Predictors of major hemorrhage following fibrinolysis for acute pulmonary embolism

Reduced-Dose Thrombolysis in Acute Pulmonary Embolism A Systematic Review

Pulmonary embolism (PE) is the third-leading cause of cardiovascular mortality and the second-leading cause of death in cancer patients. The clinical efficacy of thrombolysis for acute PE has been proven, yet the therapeutic window seems narrow, and the optimal dosing for pharmaceutical reperfusion therapy has not been established. Higher doses of systemic thrombolysis inevitably associated with an incremental increase in major bleeding risk. To date, there is no high-quality evidence regarding dosing and infusion rates of thrombolytic agents to treat acute PE. Most clinical trials have focused on thrombolysis compared with anticoagulation alone, but dose-finding studies are lacking. Evidence is now emerging that lower-dose thrombolytic administered through a peripheral vein is efficacious in accelerating thrombolysis in the central pulmonary artery and preventing acute right heart failure, with reduced risk for major bleeding. The present review will systematically summarize the current evidence of low-dose thrombolysis in acute PE.

Reduced-Dose Systemic Fibrinolysis in Massive Pulmonary Embolism: A Pilot Study

OBJECTIVE

Severe pulmonary embolism (PE) has a high mortality rate, which can be lowered by thrombolytic therapy (TT). However, full-dose TT is associated with major complications, including life-threatening bleeding. The aim of this study was to explore the efficacy and safety of extended, low-dose administration of tissue plasminogen activator (tPA) on in-hospital mortality and outcomes in massive PE.

METHODS

This was a single-center, prospective cohort trial at a tertiary university hospital. A total of 37 consecutive patients with massive PE were included. A peripheral intravenous infusion was used to administer 25 mg of tPA over 6 hours. The primary endpoints were in-hospital mortality, major complications, pulmonary hypertension, and right ventricular dysfunction. The secondary endpoints were 6-month mortality and pulmonary hypertension and right ventricular dysfunction 6 months after the PE.

RESULTS

The mean age of the patients was 68.76±14.54 years. The mean pulmonary artery systolic pressure (PASP; 56.51±7.34 mmHg vs. 34.16±2.81 mmHg, P<0.001) and right/left ventricle diameter (1.37±0.12 vs. 0.99±0.12, P<0.001) decreased significantly after TT. Tricuspid annular plane systolic excursion (1.43±0.33 cm vs. 2.07±0.27 cm, P<0.001), myocardial performance index (0.47±0.08 vs. 0.55±0.07, P<0.001), and systolic wave prime (9.6±2.8 vs. 15.3±2.6) increased significantly after TT. No major bleeding or stroke was observed. There was one in-hospital death and two additional deaths within 6 months. No cases of pulmonary hypertension were identified during follow-up.

CONCLUSION

The results of this pilot study suggest that an extended infusion of low-dose tPA is a safe and effective therapy in patients with massive PE. This protocol was also effective in decreasing PASP and restoring right ventricular function.

Long-Term Outcomes of Patients With Pulmonary Embolism Managed With Endovascular Therapies Compared to Medical Therapy

Background

Guidelines on the management of acute pulmonary embolism (PE) recommend consideration of endovascular therapies (EVT) for patients at intermediate-high risk. However, long-term data on the outcomes of patients after EVT as compared to medical therapy is lacking. This study aimed to compare outcomes of patients receiving EVT as compared to medical therapy alone at 3 to 6 months.

Methods

In this single-center, retrospective cohort study, 190 patients with PE underwent evaluation for presence of right ventricular (RV) dysfunction by transthoracic echocardiogram, residual perfusion defects on ventilation-perfusion scanning, and functional capacity by 6-minute walk distance (6MWD) at 3 to 6 month follow-up.

Results

Fifty-eight (31%) patients received EVT for the management of their acute PE. At follow-up (median 120 [97-170] days), 71% of patients who received EVT had normalization of RV function compared with only 34% of patients who received medical therapy alone (P < .001). Patients who received EVT had a significantly greater increase in their estimated glomerular filtration rate (P = .001), decrease in N-terminal proB-type natriuretic peptide (P = .003), and decrease in hemoglobin values (P = .018). Patients with intermediate-high to high risk PE who received EVT had significantly greater distance achieved on their 6MWD as compared to those who received medical therapy alone (P = .025).

Conclusions

Patients with acute PE who received EVT plus medical therapy were more likely to achieve normalization of RV dysfunction at 3 to 6 month follow-up compared to patients who received medical therapy alone. These data suggest that EVT is an effective therapy option for acute PE in intermediate-high and high risk patients with potential durable long-term benefits.

