A Randomized Trial of the Optimum Duration of Acoustic Pulse Thrombolysis Procedure in Acute Intermediate-Risk Pulmonary Embolism: The OPTALYSE PE Trial

Advanced Management of Intermediate- and High-Risk Pulmonary Embolism: JACC Focus Seminar

Intermediate-risk (submassive) pulmonary embolism (PE) describes normotensive patients with evidence of right ventricular compromise, whereas high-risk (massive) PE comprises those who have experienced hemodynamic decompensation with hypotension, cardiogenic shock, or cardiac arrest. Together, these 2 syndromes represent the most clinically challenging manifestations of the PE spectrum. Prompt therapeutic anticoagulation remains the cornerstone of therapy for both intermediate- and high-risk PE. Patients with intermediate-risk PE who subsequently deteriorate despite anticoagulation and those with high-risk PE require additional advanced therapies, typically focused on pulmonary artery reperfusion. Strategies for reperfusion therapy include systemic fibrinolysis, surgical pulmonary embolectomy, and a growing number of options for catheter-based therapy. Multidisciplinary PE response teams can aid in selection of appropriate management strategies, especially where gaps in evidence exist and guideline recommendations are sparse.

Hemodynamic Effects of Ultrasound-Assisted, Catheter-Directed, Very Low-Dose, Short-Time Duration Thrombolysis in Acute Intermediate-High Risk Pulmonary Embolism (from the EKOS-PL Study)

Ultrasound-assisted, catheter-directed, low-dose thrombolysis (USAT) at an average alteplase dose of 20 mg infused over 12 to 24 hours reversed right ventricular disfunction and improved pulmonary hemodynamics in intermediate-high-risk pulmonary embolism patients. As bleeding risk increases with the thrombolytic dose, establishing a minimal effective USAT dosing regimen is of clinical importance. We aimed to investigate hemodynamic effects and safety of a very low-alteplase-dose USAT of 10 mg administered within 5 hours. We included 12 consecutive intermediate-high-risk pulmonary embolism patients with symptoms duration of <14 days and proximal thrombi location in pulmonary arteries. Pulmonary Embolism Response Team decision-based fixed, bilateral ultrasound-assisted alteplase infusions at the rate of 1mg/hour/catheter for 5 hours through EKOS system catheters were made. The primary efficacy measure was the change in invasive systolic and mean pulmonary arteries pressure, and in cardiac index from USAT start to termination. Safety measures were 180-day all-cause death or cardiopulmonary decompensation and bleeding complications. The systolic pulmonary arteries pressure and mean pulmonary arteries pressure decreased from 53 (45.5 to 59) to 37.5 (27.5 to 40.5) mm Hg (p = 0.02) and from 29.5 (27.5 to 32) to 21.5 (15.5 to 25) mm Hg (p = 0.02), respectively. The cardiac index increased from 1.6 (1.5 to 1.8) to 2.2 (1.9 to 2.4) l/min/m², (p = 0.02). No deaths, decompensations, or need for therapy intensification occurred. There was 1 episode of access-site bleeding, which subsided after conservative management. No intracranial hemorrhages appeared. In conclusion, reduced dose and duration USAT improved pulmonary hemodynamics and cardiac function leading to cardiopulmonary stabilization in intermediate-high risk pulmonary embolism patients at a low periprocedural risk.

Aggressive Therapy for Acute Pulmonary Embolism: Systemic Thrombolysis and Catheter-Directed Approaches

Venous thromboembolism (VTE) is the third most common cause of cardiovascular disease after myocardial infarction and stroke. Population-based studies estimate that up to 94,000 new cases of pulmonary embolism (PE) occur in the United States annually with an increasing incidence with age. Mortality from PE is the greatest in the first 24 hours, with a decreased survival extending out 3 months. Thus, acute PE is a potentially fatal illness if not recognized and treated in a timely manner. Contemporary management includes systemic anticoagulation, thrombolysis, catheter-based procedures, and surgical embolectomy. This article reviews current clinical evidence and societal guidelines for the use of systemic and catheter-directed thrombolysis for treatment of acute PE.

Risk Stratification in Acute Pulmonary Embolism: The Latest Algorithms

Pulmonary embolism (PE) is a common clinical entity, which most clinicians will encounter. Appropriate risk stratification of patients is key to identify those who may benefit from reperfusion therapy. The first step in risk assessment should be the identification of hemodynamic instability and, if present, urgent patient consideration for systemic thrombolytics. In the absence of shock, there is a plethora of imaging studies, biochemical markers, and clinical scores that can be used to further assess the patients' short-term mortality risk. Integrated prediction models incorporate more information toward an individualized and precise mortality prediction. Additionally, bleeding risk scores should be utilized prior to initiation of anticoagulation and/or reperfusion therapy administration. Here, we review the latest algorithms for a comprehensive risk stratification of the patient with acute PE.

Predictors of reduced cardiac index in patients with acute submassive pulmonary embolism

OBJECTIVES

Determine the baseline clinical, laboratory, and echocardiographic values that predict reduced cardiac index (CI) among subjects with acute submassive pulmonary embolism (PE).

BACKGROUND

Submassive PE represents a large portion of acute PE population and there is controversy regarding optimal treatment strategies for these patients. There is significant heterogeneity within the submassive PE population and further refinement of risk stratification may aid clinical decision-making.

METHODS

We identified subjects with normotensive acute PE who underwent echocardiogram and right heart catheterization (RHC) prior to catheter-directed thrombolysis (CDT). We sought to determine the predictors of reduced CI, defined as CI < 2.2 L min^-1 m^-2 .

RESULTS

Thirty-two subjects met the inclusion criteria and 41% had reduced CI. Baseline variables did not distinguish subjects with reduced versus normal CI. Brain natriuretic peptide (BNP) was significantly different between the reduced versus normal CI groups (BNP 440 vs. 160 pg/ml, p = .004, respectively). Univariate logistic regression identified BNP, right ventricular (RV):left ventricular (LV) diameter ratio, tricuspid annular plane systolic excursion (TAPSE), and right ventricular systolic pressure as predictors of reduced CI. In a multivariate logistic regression model, only TAPSE was an independent predictor of reduced CI. ROC curve analysis identified the following optimal cut points for prediction of reduced CI: BNP > 216 pg/ml, RV:LV ratio > 1.41, or TAPSE <1.6 cm.

