Post Pulmonary Embolism In Patients Treated With Catheter Based Therapy

Despite advances in care, by some estimates, pulmonary embolism (PE) remains the third leading cause of cardiovascular death.

The AHA/ACC Acute PE Clinical Categories are designed to describe the severity and prognosis of PE by integrating various clinical, laboratory, and imaging parameters. The least severe category, Category A, focuses on asymptomatic and incidentally diagnosed PE. Patients with Category A acute PE are typically identified on a CT performed for another indication and in the absence of clinical suspicion of PE. Category B focuses on patients with symptomatic acute PE and low risk of adverse outcomes by validated severity indices (eg, PESI \[Pulmonary Embolism Severity Index\] ≤85, simplified PESI \[sPESI\] <1, Hestia <1). Category C focuses on symptomatic disease with increased risk of adverse outcomes by validated severity index (eg, PESI >85, sPESI ≥1, Hestia ≥1).

Category D focuses on pre-cardiopulmonary failure states, such as normotensive shock or approaching need for ventilatory support. The most severe category, Category E, focuses on cardiopulmonary failure states. The subcategories differentiate patients with recurrent or persistent hypotension (hemodynamic collapse) with cardiogenic shock from patients with refractory cardiogenic shock or cardiac arrest.

Follow-up studies demonstrated that after an episode of acute PE, up to half of patients report a functional limitation and a decreased quality of life, which also have been increasingly recognized as long-term complications of acute PE. The concept of post-Pulmonary Embolism syndrome (post-PE syndrome) has been recently introduced and is being increasingly recognized as a long-term sequel of PE .

The post-PE syndrome (PPES) includes chronic thromboembolic pulmonary hypertension (CTEPH), chronic thromboembolic pulmonary disease, post-PE cardiac impairment (characterized as persistent right ventricle impairment after PE), and post-PE functional impairment.

Treatment of PE entails anticoagulation as the first-line therapy with thrombolysis reserved for patients with hemodynamic instability. However, given the severe acute and chronic consequences of PE, there has been an increase in the development of catheter-based therapies (CBTs), including catheter-directed thrombolysis (CDT) and percutaneous mechanical thrombectomy (MT), in order to provide rapid reperfusion. Currently, guidelines recommend CBT for patients with high-risk PE at high bleeding risk or have contraindications or failed systemic thrombolysis.

Catheter-directed interventions for patients with acute pulmonary embolism (PE) are rapidly evolving. Currently, the Food and Drug Administration (FDA) has cleared three interventional devices for use in the treatment of acute PE: the EKOS system (EKOS Corporation, Bothell, WA) in 2014, the FlowTriever System (Inari Medical, Irvine, CA, USA) in 2018 and the Penumbra Indigo aspiration system (Penumbra Inc., Alameda, CA, USA) in 2019.

Penumbra Indigo aspiration system is a suction embolectomy device that has the advantage of rapid thrombus removal without the increased bleeding risk associated with thrombolysis. It consists of a flexible small-bore aspiration catheter (8F \& 12F) connected to a continuous aspiration system that generates a continuous aspiration power of -28.5 inHg. The device also employs a separator wire which helps in clot breakdown to facilitate aspiration.

The Lightning aspiration tubing is a part of the Penumbra Indigo aspiration system that has dual pressure sensors with a built-in microprocessor for real-time blood flow monitoring to provide procedural feedback using audiovisual cues, designed to reduce blood loss. It received FDA clearance in April 2020.

While has been proven to be safe in clinical trials, There is no randomized trials to compare this device with medical therapy alone on post pulmonary embolism syndrome.

• The Indigo aspiration system (Device): The Indigo aspiration system (Indigo Aspiration 8-16-F ® System, Penumbra, Alameda, CA, USA) is indicated for use in the peripheral arterial system and the pulmonary arteries, receiving U.S. Food and Drug Administration clearance for PE in December 2019. The PA will be accessed percutaneously, and a diagnostic pulmonary angiogram will be performed to evaluate hemodynamics. The aspiration catheter will be introduced over a 0.035-inch guidewire and advanced to the right or left PA, proximal to the thrombus. Once proximal to the occlusive thrombus, the physician will initiate sustained aspiration with the pump. If appropriate, the separator will be advanced through the catheter to assist with clearing the catheter lumen. Aspiration could be repeated in multiple pulmonary vessels with or without thrombus removal and flushing the catheter between passes. A final pulmonary angiogram and hemodynamic evaluation will be conducted post-Indigo device removal and post procedure