The spatial ventricular gradient is associated with adverse outcomes in acute pulmonary embolism

BACKGROUND

The spatial ventricular gradient (SVG) is a vectorcardiographic measurement that reflects cardiac loading conditions via electromechanical coupling.

OBJECTIVES

We hypothesized that the SVG is correlated with right ventricular (RV) strain and is prognostic of adverse events in patients with acute pulmonary embolism (PE).

METHODS

Retrospective, single-center study of patients with acute PE. Electrocardiogram (ECG), imaging, and outcome data were obtained. SVG components were regressed on tricuspid annular plane systolic excursion (TAPSE), qualitative RV dysfunction, and RV/left ventricular (LV) ratio. Odds of adverse outcomes (30-day mortality, vasopressor requirement, or advanced therapy) after PE were regressed on demographics, RV/LV ratios, traditional ECG signs of RV dysfunction, and SVG components using a logit model.

RESULTS

ECGs from 317 patients (48% male, age 63.1 ± 16.6 years) with acute PE were analyzed; 36 patients (11.4%) experienced an adverse event. Worse RV hypokinesis, larger RV/LV ratio, and smaller TAPSE were associated with smaller SVG X and Y components, larger SVG Z components, and smaller SVG vector magnitude (p < .001 for all). In multivariable logistic regression, odds of adverse events after PE decreased with increasing SVG magnitude and TAPSE (OR 0.32 and 0.54 per standard deviation increase; p = .03 and p = .004, respectively). Receiver operating characteristic (ROC) analysis showed that, when combined with imaging, replacing traditional ECG criteria with the SVG significantly improved the area under the ROC from 0.70 to 0.77 (p = .01).

CONCLUSION

The SVG is correlated with RV dysfunction and adverse outcomes in acute PE and has a better prognostic value than traditional ECG markers.

An Update on the Management of Acute High-Risk Pulmonary Embolism

Hemodynamic instability and right ventricular (RV) dysfunction are the key determinants of short-term prognosis in patients with acute pulmonary embolism (PE). High-risk PE encompasses a wide spectrum of clinical situations from sustained hypotension to cardiac arrest. Early recognition and treatment tailored to each individual are crucial. Systemic fibrinolysis is the first-line pulmonary reperfusion therapy to rapidly reverse RV overload and hemodynamic collapse, at the cost of a significant rate of bleeding. Catheter-directed pharmacological and mechanical techniques ensure swift recovery of echocardiographic parameters and may possess a better safety profile than systemic thrombolysis. Further clinical studies are mandatory to clarify which pulmonary reperfusion strategy may improve early clinical outcomes and fill existing gaps in the evidence.

Fixed-Dose Ultrasound-Assisted Catheter-Directed Thrombolysis for Acute Pulmonary Embolism Associated with COVID-19

Background. Fixed-dose ultrasound-assisted catheter-directed thrombolysis (USAT) rapidly improves hemodynamic parameters and reverses right ventricular dysfunction caused by acute pulmonary embolism (PE). The effectiveness of USAT for acute PE associated with coronavirus disease 2019 (COVID-19) is unknown. Methods and results. The study population of this cohort study consisted of 36 patients with an intermediate-high- or high-risk acute PE treated with a fixed low-dose USAT protocol (r-tPA 10–20 mg/15 h). Of these, 9 patients tested positive for COVID-19 and were age–sex-matched to 27 patients without COVID-19. The USAT protocol included, beyond the infusion of recombinant tissue plasminogen activator, anti-Xa-activity-adjusted unfractionated heparin therapy (target 0.3–0.7 U/mL). The study outcomes were the invasively measured mean pulmonary arterial pressure (mPAP) before and at completion of USAT, and the National Early Warning Score (NEWS), according to which more points indicate more severe hemodynamic impairment. Twenty-four (66.7%) patients were men; the mean age was 67 ± 14 years. Mean ± standard deviation mPAP decreased from 32.3 ± 8.3 to 22.4 ± 7.0 mmHg among COVID-19 patients and from 35.4 ± 9.7 to 24.6 ± 7.0 mmHg among unexposed, with no difference in the relative improvement between groups (p = 0.84). Within 12 h of USAT start, the median NEWS decreased from six (Q1–Q3: 4–8) to three (Q1–Q3: 2–4) points among COVID-19 patients and from four (Q1–Q3: 2–6) to two (Q1–Q3: 2–3) points among unexposed (p = 0.29). One COVID-19 patient died due to COVID-19-related complications 14 days after acute PE. No major bleeding events occurred. Conclusions. Among patients with COVID-19-associated acute PE, mPAP rapidly decreased during USAT with a concomitant progressive improvement of the NEWS. The magnitude of mPAP reduction was similar in patients with and without COVID-19.

