This study is a prospective, multicenter, randomized controlled trial of the FlowTriever System plus anticoagulation compared to anticoagulation alone for intermediate-risk acute PE.

Inclusion Criteria:

1. Age at enrollment ≥ 18 years

2. Objective evidence of a proximal filling defect in at least one main or lobar pulmonary artery, as confirmed by CTPA, pulmonary angiography, or other imaging modality

3. RV dysfunction, as defined as one or more of the following: RV/LV ratio ≥ 0.9 or RV dilation or hypokinesis

4. At least two additional risk factors, identified by at least one measure in two separate categories noted below:

   a. Hemodynamic: i. SBP 90-100mmHg ii. Resting heart rate > 100 bpm b. Biomarker: i. Elevated* cardiac troponin (troponin I or troponin T, conventional or high sensitivity) ii. Elevated* BNP or NT-proBNP iii. Elevated venous lactate ≥2 mmol/L * Elevated, meaning at or above the upper limit of normal, per local standards for the assay used c. Respiratory: i. O2 saturation < 90% on room air ii. Supplemental O2 requirement ≥ 4 L/min iii. Respiratory rate ≥ 20 breaths/min iv. mMRC score > 0

5. Symptom onset within 14 days of confirmed PE diagnosis

6. Willing and able to provide informed consent

Exclusion Criteria:

1. Unable to be anticoagulated with heparin, enoxaparin or other parenteral antithrombin

2. Presentation with hemodynamic instability* that meets the high-risk PE definition in the 2019 ESC Guidelines1, including ANY of the following

   1. Cardiac arrest OR
   2. Systolic BP < 90 mmHg or vasopressors required to achieve a BP ≥ 90 mmHg despite adequate filling status, AND end-organ hypoperfusion OR
   3. Systolic BP < 90 mmHg or systolic BP drop ≥ 40 mmHg, lasting longer than 15 min and not caused by new-onset arrhythmia, hypovolemia, or sepsis * Patients who are stable at time of screening or randomization (i.e., SBP ≥ 90 mmHg and adequate organ perfusion without catecholamine or vasopressor infusion) may be included despite initial presentation including temporary, low-dose catecholamines or vasopressors, or temporary fluid resuscitation.

3. Known sensitivity to radiographic contrast agents that, in the Investigator's opinion, cannot be adequately pre-treated

4. Imaging evidence or other evidence that suggests, in the opinion of the Investigator, the patient is not appropriate for catheter-based intervention (e.g., inability to navigate to target location, clot limited to segmental/subsegmental distribution, predominately chronic clot)

5. End stage medical condition with life expectancy < 3 months, as determined by the Investigator

6. Current participation in another drug or device study that, in the investigator's opinion, would interfere with participation in this study

7. Current or history of chronic thromboembolic pulmonary hypertension (CTEPH) or chronic thromboembolic disease (CTED) diagnosis, per 2019 ESC Guidelines1

8. If objective testing was performed*, estimated RV systolic pressure > 70 mmHg on standard of care echocardiography * If clinical suspicion of acute-on-chronic PE, chronic obstruction, or chronic thromboembolism, echocardiographic estimated RVSP must be confirmed ≤70 mmHg to meet eligibility. Pressure assessment not required if Investigator attests to absence of such clinical suspicion

9. Administration of advanced therapies (thrombolytic bolus, thrombolytic drip/infusion, catheter-directed thrombolytic therapy, mechanical thrombectomy, or ECMO) for the index PE event within 30 days prior to enrollment

10. Ventricular arrhythmias refractory to treatment at the time of enrollment

11. Known to have heparin-induced thrombocytopenia (HIT)

12. Subject has any condition for which, in the opinion of the investigator, participation would not be in the best interest of the subject (e.g., compromise the well-being or that could prevent, limit, or confound the protocol-specified assessments). This includes a contraindication to use of FlowTriever System per local approved labeling

13. Subject is currently pregnant

14. Subject has previously completed or withdrawn from this study