increase major hemorrhage compared with intravenous heparin (4.5% versus 3.3%; RR=1.16 [0.51-2.60]; P=0.73), but it was associated with an increased minor hemorrhage (41% versus 9%; RR=3.91 [1.46-10.48]; P=0.007).

Conclusion: Compared with heparin alone, neither mortality nor recurrent PE is reduced by thrombolysis in patients with submassive PE, and it does not reveal an increasing risk of major bleeding. In addition, thrombolysis also produces the increased risk of minor bleeding; however, no sufficient evidence verifies the thrombolytic benefit in this review, because the number of patients enrolled in the trials is limited. Therefore, a large, double-blind clinical trial is required to prove the outcomes of this meta-analysis.