CONCLUSIONS

Almost half of subjects with acute submassive PE have reduced CI, despite normal systemic blood pressure. Optimal cut points for BNP, RV:LV ratio, and TAPSE were identified to predict reduced CI among patients with acute PE. These findings may aid in clinical decision-making and risk stratification of patients with acute submassive PE.

Effects of a Consensus-Based Pulmonary Embolism Treatment Algorithm and Response Team on Treatment Modality Choices, Outcomes, and Complications

Pulmonary embolism (PE) treatment depends on disease severity and risk of complications. Physician and institutional expertise may influence the use of reperfusion therapy (RT) such as systemic thrombolysis (SL) and catheter-directed interventions (CDI). We aimed to investigate the effects of a consensus-based treatment algorithm (TA) and subsequent implementation of PE response team (PERT) on RT modality choices and patient outcomes. A cohort of PE patients admitted to a tertiary care hospital between 2012 and 2017 was retrospectively evaluated. Demographics, clinical variables, RT selections, and patient outcomes during 3 consecutive 2-year periods (baseline, with TA, and with TA+PERT) were compared. Descriptive statistics were used for data analysis. A total of 1105 PE patients were admitted, and 112 received RT. Use of RT increased from 4.7% at baseline to 8.2% and 16.1% during the TA and TA+PERT periods. The primary RT modality transitioned from CDI to SL, and reduced-dose SL became most common. Treatment selection patterns remained unchanged after PERT introduction. Hospital length of stay decreased from 4.78 to 2.96 and 2.81 days (P < .001). Most of the hemorrhagic complications were minor, and their rates were similar across all 3 periods and between SL and CDI. No major hemorrhages occurred in patients treated with reduced-dose SL. In conclusion, TA and PERT represent components of a decision support system facilitating treatment modality selection, contributing to improved outcomes, and limiting complications. Treatment algorithm emerged as a factor providing consistency to PERT recommendations.

Current Endovascular Treatment Options in Acute Pulmonary Embolism

Acute pulmonary embolism (PE) is a significant cause of mortality and morbidity across the globe. Over the last few decades, there have been major therapeutic advances in acute PE management, including catheter-based therapy. However, the effectiveness of catheter-based therapy in acute PE is not supported by Level I evidence, making the use of this promising treatment rather controversial and ambiguous. In this paper, we discuss the risk stratification of acute PE and review the medical and endovascular treatment options. We also summarize and review the data supporting the use of endovascular treatment options in acute PE and describe the potential role of the PE response team.

Ultrasound-Facilitated Catheter-Directed Thrombolysis via Dual Right Upper Extremity Venous Access Into the Basilic Vein in a Case of Submassive Pulmonary Embolism

Traditionally, massive, life-threatening pulmonary embolism (PE) has been treated with systemic thrombolytic therapy while submassive and smaller acute PEs have been treated with systemic anticoagulation therapy. Given that thrombolytic therapy is associated with the risk of life-threatening complications including intracranial hemorrhage, it has not been routinely used or recommended for submassive PEs. In 2017, the Food and Drug administration (FDA) approved ultrasound-facilitated catheter-directed thrombolysis (USCDT) for acute massive and sub-massive pulmonary embolism. USCDT has primarily been performed using jugular or femoral venous access. There have been isolated reports of USCDT performed through upper extremity venous access. We present a case of USCDT in a submassive PE patient with dual right upper extremity venous access where both sheaths were advanced into the basilic vein (due to anatomic variation). Based on recent clinical trial data suggesting that shorted duration USCDT is as effective as longer duration, tissue plasminogen activator (tPA) was infused in this case for 6 hours. This strategy for intervention can enhance patient comfort with USCDT therapy and can be particularly helpful in patients at high risk for access site complications and those unable to lie supine for the long duration of infusion therapy.

Pulmonary thrombosis in Covid-19: before, during and after hospital admission

Disordered coagulation, endothelial dysfunction, dehydration and immobility contribute to a substantially elevated risk of deep venous thrombosis, pulmonary embolism (PE) and systemic thrombosis in coronavirus disease 2019 (Covid-19). We evaluated the prevalence of pulmonary thrombosis and reported RV (right ventricular) dilatation/dysfunction associated with Covid-19 in a tertiary referral Covid-19 centre. Of 370 patients, positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), 39 patients (mean age 62.3 ± 15 years, 56% male) underwent computed tomography pulmonary angiography (CTPA), due to increasing oxygen requirements or refractory hypoxia, not improving on oxygen, very elevated D-dimer or tachycardia disproportionate to clinical condition. Thrombosis in the pulmonary vasculature was found in 18 (46.2%) patients. However, pulmonary thrombosis did not predict survival (46.2% survivors vs 41.7% non-survivors, p = 0.796), but RV dilatation was less frequent among survivors (11.5% survivors vs 58.3% non-survivors, p = 0.002). Over the following month, we observed four Covid-19 patients, who were admitted with high and intermediate-high risk PE, and we treated them with UACTD (ultrasound-assisted catheter-directed thrombolysis), and four further patients, who were admitted with PE up to 4 weeks after recovery from Covid-19. Finally, we observed a case of RV dysfunction and pre-capillary pulmonary hypertension, associated with Covid-19 extensive lung disease. We demonstrated that pulmonary thrombosis is common in association with Covid-19. Also, the thrombotic risk in the pulmonary vasculature is present before and during hospital admission, and continues at least up to four weeks after discharge, and we present UACTD for high and intermediate-high risk PE management in Covid-19 patients.

Proposed Algorithm for Treatment of Pulmonary Embolism in COVID-19 Patients

There is mounting evidence that COVID-19 patients may possess a hypercoagulable profile that increases their risk for thromboembolic complications, including pulmonary embolism (PE). PE has been associated with an increase in morbidity, mortality, prolonged ventilation, and extended ICU admissions. Intervention is warranted in some patients who develop acute massive and submassive PEs. However, the development of PE in COVID-19 patients is often complicated by such factors as delay of diagnosis, confounding medical conditions, and strict isolation precautions. In addition, depleted cardiopulmonary reserve and prone positioning can make management of PE in these patients especially challenging for the physician. In this article, we review current understanding of PE in COVID-19 patients, summarize consensus data regarding the treatment of PE, and propose an algorithm to guide the management of COVID-19 patients with PE.

