Ventilation and Perfusion Scan in Pulmonary Embolism Following Catheter Directed Thrombectomy Versus Anticoagulation Alone

Clinical presentation of acute pulmonary embolism (PE) is complex and varied and not uncommonly involves respiratory failure with dyspnea or hypoxia. Patients with persisting signs of respiratory failure despite anticoagulation, may benefit from catheter directed thrombectomy. Additionally, patient who receive thrombectomy are likely to have a lower residual thrombus burden measurable by ventilation-perfusion (V/Q) scan, and thereby less likely to develop chronic sequela, including chronic thromboembolic pulmonary hypertension (CTEPH) and post PE syndrome.

Acute pulmonary embolism (PE) is a common disease with variable presentation and clinical outcomes. Chronic sequelae including chronic thromboembolic pulmonary hypertension (CTEPH) and post-PE syndrome are common pathologies for patient who survive the already significant inpatient mortality, and have a significant impact on both quality of life and life expectancy. To date, the ELOPE trial is the only study to prospectively compare quality of life (QoL) and dyspnea measures and six-minute walk distance (6MWD) to cardiopulmonary exercise test, revealing worse post-PE syndrome in select populations, however this study is limited to a single arm that received anticoagulation alone. New catheter directed therapies, developed in response to such poor outcomes, provide treatment options for acute PE patients when first line therapies including anticoagulation are contraindicated or have failed.

Long term studies utilizing imaging have shown a majority of patients diagnosed with PE have residual pulmonary thrombi after 6 months, which is likely to be a large contributor to the development of CTEPH. Ventilation-perfusion (V/Q) scans remain the gold standard for detection of both acute and chronic pulmonary embolism and will serve as a primary outcome measure at 6 months post initial treatment. Clinical measures including 6MWD, QoL and dyspnea questionaries will be assessed prior to discharge, and at 1 and 6 months, in order to characterize the development of chronic symptomatology.

Eligibility Criteria:
Inclusion Criteria:

1. Age \>18 years
2. Clinical signs and symptoms consistent with acute PE
3. Echocardiogram, CT pulmonary angiogram (CTPA) or pulmonary angiographic evidence of proximal filling defect in at least one main or lobar pulmonary artery
4. Scheduled for PE treatment with catheter directed therapy and systemic anticoagulation or anticoagulation alone per the investigator's discretion
5. Signs of respiratory failure including a. arterial blood saturation \<90%, or b. partial arterial oxygen pressure \<60 mmHg, or c. persistent tachypnea with respiratory rates \> 20/min

Exclusion Criteria:

1. Unable to be anticoagulated with heparin or alternative therapy
2. Diagnosis with a minor PE without signs of right ventricular (RV) dysfunction
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 opinion of the Investigator, the patient is not appropriate for mechanical thrombectomy intervention (e.g., inability to navigate to target location or predominately chronic clot)
5. Life expectancy \<6 months, as determined by the Investigator