Clinical Research Directory

Inclusion Criteria: * Age 18 to 80 years. * Acute pulmonary embolism confirmed by computed tomography pulmonary angiography (CTPA). * Interval from symptom onset to diagnosis of 14 days or less. * Intermediate-high-risk PE according to the 2025 Chinese guideline and ESC risk stratification: simplified Pulmonary Embolism Severity Index (sPESI) of 1 or greater; imaging evidence of right ventricular dysfunction (CTPA RV/LV diameter ratio \>= 1.0, or echocardiographic right ventricular dilatation or hypokinesia); and troponin I or T above the upper limit of normal. * Eligible for percutaneous catheter-directed intervention: contraindication to, or failure of, systemic thrombolysis, or clinical deterioration during anticoagulation therapy. * Thrombus visible in the main pulmonary artery and/or lobar arteries on CTPA. * Provision of written informed consent. Exclusion Criteria: * Haemodynamic instability at enrolment: cardiac arrest; need for ongoing cardiopulmonary resuscitation; or systolic blood pressure below 80 mmHg for more than 15 minutes unresponsive to fluid resuscitation and vasopressors. * Active bleeding; known coagulopathy (INR \> 2.0 or platelet count \< 50 x 10\^9/L); intracranial haemorrhage within the previous 90 days, or intracranial tumour or vascular malformation; major surgery, major trauma, or gastrointestinal bleeding within the previous 30 days; known heparin allergy or history of heparin-induced thrombocytopenia. * Planned catheter-directed thrombolysis or systemic thrombolysis. * Known chronic thromboembolic pulmonary hypertension; severe left ventricular dysfunction (LVEF \< 30%); severe valvular heart disease (moderate-to-severe aortic stenosis or mitral regurgitation); end-stage renal disease (eGFR \< 30 mL/min/1.73 m2 or dialysis dependence); pregnancy or breastfeeding. * Anatomical contraindications: intracardiac or pulmonary arterial mass on CTPA or ultrasound suggesting tumour or infective embolus; severe stenosis or occlusion of the inferior vena cava or the iliofemoral venous route. * CTPA image quality inadequate for independent core laboratory reading. * Expected survival of less than 6 months due to severe comorbidity (for example, advanced malignancy); inability or unwillingness to complete the follow-up schedule. * Participation in another clinical study that could interfere with endpoint assessment; any other condition that, in the investigator's judgement, makes participation inappropriate.