Percutaneous thrombectomy in patients with massive and very high-risk submassive acute pulmonary embolism

Comparison of Safety and Efficacy of Aspiration Thrombectomy and Ultrasound Accelerated Thrombolysis for Management of Pulmonary Embolism: A Systematic Review and Meta-Analysis

PURPOSE

To compare the safety and efficacy of mechanical thrombectomy (MT) and ultrasound-accelerated thrombolysis (USAT) in pulmonary embolism (PE) management by performing a systematic review of the literature.

MATERIALS AND METHODS

The PubMed database was searched to identify articles on Inari's FlowTriever and Penumbra's Indigo mechanical thrombectomy devices (Group A) and the Ekos Endovascular system (Group B). Outcomes variables analyzed include pre- and post-procedure RV/LV ratio, pre- and post-procedure pulmonary artery pressure, hospital length of stay, technical success, specific complications, and mortality rate. Mean values were calculated using the weighted mean approach. RevMan Version 5.4 (Cochrane Collaboration) was used to perform the meta-analysis for this study. Cochrane Collaboration's Risk of Bias (RoB 2.0) approach was used to perform a quality assessment of the included articles in order to verify the validity and reliability of the research.

RESULTS

27 studies were in Group A and 28 studies pertained to Group B. There were 1662 patients in Group A and 1273 patients in Group B. Both groups had similar technical success (99.6% vs 99.4%). Thrombectomy showed longer mean procedure time (73.03 ± 14.57 min vs 47.35 ± 3.15 min), lower mean blood loss (325.20 ± 69.15 mL vs 423.05 ± 64.95 mL), shorter mean ICU stay (2.35 ± 1.64 days vs 3.22 ± 1.27 days), and shorter mean overall hospital stay (6.94 ± 4.38 days vs 7.23 ± 2.31 days). EKOS showed greater mean change in Miller Index (9.05 ± 3.35 vs 4.91 ± 3.70) and greater mean change in pulmonary artery pressure (14.17 ± 6.35 mmHg vs 8.11 ± 4.39 mmHg).

CONCLUSION

Ultrasound accelerated thrombolysis and percutaneous mechanical thrombectomy are effective therapies for pulmonary embolism with comparable clinical outcomes.

Safety and efficacy of catheter-directed thrombectomy without thrombolysis in acute pulmonary embolism: A systematic review and meta-analysis

BACKGROUND

This meta-analysis aims to investigate the safety and efficacy of catheter-directed thrombectomy (CDT) without using adjunct thrombolysis as reperfusion therapy to manage intermediate and high-risk pulmonary embolism (PE).

METHODS

A literature search of Ovid MEDLINE, Embase, CiNAHL, Cochrane Library, and Web of Science was conducted from inception to January 2024. Eligible studies reported more than 10 patients treated for acute PE with catheter-directed thrombectomy only, who were over 18 years of age. Primary endpoints were major bleeding, in-hospital mortality, and hemodynamic changes.

RESULTS

Eighteen studies (n = 803) were included for quantitative analysis. The pooled estimate of incidences of in-hospital mortality and major bleeding was 1.8 % (95 % CI 0.009, 0.027) and 2.1 % (95 % CI 0.011, 0.031) respectively. A pooled estimate reported a post-procedural increase in oxygen saturation and systolic blood pressure by 8.96 % (95 % CI: 3.54, 14.38) and 15.02 mmHg (95 % CI 6.35, 23.69) respectively. Post-procedural mean pulmonary artery pressure, right ventricle/left ventricle (RV/LV) ratio, and Miller score were reduced by 10.30 mmHg (95 % CI -14.94, -5.66), 0.29 (95 % CI -0.50, -0.08) and 8.09 (95 % CI -10.70, -5.47) respectively.

CONCLUSION

CDT without adjunctive thrombolysis may lead to improvements in hemodynamic outcomes and exhibits favorable safety profiles. This meta-analysis provides a rationale for lowering the threshold for considering this technique, and ongoing randomized trials will further advance the field to determine optimal managment strategies for intermediate and high-risk acute PE.

Mechanical clot disruption during pulmonary thromboembolectomy is safe: A propensity score-matched analysis

PURPOSE

Aspiration thromboembolectomy is effective for treatment of high and intermediate-high risk pulmonary emboli (PE) but can be challenging when organized thrombus is present. Maceration using an expandable nitinol disk may be useful in these situations, but its safety has not been determined. The purpose of this study was to retrospectively assess the safety of this device when applied in the pulmonary vasculature, using a propensity-score matched group for comparison.

MATERIALS AND METHODS

Inclusion criteria consisted of patients who underwent PE thromboembolectomy within a single healthcare system between December 2020 and December 2022 and subsequently underwent suction thromboembolectomy in which the nitinol disk was used. A comparator group was generated from the remaining patients who underwent conventional PE thromboembolectomy by performing one-to-one propensity-score matching based on age, PE risk category, and sPESI score.

RESULTS

Out of a total of 164 patients who underwent pulmonary thromboembolectomy during the study period, the disk was utilized in 28. The disk was used in the left pulmonary artery in nearly 80 % of patients and in the right pulmonary artery in less than 40 %. Initial, final, and change in mean pulmonary artery pressures were not significantly different between groups. Similarly, mean duration of hospitalization, number of complications, and 30-day mortality rate did not differ.

