The Efficacy of Rotational Thrombectomy on the Mortality of Patients with Massive and Submassive Pulmonary Embolism

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.

Novel Challenges and Therapeutic Options for Pulmonary Embolism and Deep Vein Thrombosis

Acute pulmonary embolism (PE), often resulting from deep vein thrombosis (DVT), is the third most frequent cause of cardiovascular death and is associated with increasing incidence, causing considerable morbidity and mortality. This review aims to evaluate the efficacy, safety, and outcomes of treatment options in the management of acute PE and DVT, encompassing both established and emerging technologies, such as catheter-directed thrombolysis, aspiration thrombectomy, and other endovascular techniques. A comprehensive literature review was conducted, assessing clinical studies, trials, and case reports that detail the use of percutaneous interventions for PE and DVT and analyzing the advantages and disadvantages of each percutaneous system. Several percutaneous treatments have shown promising results, especially in cases where rapid thrombus resolution is critical, such as in high- and intermediate-high-risk patients. The incidence of major complications, such as bleeding, remains a consideration, though it is generally manageable with proper patient selection and technique. It is fundamentally important to tailor the specific treatment strategy to the clinical and anatomical characteristics of each patient. Percutaneous treatments for acute PE and DVT represent valuable options in the therapeutic arsenal, offering enhanced outcomes in appropriately selected patients. Ongoing advancements in technology and technique, along with comprehensive clinical trials, are essential to further define the role and optimize the use of these interventions.

Percutaneous interventions for pulmonary embolism

Pulmonary embolism (PE) ranks as a leading cause of in-hospital mortality and the third most common cause of cardiovascular death. The spectrum of PE manifestations varies widely, making it difficult to determine the best treatment approach for specific patients. Conventional treatment options include anticoagulation, thrombolysis, or surgery, but emerging percutaneous interventional procedures are being investigated for their potential benefits in heterogeneous PE populations. These novel interventional techniques encompass catheter-directed thrombolysis, mechanical thrombectomy, and hybrid approaches combining different mechanisms. Furthermore, inferior vena cava filters are also available as an option for PE prevention. Such interventions may offer faster improvements in right ventricular function, as well as in pulmonary and systemic haemodynamics, in individual patients. Moreover, percutaneous treatment may be a valid alternative to traditional therapies in high bleeding risk patients and could potentially reduce the burden of mortality related to major bleeds, such as that of haemorrhagic strokes. Nevertheless, the safety and efficacy of these techniques compared to conservative therapies have not been conclusively established. This review offers a comprehensive evaluation of the current evidence for percutaneous interventions in PE and provides guidance for selecting appropriate patients and treatments. It serves as a valuable resource for future researchers and clinicians seeking to advance this field. Additionally, we explore future perspectives, proposing "percutaneous primary pulmonary intervention" as a potential paradigm shift in the field.

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.

Cutting-Edge Techniques and Drugs for the Treatment of Pulmonary Embolism: Current Knowledge and Future Perspectives

Pulmonary embolism (PE) is a potentially life-threatening condition requiring prompt diagnosis and treatment. Recent advances have led to the development of newer techniques and drugs aimed at improving PE management, reducing its associated morbidity and mortality and the complications related to anticoagulation. This review provides an overview of the current knowledge and future perspectives on PE treatment. Anticoagulation represents the first-line treatment of hemodynamically stable PE, direct oral anticoagulants being a safe and effective alternative to traditional anticoagulation: these drugs have a rapid onset of action, predictable pharmacokinetics, and low bleeding risk. Systemic fibrinolysis is suggested in patients with cardiac arrest, refractory hypotension, or shock due to PE. With this narrative review, we aim to assess the state of the art of newer techniques and drugs that could radically improve PE management in the near future: (i) mechanical thrombectomy and pulmonary embolectomy are promising techniques reserved to patients with massive PE and contraindications or failure to systemic thrombolysis; (ii) catheter-directed thrombolysis is a minimally invasive approach that can be suggested for the treatment of massive or submassive PE, but the lack of large, randomized controlled trials represents a limitation to widespread use; (iii) novel pharmacological approaches, by agents inhibiting thrombin-activatable fibrinolysis inhibitor, factor Xia, and the complement cascade, are currently under investigation to improve PE-related outcomes in specific settings.

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.