Short-term effects of fibrinolytic therapy on the hemodynamic parameters of patients with intermediate- and high-risk pulmonary embolism

Objective

We aimed to determine the effect of fibrinolytic therapy on hemodynamic parameters at 4 hours after treatment and bleeding complications in patients with intermediate- and high-risk pulmonary embolism.

Methods

This single-center, retrospective, cohort study included patients with intermediate- and high-risk pulmonary embolism treated with fibrinolytics. Their demographic and clinical characteristics, complications, and vital signs at the initiation of and 4 hours after fibrinolytic therapy were evaluated. The primary outcome was the change in the patients’ vital signs at 4 hours after fibrinolytic therapy, compared by the Mann-Whitney U-test.

Results

Seventy-nine patients were included in this study. The systolic and diastolic blood pressures of the high-risk group at 4 hours after fibrinolytic therapy were higher than those at the initiation of fibrinolytic therapy (80 mmHg vs. 99 mmHg, P = 0.029; 49 mmHg vs. 67 mmHg, P = 0.011, respectively). In the intermediate-risk group, the oxygen saturation increased (94% vs. 96%, P = 0.004) and pulse rate decreased (104 beats/min vs. 91 beats/min, P < 0.001).

Conclusion

Blood pressure at 4 hours after fibrinolytic therapy increased in patients with high-risk pulmonary embolism. Also, oxygen saturation and pulse rate improved in intermediate-risk patients.

Ultrasound-accelerated thrombolysis in high-risk perioperative pulmonary embolism: two case reports and review of literature

Introduction

Treatment of high-risk pulmonary embolism (PE) in perioperative patients remains challenging. Systemic thrombolysis is associated with a high risk of major bleedings and intracranial haemorrhage. High mortality rates are reported for open pulmonary embolectomy. Therefore, postoperative surgical patients may benefit substantially from catheter-directed ultrasound-accelerated thrombolysis (USAT).

Case presentation

We report two cases of high-risk perioperative PE. Both patients developed severe haemodynamic instability leading to cardiac arrest. After the implantation of a veno-arterial extracorporeal membrane oxygenation (ECMO), they were both successfully treated with USAT. Adequate improvement of right ventricular function was achieved; thus, ECMO could be successfully weaned after 3 and 4 days, respectively. Both patients showed favourable outcomes and could be discharged to rehabilitation.

Conclusion

Current guidelines on treatment of PE offer no specific therapies for perioperative patients with high-risk PE. However, systemic thrombolysis is often excluded due to the perioperative setting and the risk of major bleeding. Catheter-directed thrombolysis was shown to utilise less thrombolytic agent while obtaining comparable thrombolytic effects. The risk for major bleeding (including intracranial haemorrhage) is also significantly lowered. Until further trials determining the value of adopted treatment strategies of high-risk PE in perioperative patients are available, USAT should be considered in similar cases.

Catheter directed compared to systemically delivered thrombolysis for pulmonary embolism: a systematic review and meta-analysis

To compare the efficacy and safety of systemic and catheter directed thrombolysis for patients with pulmonary embolism. Pubmed and Cochrane Central Register of Controlled Trials were systematically searched from inception to May 31st 2020 to identify relevant studies. Outcomes of interest were in-hospital mortality and major bleeding including intracranial hemorrhage. We included 8 observational studies comprising 11,932 patients with PE. Catheter directed thrombolysis was associated with lower in-hospital mortality [RR 0.52; 95% confidence interval (CI) 0.40-0.68]. Although there was no difference in major bleeding by treatment strategy (RR 0.80; 95% CI 0.37-1.76), intracranial hemorrhage was lower in patients receiving catheter directed therapy (RR 0.66; 95% CI, 0.47-0.94).The certainty in these estimates was low. Non-randomized studies suggest that catheter directed delivery of thrombolytic therapy may be associated with lower in-hospital mortality and intracranial hemorrhage rates. These results may help inform management strategies for health care and pulmonary embolism response teams (PERT) involved in the management of high risk patients with massive or submassive pulmonary emboli.

Treatment of acute pulmonary embolism using rheolytic thrombectomy

BACKGROUND

The AngioJet rheolytic thrombectomy (ART) system can quickly fragment and aspirate thrombi according to Bernoulli's principle.

AIMS

This retrospective study aimed to evaluate the therapeutic effects of the ART system in treating severe acute pulmonary embolism (APE), including high-risk pulmonary embolism (HR-PE) and intermediate-high-risk pulmonary embolism (IHR-PE).