CONCLUSION

Use of a nitinol disk during pulmonary thromboembolectomy is safe despite administration of anticoagulation. Clinical effectiveness remains to be determined.

VA-ECOM assisted percutaneous mechanical thrombectomy treatment high-risk pulmonary embolism

Background

Percutaneous mechanical thrombectomy (PMT) is increasingly used in the treatment of intermediate and high-risk acute pulmonary embolism (PE), and the treatment of high-risk PE with the aid of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has also been reported. However, there are few reports of VA-ECOM-assisted PMT in the treatment of high-risk PE. The purpose of this study is to summarize the data of 11 patients with high-risk PE treated with VA-ECMO assisted PMT, and propose feasible treatment methods for such patients.

Methods

This multicenter retrospective study included patients with acute high-risk PE who were treated with VA-ECMO-assisted PMT from January 2021 to June 2024. The analysis focused on the right/left ventricle ratio, biomarkers, and pulmonary artery pressure before and after the VA-ECMO-assisted PMT treatment.

Results

All 11 high-risk PE patients suffered cardiac arrest before treatment, computered tomograhy pulmonary angiography (CTPA) confirmed the diagnosis of PE, and all patients received VA-ECMO-assisted PMT therapy. The median age of the 11 patients was 54 years (range 18-72), the median duration of ECMO was 4.48 days (range 1.04-18.02), and the mean hospitalization time was 21 days (range 14-112). All patients received percutaneous thrombectomy, achieving a 100% technical success rate. The mortality rate was 27.3% during the 90-day follow-up. The 12-month mortality rate was 36.4%.

Conclusion

VA-ECMO-assisted PMT technology can rapidly improve pulmonary hemodynamics while maintaining stable blood flow, thereby reducing in-hospital mortality in high-risk patients with pulmonary embolism complicated by cardiac arrest.

Large-bore Aspiration Thrombectomy with the FlowTriever System for the Treatment of Pulmonary Embolism: A Large Single-Center Retrospective Analysis

PURPOSE

Evaluate the outcomes of patients undergoing large-bore aspiration thrombectomy for the treatment of pulmonary embolism at a large university medical center.

MATERIALS AND METHODS

All patients treated for pulmonary embolism with the FlowTriever System (Inari Medical, Irvine, CA) between September 2019 and January 2023 were retrospectively analyzed. The primary safety and effectiveness outcomes included 7- and 30-day all-cause mortality, major bleeding, procedure-associated clinical decompensation, pulmonary vascular or cardiac injury, and pulmonary artery pressure reduction. Additional outcomes included technical success (completing thrombectomy with the device as intended), changes in hemodynamics and supplemental oxygen requirements, and postprocedural intensive care unit stay.

RESULTS

A total of 286 patients were identified. The mean age was 60.5 years, and 90.9% of patients presented with intermediate-risk pulmonary embolism. Technical success was achieved in 96.9% (n = 277) of cases. The average reduction in mean pulmonary arterial pressure was 6.8 mmHg, from 28.7 ± 9.0 to 21.9 ± 8.0 mmHg (p < 0.0001). Two major bleeds (0.7%), 2 pulmonary vascular injuries (0.7%), and 4 (1.4%) procedure-associated decompensations were reported, but no device-related deaths occurred. The mean post-procedure intensive care unit stay was 2.0 ± 4.1 days, and 49.3% of patients had no postprocedural intensive care unit admittance. The overall 7-day and 30-day all-cause mortality rates were 2.4% and 6.7%, respectively, with a 30-day pulmonary embolism-related mortality rate of 3.5%.

CONCLUSION

This non-industry-sponsored single-center analysis of large-bore aspiration thrombectomy in a large population corroborates the findings of other studies and confirms that this approach is safe and effective for the treatment high- and intermediate-risk pulmonary embolism.

LEVEL OF EVIDENCE IV

Retrospective observational study.

Episode Care Costs Following Catheter-Directed Reperfusion Therapies for Pulmonary Embolism: A Literature-Based Comparative Cohort Analysis

This analysis aimed to estimate 30-day episode care costs associated with 3 contemporary endovascular therapies indicated for treatment of pulmonary embolism (PE). Systematic literature review was used to identify clinical research reporting costs associated with invasive PE care and outcomes for ultrasound-accelerated thrombolysis (USAT), continuous-aspiration mechanical thrombectomy (CAMT), and volume-controlled-aspiration mechanical thrombectomy (VAMT). Total episode variable care costs were defined as the sum of device costs, variable acute care costs, and contingent costs. Variable acute care costs were estimated using methodology sensitive to periprocedural and postprocedural resource allocation unique to the 3 therapies. Contingent costs included expenses for thrombolytics, postprocedure bleeding events, and readmissions through 30 days. Through February 28, 2023, 70 sources were identified and used to inform estimates of 30-day total episode variable costs. Device costs for USAT, CAMT, and VAMT were the most expensive single component of total episode variable costs, estimated at $5,965, $10,279, and $11,901, respectively. Costs associated with catheterization suite utilization, intensive care, and hospital length of stay, along with contingent costs, were important drivers of total episode costs. Total episode variable care costs through 30 days were $19,146, $20,938, and $17,290 for USAT, CAMT, and VAMT, respectively. In conclusion, estimated total episode care costs after invasive treatment for PE are heavily influenced by device expense, in-hospital care, and postacute care complications. Regardless of device cost, strategies that avoid thrombolytics, reduce the need for intensive care unit care, shorten length of stay, and reduce postprocedure bleeding and 30-day readmissions contributed to the lowest episode costs.