Percutaneous thrombectomy in patients with intermediate- and high-risk pulmonary embolism and contraindications to thrombolytics: a systematic review and meta-analysis

Catheter-directed interventions have slowly been gaining ground in the treatment of pulmonary embolism (PE), especially in patients with increased risk of bleeding. The goal of this study is to summarize the evidence for the efficacy and safety of percutaneous thrombectomy (PT) in patients with contraindications to systemic and local thrombolysis. We performed a systematic review and meta-analysis using MEDLINE, Cochrane, Scopus and the Web of Science databases for studies from inception to March 2022. We included patients with intermediate- and high-risk PE with contraindications to thrombolysis; patients who received systematic or local thrombolysis were excluded. Primary endpoint was in-hospital and 30-day mortality, with secondary outcomes based on hemodynamic and radiographic changes. Major bleeding events were assessed as a safety endpoint. Seventeen studies enrolled 455 patients, with a mean age of 58.6 years and encompassing 50.4% females. In-hospital and 30-day mortality rates were 4% (95% CI 3-6%) and 5% (95% CI 3-9%) for all-comers, respectively. We found a post-procedural reduction in systolic and mean pulmonary arterial pressures by 15.4 mmHg (95% CI 7-23.7) and 10.3 mmHg (95% CI 3.1-17.5) respectively. The RV/LV ratio and Miller Index were reduced by 0.42 (95% CI 0.38-46) and 7.8 (95% CI 5.2-10.5). Major bleeding events occurred in 4% (95% CI 3-6%). This is the first meta-analysis to report pooled outcomes on PT in intermediate- and high-risk PE patients without the use of systemic or local thrombolytics. The overall mortality rate is comparable to other contemporary treatments, and is an important modality particularly in those with contraindications for adjunctive thrombolytic therapy. Further studies are needed to understand the interplay of anticoagulation with PT and catheter-directed thrombolysis.

Submassive Pulmonary Embolism in the Setting of Intracerebral Hemorrhage: A Case of Suction Thrombectomy

Pulmonary embolism (PE) in the setting of intracerebral hemorrhage (ICH) is an unfortunate, challenging, and highly morbid clinical problem. Interventional strategies have lower associated bleeding risks than the standby for PE treatment: systemic anticoagulation. Despite this benefit, there are few examples in the literature of its utilization in the management of PE in the setting of ICH. This present case provides an example of the successful utilization of suction thrombectomy to manage PE in the setting of ICH. An 80-year-old female presented to an outside hospital with complaints of dizziness, headache, nausea, and vomiting of abrupt onset one hour before arrival. Computed tomography (CT) of the head with CT Angiography (CTA) of the head and neck was performed and demonstrated hemorrhage in all ventricles; most prominently within the left lateral ventricle. Magnetic Resonance Imaging (MRI) of the brain suggested that the cause of her hemorrhage was reperfusion injury after a small acute infarction in the left internal capsule in the setting of anticoagulant use. Ten days after her diagnosis of ICH, a submassive PE was diagnosed with a class IV pulmonary embolism severity index (PESI). An interdisciplinary evaluation was conducted between hospitalist medicine, neurology, neurosurgery, and interventional radiology. A successful suction thrombectomy was performed on hospital day 11. No new neurologic deficits were appreciated post-procedure. The patient's heart rate remained elevated but improved. Blood pressure remained controlled. The patient was weaned off oxygen to room air. Neurosurgery assessed the patient to be of acceptable risk for discharge with the further deferment of anticoagulation until repeat CT head six weeks after discharge. The patient was discharged on hospital day 14. Treating PE in the setting of ICH is without clear guidelines. The appropriate treatment modality is reliant upon the clinical judgment and the individual details of each case. In this case, a high PESI with imaging demonstrating a stable hematoma without evidence of new blood resulted in the decision to use a suction thrombectomy. More research is needed to develop consistent evidence-based guidelines for this clinical challenge.

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.

Catheter-directed interventions for pulmonary embolism

Pulmonary embolism (PE) is common, life-threatening, and often recurrent among survivors. The clinical manifestations of PE range from incidental detection to sudden death, with approximately one-third of PE deaths occurring suddenly. State-of-the-art management of acute PE relies on early detection, risk stratification based on clinical, imaging, and biomarker criteria, and multidisciplinary decision-making. The primary goal of catheter-directed interventions for acute PE is to interrupt the cycle of right ventricular failure, hypoperfusion, and oxygen supply/demand imbalance by increasing the cross-sectional area of the patent pulmonary vasculature, thereby lowering resistance and alleviating V/Q mismatch. Innovations in percutaneous interventions have led to several approaches described in this review: rheolytic thrombectomy, catheter-directed thrombolysis, and aspiration or mechanical thrombectomy. The central challenge moving forward will be integrating growing clinical trial evidence into multidisciplinary, individualized care pathways meeting the diverse clinical needs of patients presenting with acute PE.

