SCCM Resource Library-Mechanical Thrombectomy Improves Cardiac Index in Pulmonary Embolism Patients in Subclinical Shock

Video Transcription

My name is Dr. Meena Lennox-Hill, per team. I'll be discussing today our research in mechanical thrombectomy improves cardiac  index in pulmonary embolism patients in subclinical shock. I'm a medical consultant for Inari Medical. Introduction.  The goal of risk stratification in pulmonary embolism is to identify a subset of patients who are at high risk for mortality and hemodynamic decompensation.  As we are aware, there's some limitation in the risk stratification scores that are available to us. Most of our patients will present in a hemodynamic, no more intensive state.  However, research showed us that there is a subset of patients who are hemodynamically stable or in a subclinical state of shock identified as a low cardiac index of two or  less, and the percentage is about 30%. So the objective of our study is to assess the prevalence of low cardiac index in patient  risk stratified using common schemes and to assess the immediate on table cardiac index changes in patient undergoing mechanical thrombectomy.  We use three common stratification schemes, ESC, simplified PESI score and ABOVA score. Each scheme use different components for risk stratification shown in the table below.  For each scheme, patient was split into two groups. We're calling them low risk and high risk for the sake of the analysis in this presentation. Slash baseline characteristics.  Patients enrolled in the FLASH study, which stands for Floater-Triever All Common Registry for Patient Safety and Hemodynamics.  The FLASH is a multicenter registry evaluating percutaneous mechanical thrombectomy outcomes using the Floater-Triever system.  And the table presented demographics with important take home messages about 40% of the patient had contraindication to lytics.  High risk stratification. This is the break of the first 250 patients enrolled in the FLASH study.  And you can see they're broken down into lower and higher risk group for each stratification scheme.  Although the goal of each scheme is similar, the risk stratification result varied quite a bit from each demonstrated by the results here.  As you see, the ESC identified 6.4% at a high risk compared to 84% in the simplified PESI score and 36% in the BOVA score.  Here we are looking at the proportion of patients in the lower risk tiers for each score will have a low baseline cardiac index.  But an average of 20% of patients with PE in each of the low risk tiers have a low cardiac index prior to thrombectomy, regardless of risk stratification method used.  These patients are in a subclinical shock despite appearing stable and may be at risk for hemodynamic deterioration.  It is hard to predict which apparently stable patients are going to deteriorate. The Flu Retriever System is a purpose-built percutaneous mechanical thrombectomy system.  As illustrated on the graph below, it's designed to rapidly extract thrombus for on-table hemodynamic restoration without the need for thrombolytics.  And as indicated before, about 40% of the patient will have contraindication for lytics. This procedure is done under local anesthesia using the lower extremity venous system.  On-the-table cardiac index can be evaluated immediately before and post-thrombectomy with the Flu Retriever System in a large flash cohort study.  The table below are the interim results on the first 500 flash patients. Here are some of the key procedure results in Lens Sustain.  In regard to axis site, the femoral vein was used exclusively in 99% of the cases. Side complication incidence was 0.4%. Two patients had hematoma at the puncture site.  Estimated device time was 43 minutes. Estimated blood loss was 260 ml. In about 3.8% of cases, adjuvant therapy were used. 16 patients had catheter-directed thrombolytics.  And two patients had adjuvant therapies unrelated to the PE treatment. Hospital average length of stay was 3 days.  Most of the patients did not require overnight ICU stay after the procedures. 63% of the patients did not require ICU.  The incidence of 48-hour major adverse event, which was the primary endpoint, was 1.4%. There was zero device-related deaths. There were six major bleeding.  None of them were intracranial hemorrhage. There was one procedure-related major adverse event. The patient clinically deteriorated, but that was not related to the device.  This is the most important slide and also the home take message. This shows the impact of the mechanical thrombectomy on the cardiac index.  Here we show the improvement in the cardiac index immediately after the thrombectomy. On the graph on the left side, there was no change in the cardiac index in the cohort group.  On the other hand, in the patient who presented with low cardiac index, the graph on the right hand side shows improvement in the cardiac index after mechanical thrombectomy.  There was improvement in the cardiac index on the table by 18% and that reaches statistically significant value with a P-value of less than 0.0001.  And these are the patients who were identified with low cardiac index and at risk of hemodynamic decompensation.  The important point is that I would like to highlight here that the changes occurred on  the table versus hours, days, as you can see from the literature in regard to use of thrombolytic treatment in the treatment of some massive pulmonary emboli.  In conclusion to our talk and the home take message, I would like to highlight three important points.  The first point is, regardless of the risk stratification scheme used, on an average about 20% of the patients who were labeled to be hemodynamically stable and of low risk  tiers had actually a low cardiac index below 2. A subset of patients appeared to be at risk for imminent hemodynamic collapse.  The second point is, patients with low cardiac index, that subset of patients experienced significant improvement on the table, and I emphasize on the table, hemodynamic improvement  in their cardiac index with mechanical thrombectomy via the flow retriever. And their average cardiac index reached nearly normal levels.  The third and the final point, the results from our study suggest a substantial portion  of hemodynamically stable patients with pulmonary emboli may be at risk of a hemodynamic collapse and a state of subclinical shock.  That subset of patients may benefit from mechanical thrombectomy and improvement in the hemodynamics and that ultimately will be translated into improvement and their outcome.  I acknowledge all the centers participating in the FLASH study and their primary investigator and thank you.