First-in-Human Study to Assess the Safety and Feasibility of the Bashir Endovascular Catheter for the Treatment of Acute Intermediate-Risk Pulmonary Embolism

BACKGROUND

The Bashir Endovascular Catheter (BEC) is a novel pharmaco-mechanical device designed to enhance thrombolysis by increasing the exposure of thrombus to endogenous and exogenous thrombolytics. The aim of this prospective, multicenter, single-arm study was to evaluate the feasibility and initial safety of the BEC in patients with acute intermediate-risk pulmonary embolism (PE).

METHODS

Patients with symptomatic PE and right ventricular to left ventricular diameter ratio ≥0.9 as documented by computer tomography angiography were eligible for enrollment. The primary safety end points were device related death or adverse events, and major bleeding within 72 hours after BEC directed therapy.

RESULTS

Nine patients were enrolled across 4 US sites. The total dose of r-tPA (recombinant tissue-type plasminogen activator) was 14 mgs in bilateral PE and 12 mgs in unilateral PE over 8 hours delivered via the expanded BEC. At 30-day follow-up, there were no deaths or device-related adverse events. At 48 hours post-BEC therapy, the right ventricular to left ventricular diameter ratio decreased from 1.52±0.26 to 0.97±0.06 (P=0.0009 [95% CI, 0.33-0.82]; 37.0% reduction). Thrombus burden as measured by the Modified Miller Index decreased from 25.4±5.3 to 16.0±4.0 (P=0.0005; [95% CI, 5.5-13.4]; 37.1% reduction).

CONCLUSIONS

In this early feasibility study of the BEC for intermediate-risk PE, there were no deaths or device-related adverse events and a significant reduction in right ventricular to left ventricular diameter ratio and thrombus burden. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03927508.

Thrombolytic therapy in acute venous thromboembolism

Although anticoagulation remains the mainstay of treatment of acute venous thromboembolism (VTE), the use of thrombolytic agents or thrombectomy is required to immediately restore blood flow to thrombosed vessels. Nevertheless, systemic thrombolysis has not clearly been shown to improve outcomes in patients with large clot burdens in the lung or legs as compared with anticoagulation alone; this is in part due to the occurrence of intracranial hemorrhage in a small percentage of patients to whom therapeutic doses of a thrombolytic drug are administered. Algorithms have been developed to identify patients at high risk for poor outcomes resulting from large clot burdens and at low risk for major bleeding in an effort to improve outcomes in those receiving thrombolytic therapy. In acute pulmonary embolism (PE), hemodynamic instability is the key determinant of short-term survival and should prompt consideration of immediate thrombolysis. In hemodynamically stable PE, systemic thrombolysis is not recommended and should be used as rescue therapy if clinical deterioration occurs. Evidence is accumulating regarding the efficacy of administering reduced doses of thrombolytic agents systemically or via catheters directly into thrombi in an effort to lower bleed rates. In acute deep venous thrombosis, catheter-directed thrombolysis with thrombectomy can be used in severe or limb-threatening thrombosis but has not been shown to prevent postthrombotic syndrome. Because the management of acute VTE can be complex, having a rapid-response team (ie, PE response team) composed of physicians from different specialties may aid in the management of severely affected patients.

Safety of the Inari FlowTriever device for mechanical thrombectomy in patients with acute submassive and massive pulmonary embolism and contraindication to thrombolysis

Objectives:

This report evaluates the safety of percutaneous mechanical thrombectomy with the Inari FlowTriever System (Inari Medical, Irvine, California) for the treatment of acute massive/submassive pulmonary embolism (PE) specifically in therapeutically anticoagulated patients with contraindication to thrombolysis.

Material and Methods:

A single-center retrospective chart review was performed on patients with contraindication to thrombolysis and massive/submassive PE who underwent FlowTriever thrombectomy between 2017 and 2019. Primary outcomes included procedure or device-related complications within 30 days of discharge. Secondary outcomes included technical and clinical success defined by improvement in mean pulmonary artery pressure (PAP), oxygen saturation, and heart rate.

Results:

Thirteen patients with contraindication to thrombolysis received FlowTriever thrombectomy with technical success achieved in all cases. Zero major or minor adverse events, technical complications, delayed procedure-related complications, or deaths within 30 days of hospital discharge occurred. Mean PAP decreased significantly by 19.1% (32.5 ± 13.3 mmHg to 26.3 ± 12.4 mmHg; P = 0.0074, 95% confidence interval (CI) 2.0–10.5 mmHg). Oxygen saturation improved post-procedure (increased 3.9 ± 3.8%; p = 0.0032, 95% CI 1.6– 6.1%) as did heart rate (decreased 22.2 ± 17.0 bpm; P < 0.001, 95% CI 11.9–32.4 bpm). Anticoagulation was maintained throughout every procedure and all patients were closed with purse-string suture only.

Conclusion:

FlowTriever mechanical thrombectomy appears safe for acute PE in therapeutically anticoagulated patients with contraindications to thrombolytic therapy. These patients may experience immediate hemodynamic improvements similar to those reported in other studies. Further data are needed to prospectively evaluate long-term safety in this population.

Use of hospital resources in the care of patients with intermediate risk pulmonary embolism

BACKGROUND

Risk stratification and management of hemodynamically stable pulmonary embolism remains challenging. Professional societies have published stratification schemes, but little is known about the management of patients with intermediate risk pulmonary embolism. We describe the care of these patients at an academic health system.

METHODS

Patient encounters from 1 January 2016 to 30 June 2017 were retrospectively identified utilizing a multihospital, electronic health record-based data warehouse. Using the 2019 European Society of Cardiology criteria, differences in hospital resource utilization, defined as intensive care unit admission, use of invasive therapies, and length of stay, were examined in patients with intermediate risk characteristics.

RESULTS

A cohort of 322 intermediate risk patients, including 165 intermediate-low and 157 intermediate-high risk patients, was identified. Intermediate-high risk patients more often underwent catheter-directed therapy (14.0% vs. 1.8%; P<0.001) compared to intermediate-low risk patients and had a 50% higher rate of intensive care unit admission (relative risk 1.50; 95% confidence interval 1.06, 2.12; P=0.023). There was no difference in median intensive care unit length of stay (2.7 vs. 2.0 days; P=0.761) or hospital length of stay (5.0 vs. 5.0 days; P=0.775) between intermediate-high risk and intermediate-low risk patients. Patients that underwent invasive therapies had a 3.8-day shorter hospital length of stay (beta -3.75; 95% confidence interval -6.17, -1.32; P=0.002).

