In-Hospital Mortality and Related Outcomes for Elevated Risk Acute Pulmonary Embolism Treated With Mechanical Thrombectomy Versus Routine Care

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.

Catheter-based therapy for high-risk or intermediate-risk pulmonary embolism: death and re-hospitalization

BACKGROUND AND AIMS

Catheter-based therapies (CBTs) have been developed as a treatment option in patients with pulmonary embolism (PE). There remains a paucity of data to inform decision-making in patients with intermediate-risk or high-risk PE. The aim of this study was to characterize in-hospital and readmission outcomes in patients with intermediate-risk or high-risk PE treated with vs. without CBT in a large retrospective registry.

METHODS

Patients hospitalized with intermediate-risk or high-risk PE were identified using the 2017-20 National Readmission Database. In-hospital outcomes included death and bleeding and 30- and 90-day readmission outcomes including all-cause, venous thromboembolism (VTE)-related and bleeding-related readmissions. Inverse probability of treatment weighting (IPTW) was utilized to compare outcomes between CBT and no CBT.

RESULTS

A total of 14 903 [2076 (13.9%) with CBT] and 42 829 [8824 (20.6%) with CBT] patients with high-risk and intermediate-risk PE were included, respectively. Prior to IPTW, patients with CBT were younger and less likely to have cancer and cardiac arrest, receive systemic thrombolysis, or be on mechanical ventilation. In the IPTW logistic regression model, CBT was associated with lower odds of in-hospital death in high-risk [odds ratio (OR) 0.83, 95% confidence interval (CI) 0.80-0.87] and intermediate-risk PE (OR 0.76, 95% CI 0.70-0.83). Patients with high-risk PE treated with CBT were associated with lower risk of 90-day all-cause [hazard ratio (HR) 0.77, 95% CI 0.71-0.83] and VTE (HR 0.46, 95% CI 0.34-0.63) readmission. Patients with intermediate-risk PE treated with CBT were associated with lower risk of 90-day all-cause (HR 0.75, 95% CI 0.72-0.79) and VTE (HR 0.66, 95% CI 0.57-0.76) readmission.

CONCLUSIONS

Among patients with high-risk or intermediate-risk PE, CBT was associated with lower in-hospital death and 90-day readmission. Prospective, randomized trials are needed to confirm these findings.

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.

Hemodialysis catheter-related right atrial thrombus treated with the FlowTriever system

Tunneled catheters are frequently used in patients with end-stage renal disease who require hemodialysis access. Catheter-related atrial thrombus is a documented complication of prolonged catheter use. The incidence of catheter-related atrial thrombus is 2% to 29%, with a high mortality rate approaching 20%, raising concerns for serious complications and death in the absence of an established universal management plan. This case series demonstrates the successful use of a minimally invasive approach to treat patients with intracardiac thrombus and high perioperative risk factors using mechanical and aspiration thrombectomy with the FlowTriever system (Inari Medical).

Mechanical thrombectomy is associated with shorter length of hospital stay and lower readmission rates compared with conservative therapy for acute submassive pulmonary embolism: a propensity-matched analysis

PURPOSE

To determine if mechanical thrombectomy (MT) for submassive pulmonary embolism (PE) positively impacts length of hospital stay (LOS), intensive care unit stay (ICU LOS), readmission rate, and in-hospital mortality compared with conservative therapy.

METHODS

This was a retrospective review of all patients with submassive PE who either underwent MT or conservative therapy (systemic anticoagulation and/or inferior vena cava filter) between November 2019 and October 2021. Pediatric patients (age <18) and those with low-risk and massive PEs were excluded from the study. Patient characteristics, comorbidities, vitals, laboratory values (cardiac biomarkers, hospital course, readmission rates, and in-hospital mortality) were recorded. A 2:1 propensity score match was performed on the conservative and MT cohorts based on age and the PE severity index (PESI) classification. Fischer's exact test, Pearson's χ2 test, and Student's t-tests were used to compare patient demographics, comorbidities, LOS, ICU LOS, readmission rates, and mortality rates, with statistical significance defined as P < 0.05. Additionally, a subgroup analysis based on PESI scores was assessed.

RESULTS

After matching, 123 patients were analyzed in the study, 41 in the MT cohort and 82 in the conservative therapy cohort. There was no significant difference in patient demographics, comorbidities, or PESI classification between the cohorts, except for increased incidence of obesity in the MT cohort (P = 0.013). Patients in the MT cohort had a significantly shorter LOS compared with the conservative therapy cohort (5.37 ± 3.93 vs. 7.76 ± 9.53 days, P = 0.028). However, ICU LOS was not significantly different between the cohorts (2.34 ± 2.25 vs. 3.33 ± 4.49, P = 0.059). There was no significant difference for in-hospital mortality (7.31% vs. 12.2%, P = 0.411). Of those that were discharged from the hospital, there was significantly lower incidence of 30-day readmission in the MT cohort (5.26% vs. 26.4%, P < 0.001). A subgroup analysis did not demonstrate that the PESI score had a significant impact on LOS, ICU LOS, readmission, or in-hospital mortality rates.

CONCLUSION

MT for submassive PE can reduce the total LOS and 30-day readmission rates compared with conservative therapy. However, in-hospital mortality and ICU LOS were not significantly different between the two groups.

