• Age 18 years or older

• Objectively confirmed acute PE with first symptoms occurring 2 weeks or less before randomization. Objective confirmation is based on at least one of the following criteria: (a) at least one segmental ventilation-perfusion mismatch on lung scanning; (b) a spiral computed tomography pulmonary angiography or pulmonary angiography showing a filling defect or an abrupt obstruction of a segmental or more proximal pulmonary artery

• Acute PE confirmed within 24 hours prior to randomization

• Elevated risk of early death, or of hemodynamic collapse, or PE recurrence, indicated by at least one of the following criteria: (a) systolic blood pressure ≤ 110 mm Hg over at least 15 minutes upon enrolment, (b) temporary need for fluid resuscitation and/or treatment with low-dose catecholamines, provided that the patient could be stabilized within 2 hours of admission and maintains SBP of ≥ 90 mmHg and adequate organ perfusion without catecholamine infusion; (c) respiratory rate \> 20/min or oxygen saturation on pulse oximetry SpO2 \<90% o(or partial arterial oxygen pressure \< 60 mm Hg) at rest while breathing room air, (d) documented history of chronic symptomatic heart failure

• Right ventricular dysfunction indicated by RV/LV diameter ratio \>1.0 on echocardiography apical four-chamber or subcostal four-chamber view or on Computed Tomography Pulmonary Angiography (transverse plane)

• Serum troponin I or T concentration above the upper limit of local normal using a high-sensitivity assay

• Ability to randomize the patient within 6 hours after the investigator receives the results of the second of the two criteria for RV dysfunction (RV/LV diameter ratio \>1.0) and myocardial injury (serum troponin I or T concentration above the upper limit of local normal), whichever comes latest.

• Signed informed consent form