CONCLUSION

This study presents insights into the hospital resource utilization of patients with intermediate risk pulmonary embolism. The 2019 European Society of Cardiology risk stratification criteria are a clinically relevant scheme that identifies patients more often treated with intensive care unit admission and advanced therapies.

In-hospital outcomes of catheter-directed thrombolysis in patients with pulmonary embolism

AIMS

Catheter-directed treatment of acute pulmonary embolism (PE) is technically advancing. Recent guidelines acknowledge this treatment option for patients with overt or imminent haemodynamic decompensation, particularly when systemic thrombolysis is contraindicated. We investigated patients with PE who underwent catheter-directed thrombolysis (CDT) in the German nationwide inpatient cohort.

METHODS AND RESULTS

Data from hospitalizations with PE (International Classification of Disease code I26) between 2005 and 2016 were collected by the Federal Office of Statistics in Germany. Patients with PE who underwent CDT (OPS 8-838.60 or OPS code 8-83b.j) were compared with patients receiving systemic thrombolysis (OPS code 8-020.8), and those without thrombolytic or other reperfusion treatment. The analysis was not prespecified; therefore, our findings can only be considered to be hypothesis generating. We analysed data from 978 094 hospitalized patients with PE. Of these, 41 903 (4.3%) patients received thrombolytic treatment [systemic thrombolysis in 4.2%, CDT in 0.1% (1175 patients)]. Among patients with shock, CDT was associated with lower in-hospital mortality compared to systemic thrombolysis [odds ratios (OR) 0.30 (95% 0.14-0.67); P = 0.003]. Intracranial bleeding occurred in 14 (1.2%) patients who received CDT. Among haemodynamically stable patients with right ventricular dysfunction (intermediate-risk PE), CDT also was associated with a lower risk of in-hospital mortality compared to systemic thrombolysis {OR 0.55 [95% confidence interval (CI) 0.40-0.75]; P < 0.001} or no thrombolytic treatment [0.45 (95% CI 0.33-0.62); P < 0.001].

CONCLUSION

In the German nationwide inpatient cohort, based on administrative data, CDT was associated with lower in-hospital mortality rates compared to systemic thrombolysis, but the overall rate of intracranial bleeding in patients who received CDT was not negligible. Prospective controlled data are urgently needed to determine the true value of this treatment option in acute PE.

Bleeding, death, and costs of care during hospitalization for acute pulmonary embolism: Insights from the Saint Luke's Outcomes of Pulmonary Embolism (SLOPE) study

Limited data exist that comprehensively describe the practical management, in-hospital outcomes, healthcare resource utilization, and rates of post-hospital readmission among patients with submassive and massive pulmonary embolism (PE). Consecutive discharges for acute PE were identified from a single health system over 3 years. Records were audited to confirm presence of acute PE, patient characteristics, disease severity, medical treatment, and PE-related invasive therapies. Rates of in-hospital major bleeding and death, hospital length of stay (LOS), direct costs, and hospital readmission are reported. From January 2016 to December 2018, 371 patients were hospitalized for acute massive or submassive PE. In-hospital major bleeding (12.1%) was common, despite low utilization of systemic thrombolysis (1.8%) or catheter-directed thrombolysis (3.0%). In-hospital death was 10-fold higher among massive PE compared to submassive PE (36.6% vs 3.3%, p < 0.001). Massive PE was more common during hospitalizations not primarily related to venous thromboembolism, including hospitalizations primarily for sepsis or infection (26.8% vs 8.2%, p = 0.001). Overall, the median LOS was 6.0 days (IQR, 3.0-11.0) and the median standardized direct cost of admissions was $10,032 (IQR, $4467-$20,330). Rates of all-cause readmission were relatively high throughout late follow-up but did not differ between PE subgroups. Despite low utilization of thrombolysis, in-hospital bleeding remains a common adverse event during hospitalizations for acute PE. Although massive PE is associated with high risk for in-hospital bleeding and death, those successfully discharged after a massive PE demonstrate similar rates of readmission compared to submassive PE into late follow-up.

The net benefit of thrombolysis in the management of intermediate risk pulmonary embolism: Systematic review and meta-analysis

Background

Benefit of thrombolytic therapy in patients with massive pulmonary embolism (PE) is evident. However, evidence supporting benefit in clinical outcomes of this approach in intermediate risk PE is lacking.

Objective

To determine the impact of thrombolysis on overall survival in intermediate risk PE patients.

Methods

We searched in MEDLINE (OVID), EMBASE, LILACS, and the Cochrane Central Register of Controlled Trials (CENTRAL) from present day. We also searched in other databases and unpublished literature. We included clinical trials without language restrictions. The risk of bias was evaluated with the Cochrane Collaboration's tool. The primary outcome was overall survival. Secondary outcomes were adverse events, including major bleeding, and all-cause mortality. The measure of the effect was the risk ratio with a 95% confidence interval (CI).

Results

We included 11 studies in the qualitative and quantitative analysis, with a total of 1855 patients. Risk of bias was variable among the study items. There were no results reported about overall survival in any of the studies. The risk ratio (RR) for all-cause mortality was 0.68 95% CI (0.40 to 1.16). The RR of overall bleeding, major bleeding and stroke were 2.72 95% CI (1.58 to 4.69), 2.17 95% CI (1.03 to 4.55), and 2.22 95% CI (0.17 to 28.73), respectively. Additionally, the RR for recurrent PE was 0.56 95% CI (0.23 to 1.37).

Conclusions

In patients with intermediate risk PE, the risk of bleeding is higher when thrombolysis is used. There was no significant difference between thrombolysis and anticoagulation in recurrence of PE, stroke, and all-cause mortality.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Thrombosis: Phlegmasia Cerulea Dolens Presenting with Venous Gangrene in a Child

A 12-year-old girl with severe acute respiratory syndrome coronavirus 2 infection presented as phlegmasia cerulea dolens with venous gangrene. Emergent mechanical thrombectomy was complicated by a massive pulmonary embolism and cardiac arrest, for which extracorporeal cardiopulmonary resuscitation and therapeutic hypothermia were used. Staged ultrasound-assisted catheter-directed thrombolysis was used for treatment of bilateral pulmonary emboli and the extensive lower extremity deep vein thrombosis while the patient received extracorporeal membrane oxygenation support. We highlight the need for heightened suspicion for occult severe acute respiratory syndrome coronavirus 2 infection among children presenting with unusual thrombotic complications.