The Current Evidence of Pulmonary Embolism Response Teams and Their Role in Future

Acute pulmonary embolism (PE) remains a critical medical condition requiring prompt and accurate management. The introduction and growing significance of pulmonary embolism response teams (PERT), also termed EXPERT-PE teams, signify a paradigm shift toward a collaborative, multidisciplinary approach in managing this complex entity. As the understanding of acute PE continues to evolve, PERTs stand as a linkage of optimized care, offering personalized and evidence-based management strategies for patients afflicted by this life-threatening condition. The evolving role of PERTs globally is evident in their increasing integration into the standard care pathways for acute PE. These teams have demonstrated benefits such as reducing time to diagnosis and treatment initiation, optimizing resource utilization, and improving patient outcomes.

Catheter Interventions for Pulmonary Embolism: Mechanical Thrombectomy Versus Thrombolytics

Pulmonary embolism is a debilitating and potentially life-threatening disease characterized by high mortality and long-term adverse outcomes. Traditional treatment options are fraught with serious bleeding risks and incomplete thrombus removal, necessitating the development of innovative treatment strategies. While new interventional approaches offer promising potential for improved outcomes with fewer serious complications, their rapid development and need for more comparative clinical evidence makes it challenging for physicians to select the optimal treatment for each patient among the many options. This review summarizes the current published clinical data for both traditional treatments and more recent interventional approaches indicated for pulmonary embolism. While published studies thus far suggest that these newer interventional devices offer safe and effective options, more data is needed to understand their impact relative to the standard of care. The studies in progress that are anticipated to provide needed evidence are reviewed here since they will be critical for helping physicians make informed treatment choices and potentially driving necessary guideline changes.

Electrocardiographic Changes after Endovascular Mechanical Thrombectomy in a Patient with Pulmonary Embolism-A Case Report and Literature Review

Background: Pulmonary embolism (PE) is a common disease with an annual incidence of about 1/1000 persons. About every sixth patient dies within the first 30 days after diagnosis. The electrocardiogram (ECG) is one of the first diagnostic tests performed, and is able to confirm the suspicion of PE with typical electrocardiographic signs. Some ECG signs and their regression are also prognostically relevant. Endovascular mechanical thrombectomy is one option for PE treatment, and aims to relieve right heart strain immediately. The first studies on endovascular mechanical thrombectomy using a dedicated device (FlowTriever System, Inari Medical, Irvine, CA, USA) yielded promising results. Methods: In the following, we report the case of a 66-year-old male patient who presented with New York Heart Association III dyspnea in our emergency department. Among typical clinical and laboratory results, he displayed very impressive electrocardiographic and radiological findings at the time of PE diagnosis. Results: After endovascular mechanical thrombectomy, the patient's complaints and pulmonary hemodynamics improved remarkably. In contrast, the ECG worsened paradoxically 18 h after intervention. Nevertheless, control echocardiography 4 days after the intervention no longer showed any signs of right heart strain, and dyspnea had disappeared completely. At a 4-month follow-up visit, the patient presented as completely symptom-free with a high quality of life. His ECG and echocardiography were normal and excluded recurrent right heart strain. Conclusions: Overall, the patient benefitted remarkably from endovascular mechanical thrombectomy, resulting in an almost complete resolution of electrocardiographic PE signs at the 4-month follow-up after exhibiting multiple typical electrocardiographic PE signs at time of diagnosis and initial electrocardiographic worsening 18 h post successful intervention.

Saddle Pulmonary Embolus Treated With Bilateral Emergent Aspiration Pulmonary Thrombectomy

A 77 year old man with recurrent lower extremity thrombosis presented with acute onset shortness of breath and new onset hypoxemia three days after prostatectomy for adenocarcinoma of the prostate. He had been off anticoagulation during the perioperative period. In addition to his new diagnosis of prostate cancer he also had a remote history of treated non-invasive melanoma. Based on this presentation he was at high risk of developing thromboembolic disease. Computed tomography angiogram (CTA) of his chest confirmed a large saddle pulmonary embolus, echocardiogram was positive for new right ventricular wall motion dyskinesis and lower extremity ultrasound revealed bilateral acute and chronic deep vein thrombosis. Given his high bleeding risk, hypoxia and elevated troponin I, he underwent emergent successful aspiration pulmonary thrombectomy. This case is of interest to hospitalists and intesivists as it provides an overview of the current invasive management of pulmonary embolus in the acute setting when systemic anticoagulation is contraindicated. Emergent Aspiration Pulmonary Thrombectomy can restore pulmonary artery flow and cardiopulmonary hemodynamics. A collaborative team based approach that involves the emergency department, intensive care unit, interventional teams and hospitalists is favored.

A meta-analysis of outcomes of aspiration thrombectomy for high and intermediate-risk pulmonary embolism

BACKGROUND

Aspiration thrombectomy has gained popularity in patients with massive and sub-massive pulmonary embolism (PE) and having contraindications to thrombolysis.

METHODS

A meta-analysis was conducted including studies on aspiration thrombectomy in patients with high-risk and intermediate-risk PE. The pooled odds ratio for efficacy parameters, including change in heart rate, blood pressure and right ventricle/left ventricle (RV/LV) ratio, and safety parameters including major bleeding and stroke, was calculated using a random effects model.