Massive Embolism: Knife versus PCI

Pulmonary embolism is the third most common cardiovascular syndrome with an estimated up to 25% of patients presenting with sudden death. For those who survive, a mainstay of management for patients with hemodynamic stability is anticoagulation; however, recommendations and options are rapidly changing for patients with submassive or massive pulmonary embolism with hemodynamic instability. Catheter-based and surgical approaches offer efficacious management options for unstable patients or patients with contraindications to anticoagulation; however, both approaches have inherent benefits and risk. This article seeks to offer a brief review on the recommendations and options for management of pulmonary embolism from both surgical and catheter-based perspectives.

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.

Progress in interventional radiology treatment of pulmonary embolism: A brief review

Pulmonary embolism represents a common life-threatening condition. Prompt identification and treatment of this pathological condition are mandatory. In cases of massive pulmonary embolism and hemodynamic instability or right heart failure, interventional radiology treatment for pulmonary embolism is emerging as an alternative to medical treatment (systemic thrombolysis) and surgical treatment. Interventional radiology techniques include percutaneous endovascular catheter directed therapies as selective thrombolysis and thrombus aspiration, which can prove useful in cases of failure or infeasibility of medical and surgical approaches.

Pharmacological and interventional management of pulmonary embolism: where do we stand?

As the third most common cardiovascular disease, pulmonary embolism (PE) has an uptrending incidence and mortality, resulting in significant healthcare expenditure. Risk stratification of acute PE guides management. Although anticoagulation remains the cornerstone management, systemic fibrinolysis and targeted therapeutic approaches, catheter-directed thrombolysis and catheter-based embolectomy are available for high-risk patients. Life-threatening bleeding complications associated with systemic fibrinolysis have restricted its widespread implementation. Catheter-based techniques for intermediate high-risk categories were devised to reduce bleeding complications and improve outcomes. Catheter-directed thrombolysis helps minimize bleeding by way of direct drug delivery. Catheter-based embolectomy mechanically retrieves thrombi without using fibrinolytics. This focused review of medical and interventional management of acute PE provides a highlight of ongoing trials expected to add value to current practice.

Catheter-directed therapy in pulmonary embolism

Acute pulmonary embolism (PE) is a life-threatening condition with high mortality rates and potential long-term sequelae. Systemic thrombolysis has been virtually the only therapeutic option available for patients with hemodynamic instability over decades. Recently, interventional therapy of PE has gained increasing interest. Multiple devices were developed; these include devices for local thrombolysis, thrombus fragmentation, thrombus aspiration, and combined approaches. However, the available evidence is limited to mostly small, nonrandomized studies. In these studies, safety and efficacy data from patients with intermediate or high-risk PE are promising. However, due to the lack of adequately powered randomized trials, interventional treatment of intermediate or high-risk PE cannot be recommended as standard-of-care. The decision on whether and how to perform a catheter-based intervention should therefore be left to the discretion of the local team, depending on the patients' clinical status, bleeding risk, local expertise, and available devices. The implementation of local multidisciplinary PE response teams is recommended by international guidelines to provide the best possible treatment.

Immediate and late impact of reperfusion therapies in acute pulmonary embolism

Haemodynamic instability and right ventricular dysfunction are the key determinants of short-term prognosis in patients with acute pulmonary embolism (PE). Residual thrombi and persistent right ventricular dysfunction may contribute to post-PE functional impairment, and influence the risk of developing chronic thromboembolic pulmonary hypertension. Patients with haemodynamic instability at presentation (high-risk PE) require immediate primary reperfusion to relieve the obstruction in the pulmonary circulation and increase the chances of survival. Surgical removal of the thrombi or catheter-directed reperfusion strategies is alternatives in patients with contraindications to systemic thrombolysis. For haemodynamically stable patients with signs of right ventricular overload or dysfunction (intermediate-risk PE), systemic standard-dose thrombolysis is currently not recommended, because the risk of major bleeding associated with the treatment outweighs its benefits. In such cases, thrombolysis should be considered only as a rescue intervention if haemodynamic decompensation develops. Catheter-directed pharmaco-logical and pharmaco-mechanical techniques ensure swift recovery of echocardiographic and haemodynamic parameters and may be characterized by better safety profile than systemic thrombolysis. For survivors of acute PE, little is known on the effects of reperfusion therapies on the risk of chronic functional and haemodynamic impairment. In intermediate-risk PE patients, available data suggest that systemic thrombolysis may have little impact on long-term symptoms and functional limitation, echocardiographic parameters, and occurrence of chronic thromboembolic pulmonary hypertension. Ongoing and future interventional studies will clarify whether ‘safer’ reperfusion strategies may improve early clinical outcomes without increasing the risk of bleeding and contribute to reducing the burden of long-term complications after intermediate-risk PE.