Fibrinolytics for the treatment of pulmonary embolism

The use of fibrinolytic agents in acute pulmonary embolism (PE), first described over 50 years ago, hastens the resolution of RV stain, leading to earlier hemodynamic improvement. However, this benefit comes at the increased risk of bleeding. The strongest indication for fibrinolysis is in high-risk PE, or that characterized by sustained hypotension, while its use in patients with intermediate-risk PE remains controversial. Fibrinolysis is generally not recommended for routine use in intermediate-risk PE, although most guidelines advise that it may be considered in patients with signs of acute decompensation and an overall low bleeding risk. The efficacy of fibrinolysis often varies significantly between patients, which may be at least partially explained by several factors found to promote resistance to fibrinolysis. Ultimately, treatment decisions should carefully weigh the risks and benefits of the individual clinical scenario at hand, including the overall severity, the patient's bleeding risk, and the presence of factors known to promote resistance to fibrinolysis. This review aims to further explore the use of fibrinolytic agents in the treatment of PE including specific indications, outcomes, and special considerations.

FlowTriever System for mechanical thromboembolectomy

The systemic or catheter-directed infusion of thrombolytics benefits patients with massive and probably submassive pulmonary embolism. However, the risk of bleeding may offset benefits in a substantial number of patients. Percutaneous mechanical thromboembolectomy is an alternative to thrombolysis in those patients with contraindications to the lytic therapy, also potentially a way to avoid systemic or catheter-directed infusion of the thrombolytic all together. The Inari FlowTriever System (Inari Medical Inc, CA, USA) is the first US FDA-cleared large-bore aspiration thrombectomy device with pulmonary embolism thrombectomy indication. This article is a review of the FlowTriever System, its clinical use, current supportive literates and future research directions.

Management of Acute Pulmonary Embolism

Purpose of the Review

Over 100,000 cardiovascular-related deaths annually are caused by acute pulmonary embolism (PE). While anticoagulation has historically been the foundation for treatment of PE, this review highlights the recent rapid expansion in the interventional strategies for this condition.

Recent Findings

At the time of diagnosis, appropriate risk stratification helps to accurately identify patients who may be candidates for advanced therapeutic interventions. While systemic thrombolytics (ST) is the mostly commonly utilized intervention for high-risk PE, the risk profile of ST for intermediate-risk PE limits its use. Assessment of an individualized patient risk profile, often via a multidisciplinary pulmonary response team (PERT) model, there are various interventional strategies to consider for PE management. Novel therapeutic options include catheter-directed thrombolysis, catheter-based embolectomy, or mechanical circulatory support for certain high-risk PE patients. Current data has established safety and efficacy for catheter-based treatment of PE based on surrogate outcome measures. However, there is limited long-term data or prospective comparisons between treatment modalities and ST. While PE diagnosis has improved with modern cross-sectional imaging, there is interest in improved diagnostic models for PE that incorporate artificial intelligence and machine learning techniques.

Summary

In patients with acute pulmonary embolism, after appropriate risk stratification, some intermediate and high-risk patients should be considered for interventional-based treatment for PE.

Relationship of left ventricular outflow tract velocity time integral to treatment strategy in submassive and massive pulmonary embolism

Pulmonary embolism is associated with high rates of mortality and morbidity. It is important to understand direct comparisons of current interventions to differentiate favorable outcomes and complications. The objective of this study was to compare ultrasound-accelerated thrombolysis versus systemic thrombolysis versus anticoagulation alone and their effect on left ventricular outflow tract velocity time integral. This was a retrospective cohort study of subjects ≥18 years of age with a diagnosis of submassive or massive pulmonary embolism. The primary outcome was the percent change in left ventricular outflow tract velocity time integral between pre- and post-treatment echocardiograms. Ultrasound-accelerated thrombolysis compared to anticoagulation had a greater improvement in left ventricular outflow tract velocity time integral, measured by percent change. No significant change was noted between the ultrasound-accelerated thrombolysis and systemic thrombolysis nor systemic thrombolysis and anticoagulation groups. Pulmonary artery systolic pressure only showed a significant reduction in the ultrasound-accelerated thrombolysis versus anticoagulation group. The percent change of right ventricular to left ventricular ratios was improved when systemic thrombolysis was compared to both ultrasound-accelerated thrombolysis and anticoagulation. In this retrospective study of submassive or massive pulmonary embolisms, left ventricular outflow tract velocity time integral demonstrated greater improvement in patients treated with ultrasound-accelerated thrombolysis as compared to anticoagulation alone, a finding not seen with systemic thrombolysis. While this improvement in left ventricular outflow tract velocity time integral parallels the trend seen in mortality outcomes across the three groups, it only correlates with changes seen in pulmonary artery systolic pressure, not in other markers of echocardiographic right ventricular dysfunction (tricuspid annular plane systolic excursion and right ventricular to left ventricular ratios). Changes in left ventricular outflow tract velocity time integral, rather than echocardiographic markers of right ventricular dysfunction, may be considered a more useful prognostic marker of both dysfunction and improvement after reperfusion therapy.

Reperfusion therapies in pulmonary embolism-state of the art and expert opinion: A position paper from the "Unité de Soins Intensifs de Cardiologie" group of the French Society of Cardiology

Acute pulmonary embolism is a frequent cardiovascular emergency with an increasing incidence. The prognosis of patients with high-risk and intermediate-high-risk pulmonary embolism has not improved over the last decade. The current treatment strategies are mainly based on anticoagulation to prevent recurrence and reduce pulmonary vasculature obstruction. However, the slow rate of thrombus lysis under anticoagulation is unable to acutely decrease right ventricle overload and pulmonary vasculature resistance in patients with severe obstruction and right ventricle dysfunction. Therefore, patients with high-risk and intermediate-high-risk pulmonary embolism remain a therapeutic challenge. Reperfusion therapies may be discussed for these patients, and include systemic thrombolysis, catheter-directed therapies and surgical thrombectomy. High-risk patients require systemic thrombolysis, but may have contraindications as a result of the high risk of bleeding. In addition, intermediate-high-risk patients should not receive systemic thrombolysis, despite its high efficacy, because of prohibitive bleeding complications. Recently, percutaneous reperfusion techniques have been developed to acutely decrease pulmonary vascular obstruction with lower-dose or no thrombolytic agents and, thus, potentially higher safety than systemic thrombolysis. Some of these techniques improve key haemodynamic variables. Cardiac surgical techniques and venoarterial extracorporeal membrane oxygenation as temporary circulatory support may be useful in selected cases. The development of pulmonary embolism centres with multidisciplinary pulmonary embolism teams is mandatory to enable adequate use of reperfusion and improve outcomes. We aim to present the state of the art regarding reperfusion therapies in pulmonary embolism, but also to provide guidance on their indications and patient selection.