METHODS

Forty-four APE patients (21 HR-PE and 23 IHR-PE) were enrolled and underwent pulmonary ART using the 6 Fr Solent Omni AngioJet device. Nineteen patients were diagnosed with APE and lower extremity deep venous thrombosis (LEDVT), and underwent thrombectomy of APE and LEDVT simultaneously using ART. All patients also received local thrombolysis with urokinase.

RESULTS

The results showed that the mean length of stay in intensive care units was 2.4±1.9 days. Significant improvements in clinical, haemodynamic and angiographic parameters were observed in both groups; the improvements in shock index, PaO2, and angiographic parameters were more obvious in the IHR-PE group. Six of the 44 patients died in hospital. During the follow-up, 35 of 38 patients were functioning well and no recurrence of APE was observed.

CONCLUSIONS

Pulmonary ART plus local thrombolysis of the pulmonary artery for HR-PE or IHR-PE is feasible and appears to be safe. Further studies are warranted to investigate comparative efficacy compared to existing treatments.

Use of fibrinolytics for the management of massive pulmonary embolism in a patient with a history of subdural hemorrhage

INTRODUCTION

Management of massive pulmonary embolism in patients with hemodynamic instability encompasses the use of fibrinolytics. Use of fibrinolytic therapy is currently recommended in this patient population by ACCP, AHA, and EHA if treatment benefit outweighs the risk of bleeding. There is currently no data challenging or exploring the risk of using fibrinolytic therapy for the management of massive PE in patients with a history of intracranial hemorrhage.

CASE PRESENTATION

A 38-year old female with suspected massive pulmonary embolism was admitted with a chief complaint of chest pain and right leg pain. Shortly after a confirmatory CT of bilateral PE, the patient had multiple cardiac arrests along with severe shock that led to a general agreement among the team to proceed with IV and then catheter-directed TPA as well as thrombectomy. Following fibrinolytic therapy, the patient was started on a heparin drip along with epinephrine for hemodynamic support. CT chest angiography showed the resolution of emboli following treatment with the fibrinolytic agent. CT of the head taken approximately 24 h post tPA initiation was used to rule out intracranial hemorrhage or other complications resulting from tPA administration.

CONCLUSION

In patients with a history of intracranial hemorrhage, catheter guided fibrinolytic and thrombectomy may be effective treatment options of massive pulmonary embolism.

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.

Thrombolysis of Pulmonary Emboli via Endobronchial Ultrasound-Guided Transbronchial Needle Injection

BACKGROUND

Endobronchial ultrasound-guided transbronchial needle injection (EBUS-TBNI) is a novel technique for treating peribronchial targets. The aim of this study was to evaluate preliminary feasibility of thrombolysis of pulmonary emboli via EBUS-TBNI.

METHODS

Yorkshire pigs (30-48 kg) were anesthetized and mechanically ventilated. Pre-formed autologous clots were injected sequentially into bilateral lower pulmonary arteries in bilateral models (PE1 and PE2, respectively) or into 1 side in unilateral models using a 21-gauge EBUS-TBNA needle under EBUS guidance. In the bilateral model, 2 hours after clot injection either 25 mL of tissue-plasminogen activator (t-PA; 1mg/mL) or distilled water were administered into each embolus via 25-gauge EBUS-TBNA needle. In the unilateral model, 25 mg t-PA was administered intravenously. Hemodynamic parameters were monitored continuously, and clot dissolved volume was evaluated by EBUS 30 minutes post-treatment administration.

RESULTS

All clots (6.1 ± 1.7 mL) were successfully injected as documented by EBUS Doppler imaging. Clot injection in the bilateral model (n = 6) increased pulmonary arterial pressure (mm Hg: Baseline 19.2 ± 5.9 vs PE1: 26.7 ± 9.1, P = .005 vs PE2 29.9 ± 7.1, P = .0007). After t-PA TBNI in the bilateral model (n = 6), pulmonary arterial pressure at 30 minutes post-injection showed improvement (mm Hg: PE2 29.9 ± 7.1 vs post-t-PA 24.4 ± 3.9, P = .0283). Treatment with t-PA TBNI demonstrated superior clot dissolution at 30 minutes post-treatment (dissolved mm³: t-PA TBNI 625.4 ± 156.6 vs t-PA intravenously: 181.6 ± 94.3, P = .0003 vs distilled water TBNI 42.5 ± 33.0, P < .0001). There were no complications.

CONCLUSIONS

EBUS-guided transbronchial thrombolysis may be a feasible approach for treating central pulmonary emboli.

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.

