MECHANICAL THROMBECTOMY SYSTEM FOR THE TREATMENT OF INTERMEDIATE-RISK ACUTE PULMONARY EMBOLISM: THE CLEAR STUDY

Mechanical Thrombectomy System for the Treatment of Intermediate-Risk Acute Pulmonary Embolism: The CLEAR Study

Mechanical Thrombectomy System for the Treatment of Intermediate-Risk Acute Pulmonary Embolism: The CLEAR Study

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Introduction


Acute pulmonary embolism (PE) is a life-threatening condition caused by the obstruction of pulmonary arteries by thrombi, leading to impaired oxygenation and hemodynamic instability. Intermediate-risk PE, also known as submassive PE, is characterized by right ventricular (RV) dysfunction without hemodynamic collapse. While systemic anticoagulation remains the standard treatment, mechanical thrombectomy has emerged as a promising intervention for improving outcomes in intermediate-risk PE patients. The CLEAR (Clinical Evaluation of a Mechanical Thrombectomy System for Acute Pulmonary Embolism) Study investigates the safety and efficacy of a novel mechanical thrombectomy system for treating intermediate-risk PE.



Study Objectives


The primary objectives of the CLEAR study are:




  • To evaluate the effectiveness of a mechanical thrombectomy system in rapidly reducing pulmonary clot burden.

  • To assess the impact on right ventricular strain and hemodynamic parameters.

  • To determine the safety profile, including the risk of bleeding and procedural complications.


Methods


Study Design


  • Multicenter, prospective, single-arm clinical study.

  • Inclusion of patients with intermediate-risk PE, defined by:

    • Confirmed pulmonary embolism on CT pulmonary angiography (CTPA).

    • RV dysfunction on echocardiography or elevated cardiac biomarkers (troponin, BNP).

    • Absence of sustained hypotension or shock.




Intervention: Mechanical Thrombectomy System


  • The study evaluates a catheter-based mechanical thrombectomy device designed to aspirate and remove thrombi from the pulmonary arteries.

  • The system utilizes large-bore aspiration technology or rotational clot disruption to facilitate rapid clot removal.

  • The procedure is performed under fluoroscopic guidance in a catheterization lab or hybrid operating room.


Outcome Measures


  • Primary Efficacy Endpoint: Improvement in right ventricular-to-left ventricular (RV/LV) ratio at 48 hours post-procedure.

  • Secondary Endpoints:

    • Clot burden reduction on follow-up CTPA.

    • Changes in pulmonary artery pressure.

    • Symptomatic improvement (oxygenation, dyspnea, hemodynamics).

    • Procedural success rate.



  • Safety Endpoints:

    • Major bleeding (as per ISTH criteria).

    • Hemodynamic instability requiring rescue therapy.

    • Device-related complications (vascular injury, embolization).




Preliminary Results



  • Early data suggests a significant reduction in RV/LV ratio within 48 hours post-thrombectomy.

  • Procedural success rates exceed 85%, with minimal bleeding complications compared to systemic thrombolysis.

  • The majority of patients demonstrate rapid symptom relief, reduced oxygen requirements, and improved hemodynamic parameters.


Clinical Implications



  • Potential to bridge the gap between systemic anticoagulation and catheter-directed thrombolysis, offering a non-lytic treatment option for intermediate-risk PE patients.

  • Reduced bleeding risk compared to systemic thrombolytics, making it suitable for patients at high bleeding risk.

  • Shortened hospital stay and improved recovery by enabling early hemodynamic stabilization.


Conclusion


The CLEAR study highlights the feasibility and effectiveness of mechanical thrombectomy for intermediate-risk PE, demonstrating improved RV function and symptom relief with a favorable safety profile. Further randomized trials are warranted to compare mechanical thrombectomy with standard therapies and refine patient selection criteria for optimal outcomes.


https://cvia-journal.org/thrombectomy/

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