Video Summary

Dr. Meena Lennox-Hill discusses research that shows mechanical thrombectomy improves cardiac index in pulmonary embolism patients with subclinical shock. Risk stratification in pulmonary embolism aims to identify high-risk patients, but current scores have limitations. The study analyzes the prevalence of low cardiac index in risk-stratified patients and assesses the immediate cardiac index changes during mechanical thrombectomy. The study uses three risk stratification schemes and finds that about 20% of hemodynamically stable, low-risk patients have a low cardiac index. The study also shows that patients with low cardiac index experience significant improvement in cardiac index after mechanical thrombectomy. These findings suggest that a subset of hemodynamically stable patients may benefit from this treatment.

Asset Subtitle

Cardiovascular, Pulmonary, 2022

Asset Caption

INTRODUCTION/HYPOTHESIS: Most pulmonary embolism (PE) patients are normotensive, and PE risk stratification schemes have limitations in identifying the subset of these normotensive patients who are at risk for sudden decompensation. Even if patients present as hemodynamically stable, they may be in subclinical shock due to low cardiac index (CI). The objective of this research is to assess immediate changes in CI in risk-stratified PE patients undergoing percutaneous mechanical thrombectomy as frontline therapy. METHODS: PE patients were enrolled in FLASH, a prospective registry evaluating the safety and effectiveness of mechanical thrombectomy with the FlowTriever System (Inari Medical, Irvine, CA; NCT03761173). Patients were risk-stratified using current ESC guidelines, simplified Pulmonary Embolism Severity Index (sPESI), and Bova score. Immediately prior to and following thrombectomy, CI was measured via right heart catheterization. At baseline, patients were grouped into low-CI (< 2 l/min/m2) and normal-CI (≥ 2 l/min/m2) cohorts, and the prevalence of patients with low CI was determined for each risk category. Pre- vs. post-thrombectomy changes in CI were then compared within the low-CI and normal-CI cohorts. RESULTS: Despite being in lower risk categories, 20% of patients with ESC intermediate-risk classification, 22% of patients with sPESI = 0, and 20% of patients with Stage I or II Bova scores had low CI at baseline. Among all patients in the low-CI cohort, CI increased significantly on-table after thrombectomy by an average of 13.3% from 1.7±0.2 to 1.9±0.4 l/min/m2 (p=0.005; Nf42). Patients who already had normal CI at baseline did not experience a significant change in CI (2.9±0.9 vs. 3.0±1.9 l/min/m2, p=0.207; Nf160). CONCLUSIONS: Regardless of the specific risk stratification scheme used, approximately one-fifth of all patients in the lower-risk tiers within each scheme had low CI at baseline. These patients experienced a significant on-table improvement in CI immediately following mechanical thrombectomy, with the average post-treatment CI almost reaching physiologically normal levels. These data suggest that a substantial proportion of hemodynamically stable PE patients may be in subclinical shock, and these same patients may realize an immediate improvement in CI following mechanical thrombectomy.

Meta Tag

Content Type Presentation

Knowledge Area Cardiovascular

Knowledge Area Pulmonary

Knowledge Level Intermediate

Knowledge Level Advanced

Learning Pathway Cardiothoracic Critical Care

Membership Level Select

Tag Shock

Tag Pulmonary Embolism

Tag Hemodynamic Monitoring

Tag Pulmonary Circulation

Tag Thromboembolism

Tag Cardiothoracic Critical Care

Year 2022

Keywords

mechanical thrombectomy

cardiac index

pulmonary embolism

risk stratification

subclinical shock

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