Catheter-directed therapy for acute pulmonary embolism: navigating gaps in the evidence

Systemic thrombolysis for acute pulmonary embolism (PE) reduces the risk of death and cardiovascular collapse but is associated with an increased rate of bleeding. The desire to minimize the risk of bleeding events has driven the development of catheter-based strategies for pulmonary reperfusion in PE. These catheter-based strategies utilize lower-dose fibrinolytic regimens or purely mechanical techniques to expedite removal of the embolus. Several devices providing mechanical or suction embolectomy and catheter-directed thrombolysis, with or without facilitation by ultrasound, have been tested. Data are inconsistent regarding the efficacy and safety of mechanical and suction embolectomy. The most comprehensive data on catheter-based techniques stem from trials of ultrasound-facilitated catheter fibrinolysis. Ultrasound-facilitated catheter fibrinolysis relieves right ventricular pressure overload with a lower risk of major bleeding and intracranial haemorrhage than historical rates with systemic fibrinolysis. However, further research is required to determine the optimal application of ultrasound-facilitated catheter fibrinolysis and other catheter-based therapies in patients with acute PE.

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

OBJECTIVES

The aim of this study was to determine the lowest optimal tissue plasminogen activator (tPA) dose and delivery duration using ultrasound-facilitated catheter-directed thrombolysis (USCDT) for the treatment of acute intermediate-risk (submassive) pulmonary embolism.

BACKGROUND

Previous trials of USCDT used tPA over 12 to 24 h at doses of 20 to 24 mg for acute pulmonary embolism.

METHODS

Hemodynamically stable adults with acute intermediate-risk pulmonary embolism documented by computed tomographic angiography were randomized into this prospective multicenter, parallel-group trial. Patients received treatment with 1 of 4 USCDT regimens. The tPA dose ranged from 4 to 12 mg per lung and infusion duration from 2 to 6 h. The primary efficacy endpoint was reduction in right ventricular-to-left ventricular diameter ratio by computed tomographic angiography. A major secondary endpoint was embolic burden by refined modified Miller score, measured on computed tomographic angiography 48 h after initiation of USCDT.

RESULTS

One hundred one patients were randomized, and improvements in right ventricular-to-left ventricular diameter ratio were as follows: arm 1 (4 mg/lung/2 h), 0.40 (24%; p = 0.0001); arm 2 (4 mg/lung/4 h), 0.35 (22.6%; p = 0.0001); arm 3 (6 mg/lung/6 h), 0.42 (26.3%; p = 0.0001); and arm 4 (12 mg/lung/6 h), 0.48 (25.5%; p = 0.0001). Improvement in refined modified Miller score was also seen in all groups. Four patients experienced major bleeding (4%). Of 2 intracranial hemorrhage events, 1 was attributed to tPA delivered by USCDT.

CONCLUSIONS

Treatment with USCDT using a shorter delivery duration and lower-dose tPA was associated with improved right ventricular function and reduced clot burden compared with baseline. The major bleeding rate was low, but 1 intracranial hemorrhage event due to tPA delivered by USCDT did occur.

Meta-Analysis of Catheter Directed Ultrasound-Assisted Thrombolysis in Pulmonary Embolism

Ultrasound-assisted catheter directed thrombolysis (USAT) has been shown to improve hemodynamic function and reduce bleeding complications in patients with acute massive or submassive pulmonary embolism. We performed a meta-analysis to better evaluate the efficacy and safety of USAT. We conducted an extensive literature search in PUBMED, MEDLINE, and EMBASE databases from January 1, 2008 to December 31, 2018. Efficacy outcomes of interest were pulmonary artery systolic pressure, mean pulmonary pressure, ratio of right ventricular to left ventricular diameter, cardiac index, tricuspid annular plane systolic excursion, Miller Index Score, and Qanadli Score. Safety outcomes were in-hospital mortality, long-term mortality, major and minor bleeding complications, and recurrent pulmonary embolism. Meta-analysis was performed using Cochrane Collaboration Review Manager (version 5.1). Effect size was estimated using random effects model, with 95% confidence intervals (CIs). Twenty-eight studies (n = 2,135) met inclusion criteria. Compared with pretreatment parameters, post-USAT was associated with a reduction in the mean Miller Index Score and Qanadli Score by 10.55 (95% CI -12.98 to -8.12) and 15.64 (95% CI -19.08 to -12.20), respectively. Cardiac index and tricuspid annular plane systolic excursion improved by 0.68 L/m² (95% CI 0.49 to 0.87) and 3.68 mm (95% CI 2.43 to 4.93), respectively. Pulmonary artery systolic pressure and mean pulmonary pressure after therapy were reduced by a mean difference of 16.69 mm Hg (95% CI -19.73 to -13.65) and 12.13 mm Hg (95% CI -14.67 to -9.59) respectively. The right ventricular to left ventricular diameter dimension ratio decreased by 0.35 (95% CI -0.40 to -0.30) after therapy. In-hospital mortality in patients who underwent USAT was 2.9%, and total long-term mortality was 4.1%. Major and minor bleeding complications were seen in in 5.4% and 6.0% of patients, respectively. Recurrent events occurred in 0.2% of patients after USAT. In conclusion, USAT is a safe and effective procedure associated with significant hemodynamic and clinical improvement in patients with massive and submassive pulmonary embolism.

