Standard vs Ultrasound-assisted Catheter Thrombolysis for Submassive Pulmonary Embolism

The study is an investigator-initiated trial comparing two different catheters (standard versus ultrasound assisted) for the treatment of acute high risk pulmonary embolism (blood clots in lung arteries with evidence or heart strain). Patients already planned for the procedure will be randomized to standard catheter-directed thrombolysis (CDT) or to ultrasound-assisted catheter thrombolysis (USAT). Both catheters are currently used routinely in practice for the treatment of pulmonary embolism, but it is not known if USAT is superior to standard CDT, the former being much more expensive and more commonly used.

The purpose of the study is to learn about which catheter-directed therapy is more suitable for patients with pulmonary embolism (PE), who are candidates for both standard catheter directed therapy (CDT), and ultrasound-assisted catheter directed therapy (USAT), and to provide information regarding the cost effectiveness of the two different types of treatment. A total of 80 patients are planned to be recruited. All medication administration, procedures or in-hospital tests will be performed as routine clinical practice. The study will compare short term and long term outcomes: resolution of blood clots on CT scan, right ventricular size improvement, quality of life and symptoms at 3 and 12 months, and cost effectiveness.

Acute pulmonary embolism (PE) accounts for 5-10% of in-hospital deaths. Systemic anticoagulation (AC) is the standard of care and thrombolysis is recommended for those at a higher mortality risk. Catheter-directed therapies, mainly standard catheter-directed thrombolysis (CDT) and ultrasound-accelerated thrombolysis (USAT), have been introduced as new, more effective, and safer treatment modalities. USAT is a modification of standard catheter thrombolysis, utilizing a system of local ultrasound to dissociate the fibrin matrix of the thrombus, allowing deeper penetration of lytics. However, there is limited data comparing the two treatments. More rapid clearance of pulmonary thrombus by USAT compared to standard CDT may prove to be more effective regarding clinical outcomes and cost (e.g. via reduced length of ICU and hospital stay). Alternatively, if thrombus clearance is similar, the cost of USAT may exceed the cost of CDT (equipment and disposables), without offering any potential advantage.

This controlled, randomized study seeks to determine if ultrasound acceleration adds any benefits in the outcomes and costs of catheter-directed thrombolysis for patients with acute submassive PE. The treatment with CDT or USAT are standard of care for submassive PE and participants will be randomized to receive one treatment or the other. Participants will have follow up visits at 3 months and 12 months post procedure. All the procedures, tests, and follow up visits are according to current standard of care.

Eligibility Criteria:
Inclusion Criteria:

* Patients eligible for catheter directed thrombolysis per the study protocol for submassive pulmonary embolism (PE)

  * CT or echocardiographic RV strain (defined as RV/LV ratio \>1)
  * without persisting hypotension \<90mmHg or drop of systolic blood pressure by at least 40mm Hg for at least 15 minutes with signs of end-organ hypoperfusion (cold extremities or low urinary output \<30 mL/h or mental confusion)
* without the need of catecholamine support
* without the need of cardiopulmonary resuscitation

Exclusion Criteria:

* Pregnancy
* Index PE symptom duration \>14 days
* High bleeding risk (any prior intracranial hemorrhage, known structural intracranial cerebrovascular disease or neoplasm, ischemic stroke within 3 months, suspected aortic dissection, active bleeding or bleeding diathesis, recent spinal or cranial/brain surgery, recent closed-head or facial trauma with bony fracture or brain injury)
* Participation in any other investigational drug or device study
* Life expectancy \<90 days
* Inability to comply with study assessments