RESULTS

The meta-analysis of 24 selected studies revealed that intermediate and high-risk pulmonary embolism (PE) patients demonstrated significant improvements: modified Miller score odds ratio of 10.60, mean pulmonary artery pressure reduction by 0.04 mm Hg, and an overall all-cause mortality odds ratio of 0.10. Considerable heterogeneity was observed in various outcomes.

CONCLUSION

Aspiration thrombectomy has success rates in both high-risk and intermediate-risk PE, however, procedural risks, including bleeding, must be anticipated.

Mechanical Thrombectomy for High-Risk Pulmonary Embolism: Insights From the US Cohort of the FLASH Registry

Background

Acute mortality for high-risk, or massive, pulmonary embolism (PE) is almost 30% even when treated using advanced therapies. This analysis assessed the safety and effectiveness of mechanical thrombectomy (MT) for high-risk PE.

Methods

The prospective, multicenter FlowTriever All-comer Registry for Patient Safety and Hemodynamics (FLASH) study is designed to evaluate real-world PE patient outcomes after MT with the FlowTriever System (Inari Medical). In this study, acute outcomes through 30 days were evaluated for the subset of patients with high-risk PE as determined by the sites and following European Society of Cardiology guidelines. An independent medical monitor adjudicated adverse events (AEs), including major AEs: device-related mortality, major bleeding, or intraprocedural device-related or procedure-related AEs.

Results

Of the 799 patients in the US cohort, 63 (7.9%) were diagnosed with high-risk PE; 30 (47.6%) patients showed a systolic blood pressure <90 mm Hg, 29 (46.0%) required vasopressors, and 4 (6.3%) experienced cardiac arrest. The mean age of patients with high-risk PE was 59.4 ± 15.6 years, and 34 (54.0%) were women. At baseline, 45 (72.6%) patients were tachycardic, 18 (54.5%) showed elevated lactate levels of ≥2.5 mM, and 21 (42.9%) demonstrated depressed cardiac index of <2 L/min/m2. Immediately after MT, heart rate improved to 93.5 ± 17.9 bpm. Twenty-five (42.4%) patients did not require an overnight stay in the intensive care unit, and no mortalities or major AEs occurred through 48 hours. Moreover, no mortalities occurred in 61 (96.8%) patients followed up through the 30-day visit.

Conclusions

In this cohort of 63 patients with high-risk PE, MT was safe and effective, with no acute mortalities reported. Further prospective data are needed in this population.

Randomized controlled trial of mechanical thrombectomy vs catheter-directed thrombolysis for acute hemodynamically stable pulmonary embolism: Rationale and design of the PEERLESS study

BACKGROUND

The identification of hemodynamically stable pulmonary embolism (PE) patients who may benefit from advanced treatment beyond anticoagulation is unclear. However, when intervention is deemed necessary by the PE patient's care team, data to select the most advantageous interventional treatment option are lacking. Limiting factors include major bleeding risks with systemic and locally delivered thrombolytics and the overall lack of randomized controlled trial (RCT) data for interventional treatment strategies. Considering the expansion of the pulmonary embolism response team (PERT) model, corresponding rise in interventional treatment, and number of thrombolytic and nonthrombolytic catheter-directed devices coming to market, robust evidence is needed to identify the safest and most effective interventional option for patients.

METHODS

The PEERLESS study (ClinicalTrials.gov identifier: NCT05111613) is a currently enrolling multinational RCT comparing large-bore mechanical thrombectomy (MT) with the FlowTriever System (Inari Medical, Irvine, CA) vs catheter-directed thrombolysis (CDT). A total of 550 hemodynamically stable PE patients with right ventricular (RV) dysfunction and additional clinical risk factors will undergo 1:1 randomization. Up to 150 additional patients with absolute thrombolytic contraindications may be enrolled into a nonrandomized MT cohort for separate analysis. The primary end point will be assessed at hospital discharge or 7 days post procedure, whichever is sooner, and is a composite of the following clinical outcomes constructed as a hierarchal win ratio: (1) all-cause mortality, (2) intracranial hemorrhage, (3) major bleeding, (4) clinical deterioration and/or escalation to bailout, and (5) intensive care unit admission and length of stay. The first 4 components of the win ratio will be adjudicated by a Clinical Events Committee, and all components will be assessed individually as secondary end points. Other key secondary end points include all-cause mortality and readmission within 30 days of procedure and device- and drug-related serious adverse events through the 30-day visit.

IMPLICATIONS

PEERLESS is the first RCT to compare 2 different interventional treatment strategies for hemodynamically stable PE and results will inform strategy selection after the physician or PERT determines advanced therapy is warranted.

Interventional therapies for pulmonary embolism

Pulmonary embolism (PE) is the leading cause of in-hospital death and the third most frequent cause of cardiovascular death. The clinical presentation of PE is variable, and choosing the appropriate treatment for individual patients can be challenging. Traditionally, treatment of PE has involved a choice of anticoagulation, thrombolysis or surgery; however, a range of percutaneous interventional technologies have been developed that are under investigation in patients with intermediate-high-risk or high-risk PE. These interventional technologies include catheter-directed thrombolysis (with or without ultrasound assistance), aspiration thrombectomy and combinations of the aforementioned principles. These interventional treatment options might lead to a more rapid improvement in right ventricular function and pulmonary and/or systemic haemodynamics in particular patients. However, evidence from randomized controlled trials on the safety and efficacy of these interventions compared with conservative therapies is lacking. In this Review, we discuss the underlying pathophysiology of PE, provide assistance with decision-making on patient selection and critically appraise the available clinical evidence on interventional, catheter-based approaches for PE treatment. Finally, we discuss future perspectives and unmet needs.