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.

Acute Pulmonary Thromboembolism: 14 Years of Surgical Experience

Background

Pulmonary thromboembolism (PTE) is a life-threatening disease with high mortality. This study aimed to assess the outcomes of surgical embolectomy and to clarify the sustained long-term effects of surgery by comparing preoperative, postoperative, and long-term follow-up echocardiography outcomes. Of 22 survivors, 21 were followed up for a mean (median) period of 6.8±5.4 years (4.2 years).

Methods

We retrospectively reviewed 27 surgical embolectomy cases for massive or submassive acute PTE from 2003 to 2016. Immediate and long-term follow-up outcomes of surgical embolectomy were assessed on the basis of 30-day mortality, long-term mortality, postoperative complications, right ventricular systolic pressure, and tricuspid regurgitation grade.

Results

The 30-day and long-term mortality rates were 14.8% (4 of 27) and 4.3% (1 of 23), respectively. Three patients had major postoperative complications, including hypoxic brain damage, acute kidney injury, and endobronchial bleeding, respectively (3.7% each). Right ventricular systolic pressure (median [range], mm Hg) decreased from 62.0 (45.5–78.5) to 31.0 (25.7–37.0, p<0.001). The tricuspid valve regurgitation grade (median [range]) decreased from 1.5 (0.63–2.00) to 0.50 (0.50–1.00, p<0.05). The improvement lasted until the last echocardiographic follow-up.

Conclusion

Surgical embolectomy revealed favorable mortality and morbidity rates in patients with acute massive or submassive PTE, with sustained long-term improvements in cardiac function.

Multimodality Assessment of Right Ventricular Strain in Patients With Acute Pulmonary Embolism

Optimal risk stratification is essential in managing patients with an acute pulmonary embolism (PE). There are limited data evaluating the potential additive value of various methods of evaluation of right ventricular (RV) strain in PE. We retrospectively evaluated RV strain by computed tomography (CT), transthoracic echocardiography (TTE), electrocardiography (ECG), and troponin levels in consecutive hospitalized patients with acute PE (May 2007 to December 2014). Four-hundred and seventy-seven patients met inclusion criteria. RV strain on ECG (odds ratio [OR] 1.9, confidence interval [CI] 1.1 to 3.3; p = 0.03), CT (OR 2.7, CI 1.5 to 4.8, p <0.001), TTE (OR 2.8, CI 1.5 to 5.4, p <0.001), or a positive troponin (OR 2.7, CI 2.0 to 6.9, p <0.001) were associated with adverse events. In patients with ECG, CT, and TTE data, increased risk was only elevated with RV strain on all 3 parameters (OR 4.6, CI 1.8 to 11.3, p <0.001). In all patients with troponin measurements, risk was only elevated with RV strain on all 3 parameters plus a positive troponin (OR 8.8, CI 2.8 to 28.1, p <0.001) and was similar in intermediate-risk PE (OR 11.1, CI 1.2 to 103.8, p = 0.04). In conclusion, in patients with an acute PE and evaluation of RV strain by ECG, CT, and TTE, risk of adverse events is only elevated when RV strain is present on all 3 modalities. Troponin further aids in discriminating high-risk patients. Multimodality assessment of RV strain is identified as a superior approach to risk assessment.

Percutaneous Pulmonary Embolism Thrombectomy and Thrombolysis: Technical Tips and Tricks

Catheter-directed therapy (CDT) is now acknowledged as a treatment option for select patients with acute massive or submassive pulmonary embolism (PE), and more patients are being considered for CDT if there is available expertise. Therefore, interventionalists should be aware of the variety of catheter-based treatment options, specific pitfalls to avoid during therapy, and the appropriate treatment endpoints. This article reviews currently available techniques and protocols for treating acute massive and submassive PE, with tips to safely and successfully perform percutaneous PE interventions.

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.