Massive pulmonary embolism in patients with extreme bleeding risk: a case series on the successful use of ultrasound-assisted, catheter directed thrombolysis in a district general hospital

Massive pulmonary embolism (PE), characterised by profound arterial hypotension, is a life-threatening emergency with a 90-day mortality of over 50%. Systemic thrombolysis can significantly reduce the risk of death or cardiovascular collapse in these patients, by around 50%, but these benefits are offset by a fivefold increased risk of intracranial haemorrhage and major bleeding, which may limit its use in patients at high risk of catastrophic haemorrhage. We describe a case series of 3 patients presenting with massive PE, each with extreme risk of bleeding and contra-indication to systemic thrombolysis, treated successfully with ultrasound-assisted, catheter directed thrombolysis (U-ACDT). Our experience of this novel technique using the EkoSonic Endovascular System (Ekos, BTG, London, UK) on carefully selected patients has demonstrated the potential to improve clinical status in shocked patients, with minimal bleed risk. There have been several clinical studies evaluating the Ekos system. Both the ULTIMA and SEATTLE II studies have shown significant reductions in RV/LV ratio by CT scanning when compared to standard anticoagulation in patients with intermediate-risk PE, with minimal bleeding complications. However, there is a pressing need for a randomised trial demonstrating improvement in robust clinical outcomes when comparing U-ACDT to simple anticoagulation. We believe that this case series adds new insight and highlights the potential of catheter directed thrombolysis in this high-risk patient cohort and consideration should be made to its use in cases where systemic thrombolysis is felt to be too high risk.

Regional and Conducted Vascular Effects of Endovascular Ultrasound Catheters

Intra-vascular ultrasound catheters are used clinically to facilitate clot lysis. We hypothesized that these devices could also directly lower microvascular resistance and increase tissue perfusion through established shear-dependent pathways. In mice, either the proximal hind-limb muscles or the upstream femoral artery alone was exposed to an endovascular ultrasound catheter (2.3 MHz, 0.5-1.1 MPa) for 10 min. Quantitative microvascular perfusion imaging in the hind limbs exposed to the endovascular ultrasound system exhibited a more-than-twofold increase in flow (p < 0.01) compared with the contralateral control limb after exposure of either the muscle or the femoral artery alone. Using an in vivo optical imaging reporting system, an eight- to ninefold increase in tissue adenosine triphosphate (ATP) was detected in the region of insonification (p = 0.006). Ultrasound was found to produce an immediate release of ATP from ex vivo erythrocytes (p = 0.03). In situ electrochemical sensing revealed an immediate increase in nitric oxide with initiation of ultrasound which returned to baseline within 5 min of termination, as well as ultrasound-triggered nitric oxide (NO) release from erythrocytes. These data indicate that non-cavitating ultrasound produced by endovascular catheters can reduce vascular resistance and increase flow through recognized shear-dependent vasodilator pathways involving purinergic signaling and NO.

Acute pulmonary embolism multimodality imaging prior to endovascular therapy

The manuscript discusses the application of CT pulmonary angiography, ventilation–perfusion scan, and magnetic resonance angiography to detect acute pulmonary embolism and to plan endovascular therapy. CT pulmonary angiography offers high accuracy, speed of acquisition, and widespread availability when applied to acute pulmonary embolism detection. This imaging modality also aids the planning of endovascular therapy by visualizing the number and distribution of emboli, determining ideal intra-procedural catheter position for treatment, and signs of right heart strain. Ventilation–perfusion scan and magnetic resonance angiography with and without contrast enhancement can also aid in the detection and pre-procedural planning of endovascular therapy in patients who are not candidates for CT pulmonary angiography.

One-Year Echocardiographic, Functional, and Quality of Life Outcomes After Ultrasound-Facilitated Catheter-Based Fibrinolysis for Pulmonary Embolism

Accelerated tPA (tissue-type plasminogen activator) dosing regimens for ultrasound-facilitated, catheter-directed fibrinolysis improve short-term computed tomographic-measured right ventricular (RV)-to-left ventricular diameter ratio in massive and submassive pulmonary embolism. The impact on RV remodeling, functional status, and quality of life over the long-term remains unclear.

The PERT Concept: A Step-by-Step Approach to Managing Pulmonary Embolism

Pulmonary embolism (PE) is a major source of morbidity and mortality. The presentation of acute PE varies, ranging from few or no symptoms to sudden death. Patient outcome depends on how well the right ventricle can sustain the increased afterload caused by the embolic burden. Careful risk stratification is critical, and the PE response team (PERT) concept offers a rapid and multidisciplinary approach. Anticoagulation is essential unless contraindicated; thrombolysis, surgical embolectomy, and catheter-directed approaches are also available. Clinical consensus statements have been published that offer a guide to PE management, but areas remain for which the evidence is inadequate. Although the management of low-risk and high-risk patients is more straightforward, optimal management of intermediate-risk patients remains controversial. In this document, we offer a case-based approach to PE management, beginning with diagnosis and risk stratification, followed by therapeutic alternatives, and finishing with follow-up care.