Outcomes in High-Risk Pulmonary Embolism Patients Undergoing FlowTriever Mechanical Thrombectomy or Other Contemporary Therapies: Results From the FLAME Study

BACKGROUND

Hemodynamically unstable high-risk, or massive, pulmonary embolism (PE) has a reported in-hospital mortality of over 25%. Systemic thrombolysis is the guideline-recommended treatment despite limited evidence. The FLAME study (FlowTriever for Acute Massive PE) was designed to generate evidence for interventional treatments in high-risk PE.

METHODS

The FLAME study was a prospective, multicenter, nonrandomized, parallel group, observational study of high-risk PE. Eligible patients were treated with FlowTriever mechanical thrombectomy (FlowTriever Arm) or with other contemporary therapies (Context Arm). The primary end point was an in-hospital composite of all-cause mortality, bailout to an alternate thrombus removal strategy, clinical deterioration, and major bleeding. This was compared in the FlowTriever Arm to a prespecified performance goal derived from a contemporary systematic review and meta-analysis.

RESULTS

A total of 53 patients were enrolled in the FlowTriever Arm and 61 in the Context Arm. Context Arm patients were primarily treated with systemic thrombolysis (68.9%) or anticoagulation alone (23.0%). The primary end point was reached in 9/53 (17.0%) FlowTriever Arm patients, significantly lower than the 32.0% performance goal (P<0.01). The primary end point was reached in 39/61 (63.9%) Context Arm patients. In-hospital mortality occurred in 1/53 (1.9%) patients in the FlowTriever Arm and in 18/61 (29.5%) patients in the Context Arm.

CONCLUSIONS

Among patients selected for mechanical thrombectomy with the FlowTriever System, a significantly lower associated rate of in-hospital adverse clinical outcomes was observed compared with a prespecified performance goal, primarily driven by low all-cause mortality of 1.9%.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04795167.

Interventional therapies in acute pulmonary embolus-current trends and future directions

Venous thromboembolic disease presenting with acute pulmonary embolus (PE) can be treated in a variety of ways from anticoagulation as an outpatient to surgical embolectomy with many new interventional therapies being developed. Mortality in these patients can be as high as 50% and many of these treatments are also considered to be high risk. Early involvement of a multidisciplinary team and patient risk stratification can aid management decisions in these complex patients who can suddenly deteriorate.In this review, we summarise the evidence behind new and developing interventional therapies in the treatment of high and intermediate-high risk PE including catheter-directed thrombolysis, pharmacomechanical thrombolysis, thromboaspiration and the growing role of extracorporeal membrane oxygenation in the stabilisation and management of this cohort of patients.

Cardiovascular collapse during mechanical thrombectomy for acute pulmonary embolism and the role of extracorporeal membrane oxygenation in patient rescue

BACKGROUND

Driven by the ability to avoid thrombolytics and provide a one stop procedure with immediate hemodynamic improvement, there has been a dramatic increase in the use of mechanical thrombectomy (MT) devices for the treatment of intermediate-to-high risk pulmonary embolism (PE). This study investigated the incidence and outcomes of cardiovascular collapse during MT procedures and demonstrates the role of extracorporeal membrane oxygenation (ECMO) in salvaging patients.

METHODS

This single-center retrospective review included patients with PE undergoing MT with the FlowTriever device between 2017 and 2022. Patients presenting periprocedural cardiac arrest were identified and their perioperative characteristics and postoperative outcomes were evaluated.

RESULTS

A total of 151 patients with a mean age of 64 ± 14 years who presented with intermediate-to-high risk PE received LBAT procedures during the study period. The simplified PE severity score was ≥1 in 83% of cases and the average RV/LV ratio was 1.6 ± 0.5, with and elevated troponin in 84%. Technical success was achieved in 98.7% and a significant decrease in pulmonary artery systolic pressure (PASP) was observed (37 mm Hg vs 56 mm Hg; P < .0001). Intraoperative cardiac arrest occurred in nine patients (6%). These patients were more likely to present PASP of ≥70 mm Hg (84% vs 14%; P < .001), were more hypotensive upon admission (systolic of 94 ± 14 mm Hg vs 119 ± 23 mm Hg; P = .004), presented lower oxygen saturation levels (87 ± 6% vs 92 ± 6%; P = .023) and were more likely to present with a history of recent surgery (67% vs 18%; P = .004). Four patients were rescued successfully with ECMO and their residual PE was subsequently removed before discharge by surgical embolectomy in two of the four cases and repeat MT in the other two. All five patients (3%) who did not receive ECMO support expired intraoperatively. The overall 30-day mortality was 8% with no death occurring in patients who were salvaged with ECMO.

CONCLUSIONS

Large-bore aspiration thrombectomy for acute PE is associated with favorable technical outcomes, but the concern for acute cardiac decompensation is non-negligible in patients presenting with high-risk features and a PASP of ≥70 mm Hg. ECMO can help to salvage some of these patients and should be considered in the treatment algorithms of patients deemed at high risk.