Management of patients with high-risk pulmonary embolism: a narrative review

High-risk pulmonary embolism (PE) is a life-threatening disorder associated with high mortality and morbidity. Most deaths in patients with shock occur within the first few hours after presentation, and rapid diagnosis and treatment is therefore essential to save patients’ lives. The main manifestations of major PE are acute right ventricular (RV) failure and hypoxia. RV pressure overload is predominantly related to the interaction between the mechanical pulmonary vascular obstruction and the underlying cardiopulmonary status. Computed tomography angiography allows not only adequate visualization of the pulmonary thromboemboli down to at least the segmental level but also RV enlargement as an indicator of RV dysfunction. Bedside echocardiography is an acceptable alternative under such circumstances. Although it does not usually provide a definitive diagnosis or exclude pulmonary embolism, echocardiography can confirm or exclude severe RV pressure overload and dysfunction. Extracorporeal membrane oxygenation support can be an effective procedure in patients with PE-induced circulatory collapse. Thrombolysis is generally accepted in unstable patients with high-risk PE; however, thrombolytic agents cannot be fully administered to patients with a high risk of bleeding. Conversely, catheter-directed treatment is an optimal treatment strategy for patients with high-risk PE who have contraindications for thrombolysis and is a minimally invasive alternative to surgical embolectomy. It can be performed with a minimum dose of thrombolytic agents or without, and it can be combined with various procedures including catheter fragmentation or embolectomy in accordance with the extent of the thrombus on a pulmonary angiogram. Hybrid catheter-directed treatment can reduce a rapid heart rate and high pulmonary artery pressure and can improve the gas exchange indices and outcomes. Surgical embolectomy is also performed in patients with contraindications for or an inadequate response to thrombolysis. Large hospitals having an intensive care unit should preemptively establish diagnostic and therapeutic protocols and rehearse multidisciplinary management for patients with high-risk PE. Coordination with a skilled team comprising intensivists, cardiologists, cardiac surgeons, radiologists, and other specialists is crucial to maximize success.

Understanding haemorrhagic risk following thrombolytic therapy in patients with intermediate-risk and high-risk pulmonary embolism: a hypothesis paper

While systemic intravenous thrombolysis decreases mortality in patients with high-risk pulmonary embolism (PE), it clearly increases haemorrhagic risk. There are many contraindications to thrombolysis, and efforts should aim at selecting those patients who will benefit most, without suffering complications. The current review summarises the evidence for the use of thrombolytic therapy in PE. It clarifies the pathophysiological mechanisms in PE and acute cor pulmonale that increase the risk of bleeding following thrombolysis. It discusses future management challenges, namely tailored drug administration, new treatment monitoring techniques and catheter-directed thrombolysis.

Rationale for catheter directed therapy in pulmonary embolism

Pulmonary embolism (PE) is a widespread health concern associated with major morbidity and mortality. Catheter directed therapy (CDT) has emerged as a treatment option for acute PE adding to the current potential options of systemic thrombolysis or anticoagulation. The purpose of this review is to understand the rationale and indications for CDT in patients with PE. While numerous studies have shown the benefits of systemic thrombolysis compared to standard anticoagulation, these are balanced by the increased risk of major bleeding. With this in mind, CDT has the potential to offer the benefits of systemic thrombolysis and in theory, a reduced risk of bleeding. This article will review current treatment guidelines in both massive and submassive PE evaluating both short and long term benefits. The role of CDT will be highlighted, with an emphasis on efficacy and safety.

Pulmonary embolism with cardiac arrest: a STEMI patient's unexpected course

We describe the successful use and complications of bolus-dose alteplase to treat strongly suspected pulmonary embolism (PE) with cardiac arrest in a patient initially presenting as ST-elevation myocardial infarcation (MI). Case description is followed by a review of the indications, safety, and dosing of systemic thrombolytic therapy for high-risk PE in the emergency department (ED). Diagnostic and therapeutic approach to PE in critically ill patients is also considered, including the potential utility of point-of-care ultrasound (PoCUS) in the ED.

A retrospective review of patients with massive and submassive pulmonary embolism treated with AngioJet rheolytic thrombectomy with decreased complications due to changes in thrombolytic use and procedural modifications

Objectives

A retrospective review of treatment of patients with massive or submassive pulmonary embolism (PE) using AngioJet rheolytic thrombectomy (ART) system with procedural modifications to improve on the previously reported outcomes.

Materials and Methods

Thirteen patients underwent emergent pulmonary artery thrombectomy for massive and submassive PE using ART with pharmacological and procedural modification, in comparison to prior reports. The modifications included the selective use of the Solent Omni AngioJet device in all subjects, distal contrast angiography via the AngioJet catheter before device activation, and limited short run times. Thrombolytic therapy was not used in any patient. Patients were monitored for short- and long-term outcomes. Long-term clinical follow-up and evaluation for persistent pulmonary hypertension with echocardiography was performed.

Results

The pharmacological and procedural modifications resulted in a favorable clinical response without any major complications and without any mortality. Procedure-related anemia (mean hemoglobin drop of 0.49 g/dl) was the only significant minor complication noted. There were no bleeding complications and no transfusion requirement. On a six-month follow-up, there was no mortality, and there were significant reductions in the pulmonary artery pressures.