Interventional Therapies for Acute Pulmonary Embolism: Current Status and Principles for the Development of Novel Evidence: A Scientific Statement From the American Heart Association

Pulmonary embolism (PE) represents the third leading cause of cardiovascular mortality. The technological landscape for management of acute intermediate- and high-risk PE is rapidly evolving. Two interventional devices using pharmacomechanical means to recanalize the pulmonary arteries have recently been cleared by the US Food and Drug Administration for marketing, and several others are in various stages of development. The purpose of this document is to clarify the current state of endovascular interventional therapy for acute PE and to provide considerations for evidence development for new devices that will define which patients with PE would derive the greatest net benefit from their use in various clinical settings. First, definitions and limitations of commonly used risk stratification tools for PE are reviewed. An adjudication of risks and benefits of available interventional therapies for PE follows. Next, considerations for optimal future evidence development in this field are presented in the context of the current US regulatory framework. Finally, the document concludes with a discussion of the pros and cons of the rapidly expanding PE response team model of care delivery.

Systemic Thrombolysis for Pulmonary Embolism: Evidence, Patient Selection, and Protocols for Management

Acute pulmonary embolism presents a clinical challenge for optimal risk stratification. Although associated with significant morbidity and mortality at the population level, the spectrum of presentation in an individual patient varies from mild symptoms to cardiac arrest. Treatment options include anticoagulation, systemic thrombolysis, catheter-based interventions, and surgical embolectomy. In this article, an attempt is made to optimally identify patients who, based on available evidence, may benefit from systemic thrombolytic therapy. The clinical efficacy of systemic thrombolysis must be balanced against increased risks of major bleeding and intracranial hemorrhage.

Catheter-directed Thrombolysis for Intermediate-Risk Pulmonary Embolism

Intermediate-risk pulmonary embolism is common and carries a risk of progression to hemodynamic collapse and death. Catheter-directed thrombolysis is an increasingly used treatment option, based largely on the assumptions that it is more efficacious than anticoagulation alone and safer than systemic thrombolysis. In this review, we critically analyze the published data regarding catheter-directed thrombolysis for the treatment of intermediate-risk pulmonary embolism. Catheter-directed thrombolysis reduces right heart strain and lowers pulmonary artery pressures more quickly than anticoagulation alone. The mortality for patients with intermediate-risk pulmonary embolism treated with catheter-directed thrombolysis is low, between 0% and 4%. However, similarly low mortality is seen with anticoagulation alone. Catheter-directed thrombolysis appears to be safer than systemic thrombolysis, and procedural complications are uncommon. Bleeding risk appears to be slightly higher than with anticoagulation alone. Randomized, controlled trials are needed to compare the efficacy and safety of catheter-directed thrombolysis versus anticoagulation for intermediate-risk pulmonary embolism. There is no evidence that catheter-directed thrombolysis decreases the incidence of chronic thromboembolic pulmonary hypertension. There is no evidence from clinical studies that ultrasound-assisted thrombolysis is more effective or safer than standard catheter-directed thrombolysis.

Catheter-based therapies in acute pulmonary embolism

AIMS

To provide a systematic review of catheter-based therapies of acute pulmonary embolism.

METHODS AND RESULTS

Studies published in peer-reviewed journals before February 2017 were included and categorized according to the mechanism of thrombus removal: fragmentation, rheolytic therapy, aspiration or catheter-directed thrombolysis. Strengths, challenges and the level of evidence of each device were evaluated. We found 16 different catheter-based therapies for acute PE; all but one being used off-label. The majority of procedures involve catheter-directed thrombolysis. Aspiration therapy shows promise, but limited data are available. Rheolytic therapy should be used with caution, if at all, due to the high number of associated complications.

CONCLUSIONS

Catheter-based therapies show promise as a treatment for acute PE, though evidence is lacking. Further research into the efficacy and safety of devices is needed.

Treatment of the acute severe pulmonary embolism using endovascular methods

Purpose

To present a single-centre experience with endovascular treatment of patients with severe symptoms secondary to acute pulmonary embolism (PE).