Expert opinion on the creating and operating of the regional Pulmonary Embolism Response Teams (PERT). Polish PERT Initiative

Pulmonary Embolism Response Team (PERT) is a multidisciplinary team established to stratify risk and choose optimal treatment in patients with acute pulmonary embolism (PE). Established for the first time at Massachusetts General Hospital in 2013, PERT is based on a concept combining a Rapid Response Team and a Heart Team. The growing role of PERTs in making individual therapeutic decisions is identified, especially in hemodynamically unstable patients with contraindications to thrombolysis or with co-morbidities, as well as in patients with intermediate-high risk in whom a therapeutic decision may be difficult. The purpose of this document is to define the standards of PERT under Polish conditions, based on the experience of teams already operating in Poland, which formed an agreement called the Polish PERT Initiative. The goals of Polish PERT Initiative are: improving the treatment of patients with PE at local, regional and national levels, gathering, assessing and sharing data on the effectiveness of PE treatment (including various types of catheter-directed therapy), education on optimal treatment of PE, creating expert documents and supporting scientific research, as well as cooperation with other communities and scientific societies.

Invasive Strategies for the Treatment of Pulmonary Embolism. Where Are We in 2020?

Pulmonary Embolism (PE) is the third most common cause of cardiovascular mortality in the United States, with 60,000-100,000 deaths per year following myocardial infarction and stroke. During the past 5 years, there has been an introduction of novel interventions as a result of a renewed interest in optimizing PE management, particularly among those individuals with more severe disease of hemodynamic significance. The cornerstone treatment for PE is anticoagulation. More aggressive alternatives have been considered for patients with intermediate and high-risk PE. In general, these options can be grouped into 3 different categories: systemic thrombolysis, catheter-directed interventions, and surgical embolectomy. Systemic thrombolysis has shown statistical benefit in several randomized trials for intermediate- and high-risk PE, however, this benefit has been offset by an elevated risk of major bleeding and intracerebral hemorrhage, limiting their use in clinical practice. Catheter-directed thrombolysis refers to catheter-directed injection of a thrombolytic drug directly into the pulmonary artery. Three interventional devices (EKOSonic endovascular system, FlowTriever embolectomy device and the Indigo thrombectomy system) have recently been cleared by the US Food and Drug Administration for marketing, and several others are in various stages of development. As of today, catheter-based interventions are limited to small randomized trials and single arm-prospective studies focused on short-term surrogate endpoints. Although single arm studies carry some value establishing the preliminary safety and effectiveness of these devices, they are not sufficient to stratify risk and guide clinical practice. Furthermore, no trials have been performed with enough power to assess potential mortality benefit with the use of catheter-directed thrombolysis or catheter-based embolectomy devices, hence treatment decisions continue to be influenced by individual risk of bleeding, the location of thrombus and operator expertise until additional evidence becomes available.

Acute treatment of venous thromboembolism

All patients with venous thromboembolism (VTE) should receive anticoagulant treatment in the absence of absolute contraindications. Initial anticoagulant treatment is crucial for reducing mortality, preventing early recurrences, and improving long-term outcome. Treatment and patient disposition should be tailored to the severity of clinical presentation, to comorbidities, and to the potential to receive appropriate care in the outpatient setting. Direct oral anticoagulants (DOACs) used in fixed doses without laboratory monitoring are the agents of choice for the treatment of acute VTE in the majority of patients. In comparison with conventional anticoagulation (parenteral anticoagulants followed by vitamin K antagonists), these agents showed improved safety (relative risk [RR] of major bleeding, 0.61; 95% confidence interval [CI], 0.45-0.83) with a similar risk of recurrence (RR, 0.90; 95% CI, 0.77-1.06). Vitamin K antagonists or low molecular weight heparins are still alternatives to DOACs for the treatment of VTE in specific patient categories such as those with severe renal failure or antiphospholipid syndrome, or cancer, respectively. In addition to therapeutic anticoagulation, probably less than 10% of patients require reperfusion by thrombolysis or interventional treatments; those patients are hemodynamically unstable with acute pulmonary embolism, and a minority of them have proximal limb-threatening deep vein thrombosis (DVT). The choice of treatment should be driven by the combination of evidence from clinical trials and by local expertise. The majority of patients with acute DVT and a proportion of selected hemodynamically stable patients with acute pulmonary embolism can be safely managed as outpatients.

Analysis of pulmonary embolism patients treated with EkoSonic™ endovascular system

Background

The aim of this study was to evaluate the efficacy and the safety of the EkoSonic™ endovascular system applications in patients hospitalized with the diagnosis of intermediate-high-risk pulmonary embolism.

Methods

Between January 2018 and March 2019, a total of 15 patients (7 males, 8 females; mean age 64.7±17.8 years, range, 35 to 90 years) who underwent ultrasound-accelerated thrombolysis using the EkoSonic™ endovascular system for pulmonary embolism were retrospectively analyzed. The diagnosis of pulmonary embolism was made based on pulmonary computed tomography angiography. All patients were evaluated by echocardiography for right ventricular dysfunction and serum levels of troponin I and brain natriuretic peptide were recorded.

Results

The mean arterial blood gas oxygen saturation values of the patients before and after the procedure were 86.3±3.5% and 94.2±2.5%, respectively, indicating a statistically significant difference (p=0.001). The mean partial oxygen pressure values before and after the procedure were 73.3±7.7 mmHg and 90.7±5.0 mmHg, respectively, indicating a statistically significant difference (p=0.001). There was also a statistically significant difference in the mean right ventricular diameter before and after the procedure (p=0.001). The mean pre- and post-procedural pulmonary arterial pressure was 44±7.1 mmHg and 36.3±4.5 mmHg, respectively, indicating a statistically significant difference (p=0.001). Of the patients, 93.7% were free from post-procedural complications.

Conclusion

The EkoSonic™ endovascular system improved right ventricular dysfunction, decreased pulmonary arterial pressure, and improved oxygenation in patients with intermediate-high-risk pulmonary embolism without increasing the risk for bleeding.

Pulmonary embolism in acute medicine: a case-based review incorporating latest guidelines in the COVID-19 era

Pulmonary embolism remains an important cause of morbidity and mortality in the UK, particularly following the outbreak of the novel coronavirus 2019 (COVID-19), where those infected have an increased prevalence of venous thromboembolic events. The pathophysiology in COVID-19 patients is thought to relate to a thromboinflammatory state within the pulmonary vasculature, triggered by the infection, but other risk factors such as reduced mobility, prolonged immobilisation and dehydration are likely to contribute. Several societies have released comprehensive guidelines emphasising the importance of risk stratification in patients with acute pulmonary embolism. They advocate the use of clinically validated risk scores in conjunction with biochemical and imaging results. Patients with mild disease can now be managed in the outpatient setting and with newly developed therapies, such as catheter-directed thrombolysis, becoming available in more centres, treatment options for those with more severe disease are also expanding. This article presents four theoretical but realistic cases, each diagnosed with acute pulmonary embolism, but differing in levels of severity. These demonstrate how the guidelines can be applied in a clinical setting, with particular focus on risk stratification and management.

