Background: The role of thrombolytic treatment in patients with intermediate high-risk pulmonary embolism (IHR-PE) remains controversial. In this study, we assessed whether systemic thrombolysis decreases hemodynamic decompensation and mortality in a cohort of unselected patients with intermediate-high risk compared to patients with conventional anticoagulation.

Methods and Results: Between January 2014 and December 2018, 137 IHR-PE subjects were identified among 539 consecutive patients treated for symptomatic pulmonary embolism. In 35 patients (25.5%), systemic thrombolysis was used. Propensity score matching was performed based on 17 pre-treatment variables to reduce selection bias. Primary outcome was hemodynamic decompensation defined by systolic hypotension, need for catecholamines or signs of end organ hypoperfusion and all-cause mortality within hospital stay. Furthermore, secondary outcomes such as one-year survival and safety outcomes such as bleeding events within hospital stay were analyzed.

The effects of systemic thrombolysis and conventional anticoagulation were compared in 55 matched patients with IHR-PE (systemic thrombolysis: n=21; anticoagulation= 34). Thrombolysis was associated with a reduction (0% vs. 31%; p=0.004) of the primary outcome during hospitalization and a one-year survival benefit (100% vs. 83.2%; p=0.036). Severe bleeding events occurred in 4.8% vs. 0%, p=0.382, and moderate bleeding was observed in 14.3% vs. 7.1%, p=0.359, in patients with thrombolysis compared to anticoagulation, respectively.

Conclusion: Thrombolysis was associated with a reduction of hemodynamic decompensation and mortality during hospitalization and lower all-cause mortality after one year in an unselected group of patients with IHR-PE. Further studies are required to improve the therapy of IHR-PE and to identify the subgroup of patients that might benefit from thrombolytic therapy.

Key Words: - acute pulmonary embolism – intermediate high risk – thrombolysis – mortality - bleeding