Catheter-Directed Thrombolysis or Catheter-Based Thrombectomy in Acute Pulmonary Embolism: Horses for Courses

Venous thromboembolism is a common disorder encompassing both pulmonary embolism (PE) and deep vein thrombosis (DVT). In the United States, up to 2 million people are diagnosed with DVT and 600,000 with PE annually. The purpose of this review is to discuss the indications and evidence for catheter-directed thrombolysis versus catheter-based thrombectomy.

Longer-Term Outcomes Following Mechanical Thrombectomy for Intermediate- and High-Risk Pulmonary Embolism: 6-Month FLASH Registry Results

Background

Mechanical thrombectomy provides rapid hemodynamic improvements after acute pulmonary embolism (PE), but long-term benefits are uncertain.

Methods

FlowTriever All-comer Registry for Patient Safety and Hemodynamics is a prospective, single-arm, multicenter registry of patients with acute PE treated with the FlowTriever System (Inari Medical). Six-month outcomes including modified Medical Research Council dyspnea scores (MMRCD), right ventricular (RV) function, 6-minute walk test distances, and PE quality-of-life scores (QoL) were assessed.

Results

In total, 799 patients were enrolled and 75% completed the study with a mean follow-up of 204 ± 46 days. Demographic characteristics included 54.1% men, mean age of 61.2 years, 77.1% intermediate-high-risk PE, and 8.0% high-risk PE. All-cause mortality was 4.6% at study completion. The proportion of patients with normal echocardiographic RV function increased from 15.1% at baseline to 95.1% at 6 months (P < .0001). MMRCD score improved from 3.0 at baseline to 0.0 at 6 months (P < .0001). 6-minute walk test distances increased from 180 m at 48 hours to 398 m at 6 months (P < .001). Median PE QoL total scores were 9.38 at 30 days and 4.85 at 6 months (P < .001). Prevalence of site-reported chronic thromboembolic pulmonary hypertension was 1.0% and chronic thromboembolic disease was 1.9%.

Conclusions

In this large diverse group of PE patients, 6-month all-cause mortality, chronic thromboembolic pulmonary hypertension, and chronic thromboembolic disease were low following thrombectomy with the FlowTriever system. Significant improvements in RV function, patient symptoms, exercise capacity, and QoL were observed at 6 months, suggesting that rapid extraction of thrombus may prevent long-term sequelae in patients with PE.

Unmet Needs and Future Direction for Pulmonary Embolism Interventions

Venous thromboembolism (VTE) usually develops in the deep veins of the extremities. Pulmonary embolism (PE) is a type of VTE that is most commonly (∼90%) caused by a thrombus that originates from the deep veins of the lower extremities. PE is the third most common cause of death after myocardial infarction and stroke. In this review, the authors investigate and discuss the risk stratification and definitions of the aforementioned categories of PE and further explore the management of acute PE along with the types of catheter-based treatment options and their efficacy.

Acute outcomes for the full US cohort of the FLASH mechanical thrombectomy registry in pulmonary embolism

BACKGROUND

Evidence supporting interventional pulmonary embolism (PE) treatment is needed.

AIMS

We aimed to evaluate the acute safety and effectiveness of mechanical thrombectomy for intermediate- and high-risk PE in a large real-world population.

METHODS

FLASH is a multicentre, prospective registry enrolling up to 1,000 US and European PE patients treated with mechanical thrombectomy using the FlowTriever System. The primary safety endpoint is a major adverse event composite including device-related death and major bleeding at 48 hours, and intraprocedural adverse events. Acute mortality and 48-hour outcomes are reported. Multivariate regression analysed characteristics associated with pulmonary artery pressure and dyspnoea improvement.

RESULTS

Among 800 patients in the full US cohort, 76.7% had intermediate-high risk PE, 7.9% had high-risk PE, and 32.1% had thrombolytic contraindications. Major adverse events occurred in 1.8% of patients. All-cause mortality was 0.3% at 48-hour follow-up and 0.8% at 30-day follow-up, with no device-related deaths. Immediate haemodynamic improvements included a 7.6 mmHg mean drop in mean pulmonary artery pressure (-23.0%; p<0.0001) and a 0.3 L/min/m2 mean increase in cardiac index (18.9%; p<0.0001) in patients with depressed baseline values. Most patients (62.6%) had no overnight intensive care unit stay post-procedure. At 48 hours, the echocardiographic right ventricle/left ventricle ratio decreased from 1.23±0.36 to 0.98±0.31 (p<0.0001 for paired values) and patients with severe dyspnoea decreased from 66.5% to 15.6% (p<0.0001).  Conclusions: Mechanical thrombectomy with the FlowTriever System demonstrates a favourable safety profile, improvements in haemodynamics and functional outcomes, and low 30-day mortality for intermediate- and high-risk PE.

Mechanical aspiration thrombectomy for the treatment of pulmonary embolism: A systematic review and meta-analysis

INTRODUCTION

There are no randomized trials studying the outcomes of mechanical aspiration thrombectomy (MAT) for management of pulmonary embolism (PE).

