The primary objective of this trial is to evaluate the safety and efficacy of treatment with anticoagulation alone versus anticoagulation and mechanical aspiration thrombectomy with the Indigo Aspiration System for the treatment of intermediate-high risk acute pulmonary embolism (PE).

Inclusion Criteria:

1. Age 18-80 years old
2. Clinical signs and symptoms consistent with acute PE with duration of 14 days or less
3. Objectively confirmed acute PE, based on computed tomographic pulmonary angiography (CTPA) imaging showing a filling defect in at least one main or proximal lobar pulmonary artery
4. Classification of intermediate high-risk PE as demonstrated by right ventricular dysfunction with RV/LV ratio ≥1.0 on CTPA and elevated cardiac biomarkers, including cardiac troponin, BNP, and/or NT-pro BNP above the upper limit of normal
5. Jugular or femoral access deemed suitable to accommodate pulmonary artery intervention with the Indigo Aspiration System
6. Informed consent is obtained from either the patient or legally authorized representative (LAR)

Exclusion Criteria:

1. Administration of thrombolytic agents or glycoprotein IIb/IIIa receptor antagonist within 30 days prior to baseline imaging

2. Hemodynamic instability with any of the following present:

   1. Cardiac arrest
   2. Obstructive shock or persistent hypotension defined as systolic blood pressure (BP) <90 mmHg or an acute drop in systolic BP ≥40 mmHg for >15 min, or requiring vasopressor or inotropic support to achieve a systolic BP ≥90 mmHg

3. Patients on ECMO

4. National Early Warning Score (NEWS) 2 ≥9

5. History, imaging or hemodynamic findings consistent with chronic thromboembolic pulmonary hypertension (CTEPH) or chronic thromboembolic disease (CTED) diagnosis

6. Imaging evidence or other evidence that suggests, in the opinion of the Investigator, that catheter-based intervention is not appropriate for the patient

7. Allergy, hypersensitivity, or heparin induced thrombocytopenia (HIT)

8. Contraindication or sensitivity to iodinated intravascular contrast that cannot be adequately premedicated

9. <45 mL/min creatinine clearance

10. Severe active infection (e.g. sepsis) requiring treatment at time of enrollment

11. Active bleeding or disorders contraindicating anticoagulant therapy

12. Hemoglobin <10 g/dL

13. Platelets <100,000/μL

14. INR >3

15. Cardiovascular or pulmonary surgery within last 7 days

16. Primary brain or metastatic brain cancer

17. Life expectancy <90 days

18. Pregnancy

19. Intracardiac thrombus (right atrium, right ventricle clot in transit) or thrombus in the inferior vena cava identified on baseline imaging

20. Current participation in another investigational drug or device trial that may confound the results of this trial. Studies requiring extended follow-up for products that were investigational but have since become commercially available are not considered investigational studies.

21. Other medical, social, or psychological conditions that, in the opinion of the Investigator, precludes the patient from appropriate consent, could limit the patient's ability to participate in the trial, including compliance with follow-up requirements, or that could impact the scientific integrity of the trial