Interventional Radiology Therapy: Inferior Vena Cava Filter and Catheter-based Therapies

Endovascular management of pulmonary embolism can be divided into therapeutic and prophylactic treatments. Prophylactic treatment includes inferior vena cava filter placement, whereas endovascular therapeutic interventions include an array of catheter-directed therapies. The indications for both modalities have evolved over the last decade as new evidence has become available.

Predictors of Treatment Response Following Ultrasound-Facilitated Catheter-Directed Thrombolysis for Submassive and Massive Pulmonary Embolism

Background:

Little is known about which factors predict improvement in clinical and imaging parameters among patients undergoing catheter-directed thrombolysis for submassive or massive pulmonary embolism. The identification of such predictors may allow for more appropriate patient selection for ultrasound-facilitated catheter-directed thrombolysis.

Methods:

We conducted a retrospective cohort analysis of patients from the SEATTLE II trial (Prospective, Single-Arm, Multi-Center Trial of EkoSonic Endovascular System and Activase for Treatment of Acute Pulmonary Embolism) to identify clinical characteristics that independently predict pulmonary artery pressures, right ventricular-to-left ventricular (RV/LV) diameter ratio, and modified Miller angiographic index following ultrasound-assisted catheter-directed thrombolysis. Eligible patients had submassive or massive pulmonary embolism and an RV/LV diameter ratio ≥0.9 on chest computed tomography. Multivariable linear regression was used to identify independent clinical predictors of each outcome.

Results:

One hundred fifty patients with massive (n=31) or submassive (n=119) pulmonary embolism were enrolled. Mean (±SD) baseline and postprocedure RV/LV diameter ratio, pulmonary artery systolic pressure, and modified Miller Score were 1.59 (±0.39) and 1.14 (±0.2), 51.45 (±16.0), and 37.47 (±11.9), and 23.0 (±5.7) and 15.7 (±5.9), respectively. The multivariable model adjusted R 2 for absolute change in RV/LV ratio, pulmonary artery systolic pressure, modified Miller Score was 0.71, 0.57, and 0.43, respectively. After adjusting for age, gender, and baseline RV/LV ratio, pulmonary artery systolic pressure, and modified Miller Score, patients with higher body mass index, renal or hepatic dysfunction, active smoking, or a higher baseline heart rate showed less improvement.

Conclusions:

Patients with more life-threatening pulmonary embolism may derive the greatest benefit from ultrasound-assisted, catheter-directed thrombolysis.

Outcomes of catheter-directed versus systemic thrombolysis for the treatment of pulmonary embolism: A real-world analysis of national administrative claims

Catheter-directed thrombolysis (CDT) and systemic thrombolysis (ST) are used to treat intermediate/high-risk pulmonary embolism (PE) in the absence of comparative safety and effectiveness data. We utilized a large administrative database to perform a comparative safety and effectiveness analysis of catheter-directed versus systemic thrombolysis. From the Optum^® Clinformatics^® Data Mart private-payer insurance claims database, we identified 100,744 patients hospitalized with PE between 2004 and 2014. We extracted demographic characteristics, high-risk PE features, components of the Elixhauser Comorbidity Index, and outcomes including intracranial hemorrhage (ICH), all-cause bleeding, and mortality among all patients receiving CDT and ST. We used propensity score methods to compare outcomes between matched cohorts adjusted for observed confounders. A total of 1915 patients (1.9%) received either CDT (n = 632) or ST (n = 1283). Patients in the CDT group had fewer high-risk features including less shock (5.4 vs 11.1%; p < 0.001) and cardiac arrest (6.8 vs 11.0%; p = 0.004). In 1:1 propensity-matched groups, ICH rates were 1.9% in both the CDT and ST groups (p = 1.0). All-cause bleeding was higher in the CDT group (15.9 vs 8.7%; p < 0.001), while in-hospital mortality was lower (6.5 vs 10.0%; p = 0.02). Among a nationally representative cohort of patients with PE at higher risk for mortality, CDT was associated with similar ICH rates, increased all-cause bleeding, and lower short and intermediate-term mortality when compared with ST. The competing risks and benefits of CDT in real-world practice suggest the need for large-scale randomized clinical trials with appropriate comparator arms.

Concise Review of the Clinical Approach to the Exclusion and Diagnosis of Pulmonary Embolism in 2020

Pulmonary embolism has extremely varied clinical presentations and can be difficult to diagnose. Clinical decision rules can help determine the probability of pulmonary embolism by assessment of the clinical presentation. After the diagnosis, several prognostic rules can be used to risk-stratify and facilitate outpatient treatment of pulmonary embolism. This review addresses the utility of clinical decision rules, biomarkers in the diagnosis of pulmonary emoblism, high-risk patient phenotypes, the use of this data to make disposition decisions for patients with a diagnosis of PE, and recent shifts in the management of pulmonary embolism in the clinical setting.

Evolution of Acute Pulmonary Embolism Management: Review Article

Acute pulmonary emboli are a major cause of morbidity and mortality and require prompt evaluation, diagnosis, and treatment. To date, anticoagulation using low molecular weight heparin or non-Vitamin K oral anticoagulants has been the mainstay of treatment in the subset of patients in whom pulmonary embolism does not compromise hemodynamics. On the other hand however, patients with massive pulmonary embolism and shock, thrombolytic therapy is necessary. This raises the question whether ultrasound-assisted catheter directed thrombolytic delivery might be superior to systemic administration. This review article aims to consolidate recent literature to help achieve a better understanding toward the utility of catheter directed therapy.

Interventional Therapies in Acute Pulmonary Embolism

Treatment of acute pulmonary embolism (PE) historically included anticoagulation and systemic thrombolytic therapy. More recently, catheter guided interventions provided promise of mitigating bleeding risks usually associated with systemic thrombolysis in intermediate to high risk PE patients. Catheter based interventions can broadly be divided into catheter directed thrombolysis and catheter based embolectomy. Both modalities are currently undergoing active research and each has their respective risks and benefits. The decision to administer these advanced therapies for acute PE can be challenging but can be accomplished via a multi-disciplinary PE response team.