METHODS

We performed a systematic review and meta-analysis of existing literature to evaluate the safety and efficacy of MAT in the setting of PE. Inclusion criteria were as follows: studies reporting more than five patients, study involved MAT, and reported clinical outcomes and pulmonary artery pressures. Studies were excluded if they failed to separate thrombectomy data from catheter-directed thrombolysis data. Databases searched include PubMed, EMBASE, Web of Science until April, 2021.

RESULTS

Fourteen case series were identified, consisting of 516 total patients (mean age 58.4 ± 13.6 years). Three studies had only high-risk PE, two studies had only intermediate-risk PE, and the remaining nine studies had a combination of both high-risk and intermediate-risk PE. Six studies used the Inari FlowTriever device, five studies used the Indigo Aspiration system, and the remaining three studies used the Rotarex or Aspirex suction thrombectomy system. Four total studies employed thrombolytics in a patient-specific manner, with seven receiving local lysis and 17 receiving systemic lysis, and 40 receiving both. A random-effects meta-analyses of proportions of in-hospital mortality, major bleeding, technical success, and clinical success were calculated, which yielded estimate pooled percentages [95% CI] of 3.6% [0.7%, 7.9%], 0.5% [0.0%, 1.8%], 97.1% [94.8%, 98.4%], and 90.7% [85.5%, 94.3%].

CONCLUSION

There is significant heterogeneity in clinical, physiologic, and angiographic data in the currently available data on MAT. RCTs with consistent parameters and outcomes measures are still needed.

Contemporary Management of Acute Pulmonary Embolism: Evolution of Catheter-based Therapy

Acute pulmonary embolism (PE) affects more than 100 000 people in the United States annually and is the third leading cardiovascular cause of death. The standard management for PE is systemic anticoagulation therapy. However, a subset of patients experience hemodynamic decompensation, despite conservative measures. Traditionally, these patients have been treated with systemic administration of thrombolytic agents or open cardiac surgery, although attempts at endovascular treatment have a long history that dates back to the 1960s. The technology for catheter-based therapy for acute PE is rapidly evolving, with multiple devices approved over the past decade. Currently available devices fall into two broad categories of treatment methods: catheter-directed thrombolysis and percutaneous suction thrombectomy. Catheter-directed thrombolysis is the infusion of thrombolytic agents directly into the occluded pulmonary arteries to increase local delivery and decrease the total dose. Suction thrombectomy involves the use of small- or large-bore catheters to mechanically aspirate a clot from the pulmonary arteries without the need for a thrombolytic agent. A thorough understanding of the various risk stratification schemes and the available evidence for each device is critical for optimal treatment of this complex entity. Multiple ongoing studies will improve our understanding of the role of catheter-based therapy for acute PE in the next 5-10 years. A multidisciplinary approach through PE response teams has become the management standard at most institutions. An invited commentary by Bulman and Weinstein is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

VA-ECMO-assisted aspiration thrombectomy in a patient presenting with acute massive PE with absolute contraindications to thrombolytics

Massive pulmonary embolism (PE) is a life-threatening complication of major surgery with a mortality rate up to 50%. First-line therapy for massive PE is systemic thrombolytics, but surgical patients are at high bleeding risk with absolute contraindications. As surgical thrombectomy carries a high burden of morbidity and mortality, endovascular interventions are becoming more common in these clinical scenarios. We report a case of a neurosurgical patient whose postoperative course was complicated by massive PE and subsequent cardiac arrest that required emergent venoarterial extracorporeal membrane oxygenation, followed by aspiration thrombectomy with the Inari FlowTriever Device (Inari Medical). The patient had immediate hemodynamic improvement with eventual recovery to baseline functional status.

VA-ECMO and thrombus aspiration in a pulmonary embolism patient with cardiac arrest and contraindications to thrombolytic therapy

Summary: A 57-year-old male patient with a history of proximal deep vein thrombosis on vitamin K antagonist therapy, suffered a recent hypertensive intracranial hemorrhage without significant neurological deficit. Three weeks later he presented with bilateral central pulmonary embolism. He had witnessed cardiac arrest and was put on veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Endovascular thrombectomy with an Aspirex device led to a significant improvement of hemodynamics. VA-ECMO was terminated after one day, an IVC filter was inserted, and he was discharged from ICU after 15 days. In conclusion, VA-ECMO and endovascular therapy are rescue strategies in patients with contraindications for thrombolysis.

Percutaneous mechanical thrombectomy and extracorporeal membranous oxygenation: A case series

BACKGROUND

Massive or high-risk pulmonary embolism (PE) is a potentially life-threatening diagnosis with significant morbidity and mortality if treatment is delayed. Extracorporeal membrane oxygenation (ECMO) and large bore thrombectomy (LBT) in isolation have been used to stabilize and treat patients with massive PE, however, literature describing the combination of both modalities is lacking. We present a case series involving 9 patients who underwent combined ECMO and LBT and their outcomes.

METHODS

This was a retrospective chart review of patients with confirmed PE, who underwent LBT and ECMO. We retrospectively captured clinical, therapeutic, and outcome data at the time of pulmonary embolism response team (PERT) activation and during the follow-up period for up to 90 days.

RESULTS

Nine patients who had PERT activation with confirmed PE diagnosis have undergone combined LBT and ECMO initiation since the advent of our PERT program. The median age was 57 (range 28-68) years. Six patients out of 9 (55%) had cardiac arrest before therapy. All patients exhibited right heart strain on computed tomography and echocardiogram. The median ECMO duration was 5 days (range 2.3-11.6 days), with mean hospitalization of 16.1 days (range 1.5-30.9). Mortality was 22% at 90-day follow-up period.

