Evidence-based emergency medicine/critically appraised topic. Thrombolytic therapy for submassive pulmonary embolism?

Study Objective: The purpose of this review was to determine the effectiveness of adding thrombolytics to standard heparin therapy for treatment of submassive pulmonary embolism. Patients with submassive pulmonary embolism were considered to be those with evidence of right ventricular dysfunction but without hemodynamic instability.

Methods: We searched for trials comparing thrombolytics to heparin in the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE. We included only studies assessing the effectiveness of thrombolytic therapy for submassive pulmonary embolism and reported the patient-important outcomes of mortality, recurrent pulmonary embolism, and major hemorrhage.

Results: Two randomized trials met the inclusion criteria; one with a total of 256 patients presenting with submassive pulmonary embolism and the other trial including a subgroup of 46 patients with submassive pulmonary embolism. In the larger study, the relative risk (RR) for mortality, recurrent pulmonary embolism, and major hemorrhage was 1.56 (95% confidence interval [CI] 0.36 to 6.83), 1.17 (95% CI 0.30 to 4.57), and 0.23 (95% CI 0.03 to 1.97), respectively. Our post hoc subgroup analysis of the smaller trial identified 2 deaths and 5 patients with recurrent pulmonary embolism among 23 controls, whereas none of the 23 patients randomized to thrombolytics died or had recurrent pulmonary embolism. None of these findings were statistically significant.

Conclusion: Results of randomized trials comparing the addition of thrombolytic therapy to standard heparin therapy for treatment of submassive pulmonary embolism fail to show any significant differences in clinically important outcomes.