Material and methods

Twenty-five patients were treated due to contraindications or deficient effects of systemic thrombolytic therapy. The patients were treated with a combination of fragmentation and aspiration, only aspiration, or only fragmentation, and with catheter-directed thrombolytic therapy.

Results

The saturation was improved following treatment in all patients, except in one where the procedure could not be completed. There were no immediate or late procedure-related complications.

Conclusions

Endovascular treatment of severe PE is a safe and efficient option in patients with failing effect or contraindication to systemic thrombolysis.

Pulmonary Embolism Response Teams: A Novel Approach for the Care of Complex Patients With Pulmonary Embolism

Pulmonary embolism represents the third most common cause of cardiovascular death in the United States. Reperfusion therapeutic strategies such as systemic thrombolysis, catheter directed therapies, surgical pulmonary embolectomy, and cardiopulmonary support devices are currently available for patients with high- and intermediate-high–risk pulmonary embolism. However, deciding on optimal therapy may be challenging. Pulmonary embolism response teams have been designed to facilitate multidisciplinary decision-making with the goal to improve quality of care for complex cases with pulmonary embolism. Herein, we discuss the current role and strategies on how to leverage the strengths from pulmonary embolism response teams, its possible worldwide adoption, and implementation to improve survival and change the paradigm in the care of a potentially deadly disease.

Acute pulmonary embolism: endovascular therapy

Pulmonary embolism (PE) is a leading cause of morbidity and mortality worldwide. PE is a complex disease with a highly variable presentation and the available treatment options for PE are expanding rapidly. Anticoagulation (AC), systemic lysis, surgery, and catheter-directed thrombolysis (CDT) play important roles in treating patients with PE. Thus, a multidisciplinary approach to diagnosis, risk stratification, and therapy is required to determine which treatment option is best for a given patient with this complex disease.

Interventional Treatment of Pulmonary Embolism

Pulmonary embolism (PE) is a serious and prevalent cause of vascular disease. Nevertheless, optimal treatment for many phenotypes of PE remains uncertain. Treating PE requires appropriate risk stratification as a first step. For the highest-risk PE, presenting as shock or arrest, emergent systemic thrombolysis or embolectomy is reasonable, while for low-risk PE, anticoagulation alone is often chosen. Normotensive patients with PE but with indicia of right heart dysfunction (by biomarkers or imaging) constitute an intermediate-risk group for whom there is controversy on therapeutic strategy. Some intermediate-risk patients with PE may require urgent stabilization, and ≈10% will decompensate hemodynamically and suffer high mortality, though identifying these specific patients remains challenging. Systemic thrombolysis is a consideration, but its risks of major and intracranial hemorrhages rival overall harms from intermediate PE. Multiple hybrid pharmacomechanical approaches have been devised to capture the benefits of thrombolysis while reducing its risks, but there is limited aggregate clinical experience with such novel interventional strategies. One method to counteract uncertainty and generate a consensus multidisciplinary prognostic and therapeutic plan is through a Pulmonary Embolism Response Team, which combines expertise from interventional cardiology, interventional radiology, cardiac surgery, cardiac imaging, and critical care. Such a team can help determine which intervention-catheter-directed fibrinolysis, ultrasound-assisted thrombolysis, percutaneous mechanical thrombus fragmentation, or percutaneous or surgical embolectomy-is best suited to a particular patient. This article reviews these various modalities and the background for each.

Catheter-Directed Therapy for Acute Submassive Pulmonary Embolism: Summary of Current Evidence and Protocols

Treatment of acute submassive pulmonary embolism (PE) with thrombolytic therapy remains an area of controversy. For patients who fail or who have contraindications to systemic thrombolysis, catheter-directed therapy (CDT) may be offered depending on the patient's condition and the available institutional resources to perform CDT. Although various CDT techniques and protocols exist, the most studied method is low-dose catheter-directed thrombolytic infusion without mechanical thrombectomy. This article reviews current protocols and data on the use of CDT for acute submassive pulmonary embolism.

Catheter-directed interventions for pulmonary embolism

Pulmonary embolism (PE), a potentially life-threatening entity, can be treated medically, surgically, and percutaneously. In patients with right ventricular dysfunction (RVD), anticoagulation alone may be insufficient to restore cardiac function. Because of the morbidity and mortality associated with surgical embolectomy, clinical interest in catheter-directed interventions (CDI) has resurged. We describe specific catheter-directed techniques and the evidence supporting percutaneous treatments.