Primary outcomes

• Effectiveness of mechanical thrombectomy on Post pulmonary embolism functional limitation at 6 months follow up [6 months]: Post-PE functional limitation encompasses new or progressive dyspnea and/or exercise intolerance in the absence of other apparent explanations on diagnostic testing apart from PE assessed by Modified Medical Research Council Dyspnea Scale(mMRC) mMRC Dyspnea Scale which measures the severity of breathlessness during daily activities.Grades are Grade 0 (Breathless only with strenuous exercise) Grade 1 (Short of breath when hurrying on level ground or walking up a slight hill) Grade 2 (Walks slower than people of the same age because of breathlessness, or stops when walking at own pace) Grade 3 (Stops for breath after walking about 100 meters or after a few minutes on level ground) Grade 4 (Too breathless to leave the house, or breathless when dressing or undressing) Interpretation: Higher grade = greater functional limitation.
• Effectiveness of mechanical thrombectomy on Post pulmonary embolism cardiac impairment at 6 months follow up [6 months]: Post-PE cardiac impairment is characterized by incomplete RV echocardiographic recovery, as indicated by an intermediate or high echocardiographic probability of pulmonary hypertension (according to the ESC criteria). Criteria for diagnosis post pulmonary embolism impairment include Clinical Criteria Assessed \~6 months after acute PE: Persistent dyspnea (key symptom) Reduced exercise capacity assesed by 6 minutes walk test NYHA functional class ≥ II Unexplained fatigue ± Additional symptoms: Chest discomfort Dizziness / near-syncope Echocardiographic Criteria (Suggestive of PH / CTEPH) 1. Elevated pulmonary pressures 2. Right ventricular (RV) abnormalities 3. RV pressure overload signs 4. Right atrial enlargement 5. Indirect supportive signs: Dilated pulmonary artery

Secondary outcomes

• Occurence of intracranial hemorrhage [at the sooner of discharge or 7 days after the randomization]: Intracranial hemorrhage: Any bleeding involving the brain parenchyma, ventricular system, or subarachnoid, subdural, or epidural regions as identified by CT scan or MRI regardless of symptoms.
• Major bleeding according to the ISTH definition in non-surgical subjects [at the sooner of discharge or 7 days after the randomization]: Major bleeding according to the ISTH definition in non-surgical subjects includes 1. Fatal bleeding, AND/OR 2. Symptomatic bleeding in a critical area or organ, such as intracranial, intraspinal, intraocular, retroperitoneal, intraarticular or pericardial, or intramuscular with compartment syndrome, AND/OR 3. Bleeding causing a fall in hemoglobin level of ≥2 g/dL (1.24 mmol/L) or leading to transfusion of ≥2 units of whole blood or red cells
• Clinical deterioration and escalation to a bailout therapy [at the sooner of discharge or 7 days after the randomization]: Clinical deterioration AND/OR escalation to a bailout therapy in a. Clinical deterioration: defined by documented objective hemodynamic or respiratory worsening that is not present at the time of enrollment, including one or more of the following: i. Hypotension with SBP <90 mmHg lasting at least 30 minutes, unresponsive to fluid resuscitation, and requiring the addition of, or increased dose of, vasopressors. ii. Fall in SBP by ≥40 mmHg lasting at least 30 minutes and accompanied end organ hypoperfusion. iii. Cardiac arrest requiring cardiopulmonary resuscitation. iv. Bradycardia lasting >10 minutes, accompanied by hypotension and requiring pharmacologic intervention or insertion of a pacemaker. v. Ventricular tachycardia or fibrillation requiring pharmacologic intervention or defibrillation. vi. Requirement for an increase in fraction of inspired oxygen requirements ≥0.20, lasting longer than 30 minutes. vii. Need for intubation in a previously non-intubated patient.

Sex: All, ages: 18 Years to 80 Years

Inclusion Criteria:

* Age 18-80 years old.
* Clinical signs and symptoms consistent with acute PE with duration of 14 days or less.
* Objectively confirmed acute PE, based on CTPA imaging showing a filling defect in at least one main or proximal lobar pulmonary artery.
* Category E patients according to AHA recent guidelines for management of P.E including patients with cardiopulmonary failure states (either cardiac arrest, refractory cardiogenic shock or recurrent or persistent hypotension with cardiogenic shock).
* Category D patients (i.e patients with incipient cardiopulmonary failure) including normotensive shock with marker of decreased perfusion or end-organ dysfunction (eg, acute ischemic kidney injury, persistently elevated lactate) accompanied by transient hypotension and patients with transient or recurrent hypotension (including relative hypotension compared with the patient's baseline blood pressure) that is short-lived or responds to volume expansion and not accompanied by any signs of reduced perfusion or end-organ dysfunction.
* Category C2,C3 patients with symptomatic disease with increased risk of adverse outcomes by validated severity index and either abnormal RV or abnormal cardiac biomarkers or both.
* Femoral access deemed suitable for mechanical thrombectomy.
* Informed consent is obtained from either the patient or legally authorized representative.

Exclusion Criteria:

* Category A patients including asymptomatic and incidentally diagnosed PE cases.
* Category B patients with symptomatic acute PE and low risk of adverse outcomes by validated severity indices.
* Category C1 patients with symptomatic disease with increased risk of adverse outcomes by validated severity index with normal RV and normal cardiac biomarkers.
* History or imaging findings consistent with CTEPH or CTEPD diagnosis.
* Any known contraindication to anticoagulation including allergy, hypersensitivity, or heparin induced thrombocytopenia.
* Contraindication or sensitivity to iodinated intravascular contrast that cannot be adequately premedicated.
* Active bleeding or disorders contraindicating anticoagulant therapy.
* Platelets <50,000/µL.

• Ahmed A Abdelrady, Master of science, Principal investigator, Assiut University