Low-dose Systemic Tissue-type-plasminogen-activator Compared to Conventional Anti-coagulation for the Treatment of Intermediate-high Risk Pulmonary Embolism.

Background: Pulmonary embolism (PE) is a frequent cause of death. Acute PE may be treated either with full anticoagulation (AC) alone or thrombolytic therapy with systemic tissue-- type-plasminogen-activator (tPA) based on risk assessment. Currently, AC is the standard of care for most patients with intermediate-high-risk PE, with low-dose tPA emerging as an effective alternative. However, studies directly comparing the efficacy and safety of low-dose tPA to AC are lacking in this patient population.

Objective: The aim of this study was to retrospectively compare the efficacy and safety of low-- dose tPA, compared to AC alone in right ventricular function and in-hospital mortality and bleeding complications in patients presenting with intermediate-high risk PE.

Methods: This is a single-center, retrospective cohort trial conducted at a university hospital. A total of 148 patients were screened, and 88 patients qualified for this study. The primary endpoints were changes in right ventricular function on echocardiogram in 24 hours, in-hospital mortality, and major bleeding complications.

Results: Eighty-eight consecutive patients with intermediate high-risk PE were included. Twenty- six patients (29.5%) received low-dose systemic tPA administered via intravenous infusion, and 62 patients (70.4%) received standard full-dose anticoagulation. There were no significant differences in baseline vital signs or PESI scores between the low-dose tPA and the AC group. Patients in the low-dose tPA group had worse RV function and higher troponin levels at baseline but showed significant improvement in all RV parameters assessed during the 24-hour follow-up. In comparison, there was no significant improvement in RV function in the AC group. There were more bleeding events in the AC group. LOS was shorter in the low-dose tPA group.

Conclusion: Treatment with low-dose prolonged infusion of tPA may be an effective and safe therapy in patients with intermediate-risk PE. Compared to AC, low-dose tPA was effective in decreasing PASP and restoration of RV function.