Mechanical thrombectomy in intermediate- and high-risk acute pulmonary embolism: hemodynamic outcomes at three months

BACKGROUND

Mechanical thrombectomy has been shown to reduce thrombus burden and pulmonary artery pressure (PAP) and to improve right ventricular (RV) function in patients with high-risk or intermediate-high-risk pulmonary embolism (PE). As hemodynamic data after mechanical thrombectomy for PE are scarce, we aimed to assess the hemodynamic effects of mechanical thrombectomy in acute PE with right heart overload.

METHODS

In this prospective, open-label study, patients with acute symptomatic, computed tomography-documented PE with signs of right heart overload underwent mechanical thrombectomy using the FlowTriever System. Right heart catheterization was performed immediately before and after thrombectomy and after three months. Transthoracic echocardiography was performed before thrombectomy, discharge, and at three months. This analysis was done after 20 patients completed three months of follow-up.

RESULTS

Twenty-nine patients (34% female) underwent mechanical thrombectomy, of which 20 completed three months follow-up with right heart catheterization. Most patients were at high (17%) or intermediate-high (76%) risk and had bilateral PE (79%). Before thrombectomy, systolic PAP (sPAP) was severely elevated (mean 51.3 ± 11.6 mmHg). Mean sPAP dropped by -15.0 mmHg (95% confidence interval [CI]: -18.9 to -11.0; p < 0.001) immediately after the procedure and continued to decrease from post-thrombectomy to three months (-6.4 mmHg, 95% CI: -10-0 to -2.9; p = 0.002). RV/left ventricular (LV) ratio immediately reduced within two days by -0.37 (95% CI: -0.47 to -0.27; p < 0.001). The proportion of patients with a tricuspid annular plane systolic excursion (TAPSE)/sPAP ratio < 0.31 mm/mmHg decreased from 28% at baseline to 0% before discharge and at three months (p = 0.007). There were no procedure-related major adverse events.

CONCLUSIONS

Mechanical thrombectomy for acute PE was safe and immediately reduced PAP and improved right heart function. The reduction in PAP was maintained at three months follow-up.

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.

Percutaneous Management of High-Risk Pulmonary Embolism

Acute pulmonary embolism (PE) leads to an abrupt increase in pulmonary vascular resistance and right ventricular afterload, and when significant enough, can result in hemodynamic instability. High-risk PE is a dire cardiovascular emergency and portends a poor prognosis. Traditional therapeutic options to rapidly reduce thrombus burden like systemic thrombolysis and surgical pulmonary endarterectomy have limitations, both with regards to appropriate candidates and efficacy, and have limited data demonstrating their benefit in high-risk PE. There are growing percutaneous treatment options for acute PE that include both localized thrombolysis and mechanical embolectomy. Data for such therapies with high-risk PE are currently limited. However, given the limitations, there is an opportunity to improve outcomes, with percutaneous treatments options offering new mechanisms for clot reduction with a possible improved safety profile compared with systemic thrombolysis. Additionally, mechanical circulatory support options allow for complementary treatment for patients with persistent instability, allowing for a bridge to more definitive treatment options. As more data develop, a shift toward a percutaneous approach with mechanical circulatory support may become a preferred option for the management of high-risk PE at tertiary care centers.

Percutaneous Large-Bore Pulmonary Thrombectomy with the FlowTriever Device: Initial Experience in Intermediate-High and High-Risk Patients

OBJECTIVES

This retrospective cohort study investigates outcomes of patients with intermediate-high and high-risk pulmonary embolism (PE) who were treated with transfemoral mechanical thrombectomy (MT) using the large-bore Inari FlowTriever aspiration catheter system.

MATERIAL AND METHODS

Twenty-seven patients (mean age 56.1 ± 15.3 years) treated with MT for PE between 04/2021 and 11/2021 were reviewed. Risk stratification was performed according to European Society of Cardiology (ESC) guidelines. Clinical and hemodynamic characteristics before and after the procedure were compared with the paired Student's t test, and duration of hospital stay was analyzed with the Kaplan-Meier estimator. Procedure-related adverse advents were assessed.

RESULTS

Of 27 patients treated, 18 were classified as high risk. Mean right-to-left ventricular ratio on baseline CT was 1.7 ± 0.6. After MT, a statistically significant reduction in mean pulmonary artery pressures from 35.9 ± 9.6 to 26.1 ± 9.0 mmHg (p = 0.002) and heart rates from 109.4 ± 22.5 to 82.8 ± 13.8 beats per minute (p < 0.001) was achieved. Two patients died of prolonged cardiogenic shock. Three patients died of post-interventional complications of which a paradoxical embolism can be considered related to MT. One patient needed short cardiopulmonary resuscitation during the procedure due to clot displacement. Patients with PE as primary driver of clinical instability had a median intensive care unit (ICU) stay of 2 days (0.5-3.5 days). Patients who developed PE as a complication of an underlying medical condition spent 11 days (9.5-12.5 days) in the ICU.

CONCLUSION

In this small study population of predominantly high-risk PE patients, large-bore MT without adjunctive thrombolysis was feasible with an acceptable procedure-related complication rate.