CONCLUSION

Patients with massive pulmonary embolism who suffer cardiac arrest have significant morbidity and mortality. ECMO in combination with LBT is a viable treatment option for patients with significant hemodynamic compromise.

Initial experience and early outcomes of the management of acute pulmonary embolism using the FlowTriever mechanical thrombectomy device

BACKGROUND

Submassive and massive pulmonary embolism is associated with a high risk of complications. We aimed to evaluate our initial experience with a mechanical thrombectomy device in the management of these patients.

METHODS

A single-center, retrospective study was performed in patients with acute submassive and massive pulmonary embolism treated with the FlowTriever device (Inari Medical, Irvine, CA, USA) between June 2019 and November 2020. Clinical and technical parameters were analyzed during the hospitalization and at 30- and 180-days after the procedure.

RESULTS

Fourteen patients were evaluated with a median (IQR) age of 60 (50-69) years and 64% were male. All had right heart strain as the main indication for thrombectomy. The procedure duration and fluoroscopic time was 52 (37-89) and 13 (9-24) minutes, respectively. There was 100% technical success, and the pulmonary arterial pressure went from 60 (48-65) mmHg to 40 (34-47) mmHg. Thrombolysis was used in two patients and nine patients required intensive care. 100% experienced improvement in symptoms at the time of discharge. There were no device-related complications, major bleeding events, myocardial infarctions, or deaths. Preprocedural hemoglobin was 13 (12-15) g/dL, and predischarge was 12 (10-13) g/dL. Overall postprocedural length of stay was three (2-6) days. All the patients were discharged with oral anticoagulation. There were no device-related complications or recurrence of embolism at 30 and 180 days.

CONCLUSIONS

The mechanical thrombectomy device for submassive and massive pulmonary embolism is promising and appears a safe and effective procedure with 100% technical success, no complications, short intensive care requirement/stay, and good early clinical outcomes.

Catheter-directed embolectomy for massive pulmonary embolism in a pediatric patient

Pulmonary embolisms can affect 0.9 in 100,000 children and carry high risk for mortality. However, management of pediatric pulmonary embolism is largely derived from adult studies and treatment often includes local or systemic thrombolytics or anticoagulation, which may pose unique bleeding risks in children and adolescents compared with adults. This report describes a case in which catheter-directed embolectomy was used to successfully manage a pediatric patient with high-risk/massive pulmonary embolism. This case suggests that catheter-directed embolectomy is an effective therapy in patients outside the adult population and more research is required to expand inclusion criteria for current catheter-directed embolectomy treatment paradigms. Moreover, this case emphasizes the need for dedicated pediatric pulmonary embolism response teams to best serve the pediatric population.

FlowTriever Retrieval System for the treatment of pulmonary embolism: overview of its safety and efficacy

INTRODUCTION

Pulmonary embolism (PE) is the third leading cause of cardiovascular mortality. There has been little change in PE mortality rates over the past two decades making this an appealing area for innovation and development.

AREAS COVERED

While anticoagulation (AC) and systemic thrombolysis (ST) are the mainstay treatments for high-risk PE and intermediate-high-risk PE with decompensation, advancements in catheter- based therapies offer potential alternatives. Areas covered here will include present guidelines for PE treatment and the landscape of catheter-directed therapies with a focus on the FlowTriever (FT) Retrieval System. Available safety and efficacy data will be reviewed. An online search via Google Scholar and PubMed with the keywords INARI Flowtriever, venous thromboembolism, and pulmonary embolism, alongside bibliographies of published articles, was undertaken as a review of the literature on the FlowTriever system for this device overview.

EXPERT OPINION

The five-year outlook on the role of catheter-directed therapies in the management of PE includes continued innovation in catheter-directed therapies and a number of high-quality trials on the horizon.

Bail-out treatment of pulmonary embolism using a large-bore aspiration mechanical thrombectomy device

We report on the first pulmonary embolism treatment via the large-bore aspiration mechanical thrombectomy device (Inari FlowTriever®) outside the USA, in a resuscitated patient on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) suffering from severe and acute right heart failure. In this particular high-risk patient population, where thrombolysis is mostly not applicable, this new technology could be a promising solution as the combination of large-bore thrombus aspiration and extraction successfully removes large emboli. In our case, right ventricular function improved rapidly after the procedure, ECMO could be weaned, and the patient was dismissed 2 weeks after. In summary, we provide a new therapeutic option for the often difficult treatment of pulmonary embolism in high-risk patients on VA-ECMO.

Hemodynamic compromise in pulmonary embolism: "A tale of two ventricles"

In acute pulmonary embolism (PE), low cardiac output (CO)-hypotension results from disparate ventricular conditions: The left ventricle (LV) is under-filled and contracting vigorously, whereas the right ventricle (RV) is failing and dilated. The proximate cause of LV preload deprivation is thrombus-induced pulmonary vascular obstruction; abruptly increased pulmonary vascular resistance (PVR) induces acute RV systolic dysfunction which further compromises trans-pulmonary flow. "Escalation of Care" interventions (thrombolytics and aspiration thrombectomy) improve systemic hemodynamics by increasing LV preload delivery directly by reducing PVR and indirectly by relief of the strained failing RV.