Conclusion

Major and minor complications were reduced compared to prior reports using ART. A modified ART approach towards treatment of high-risk PE appears promising both in terms of efficacy and safety.

Ultrasound Assisted Catheter-Directed Thrombolysis of Acute Pulmonary Embolism: A Review of Current Literature

Pulmonary embolism continues as a very common and also presumably life-threatening disorder. For affected individuals with intermediate- as well as high-risk pulmonary embolism, catheter-based revascularization procedures have developed a possible substitute for systemic thrombolysis or for surgical embolectomy. Ultrasound-assisted catheter-directed thrombolysis is an innovative catheter-based approach; which is the main purpose of the present review article. Ultrasound-assisted catheter-directed thrombolysis is much more efficacious in reversing right ventricular dysfunction as well as dilatation in comparison to anticoagulation alone in individuals at intermediate risk. However, a direct comparison of ultrasound-assisted thrombolysis with systemic thrombolysis or surgical thrombectomy is not available. Ultrasound-assisted thrombolysis with early intrapulmonary thrombolytic bolus could also be successful in high-risk patients, but unfortunately, data from randomized trials is limited. This review article recapitulates existing information on ultrasound-assisted thrombolysis for acute pulmonary embolism.

Systemic Thrombolysis for Pulmonary Embolism: Who and How

Anticoagulation has been shown to improve mortality in acute pulmonary embolism (PE). Initiation of anticoagulation should be considered when PE is strongly suspected and the bleeding risk is perceived to be low, even if acute PE has not yet been proven. Low-risk patients with acute PE are simply continued on anticoagulation. Severely ill patients with high-risk (massive) PE require aggressive therapy, and if the bleeding risk is acceptable, systemic thrombolysis should be considered. However, despite clear evidence that parenteral thrombolytic therapy leads to more rapid clot resolution than anticoagulation alone, the risk of major bleeding including intracranial bleeding is significantly higher when systemic thrombolytic therapy is administered. It has been demonstrated that right ventricular dysfunction, as well as abnormal biomarkers (troponin and brain natriuretic peptide) are associated with increased mortality in acute PE. In spite of this, intermediate-risk (submassive) PE comprises a fairly broad clinical spectrum. For several decades, clinicians and clinical trialists have worked toward a more aggressive, yet safe solution for patients with intermediate-risk PE. Standard-dose thrombolysis, low-dose systemic thrombolysis, and catheter-based therapy which includes a number of devices and techniques, with or without low-dose thrombolytic therapy, have offered potential solutions and this area has continued to evolve. On the basis of heterogeneity within the category of intermediate-risk as well as within the high-risk group of patients, we will focus on the use of systemic thrombolysis in carefully selected high- and intermediate-risk patients. In certain circumstances when the need for aggressive therapy is urgent and the bleeding risk is acceptable, this is an appropriate approach, and often the best one.

Ultrasound-facilitated, catheter-directed, low-dose fibrinolysis in elderly patients with pulmonary embolism: A SEATTLE II sub-analysis

Elderly patients with acute pulmonary embolism (PE) have higher mortality than non-elderly patients, but receive systemic fibrinolysis less frequently. In this sub-analysis of the SEATTLE II trial, we evaluated the efficacy and safety of ultrasound-facilitated, catheter-directed, low-dose fibrinolysis in elderly patients with submassive and massive PE. We compared patients ⩾65 years old with those <65 years old. Eligible patients had proximal PE and a right ventricular-to-left ventricular (RV/LV) diameter ratio ⩾0.9 on chest computed tomography (CT). The primary efficacy outcome was the change in chest CT-measured RV/LV diameter ratio at 48 hours after procedure initiation. The primary safety outcome was major bleeding within 72 hours. Sixty-two patients were ⩾65 years of age and 88 were <65 years of age. The RV/LV diameter ratio decreased in both groups 48 hours post-procedure, with a mean change of −0.47 in those ⩾65 and −0.39 in those <65 years old, with no difference between groups ( p = 0.31). Major bleeding occurred in nine (15%) of those ⩾65 and in six (7%) of those <65 years old ( p = 0.17). Ultrasound-facilitated, catheter-directed, low-dose fibrinolysis resulted in a similar reduction in RV/LV diameter ratio in elderly patients with massive and submassive PE compared with non-elderly patients.

Risk factors for major bleeding in the SEATTLE II trial

Ultrasound-facilitated, catheter-directed, low-dose fibrinolysis minimizes the risk of intracranial bleeding compared with systemic full-dose fibrinolytic therapy for pulmonary embolism (PE). However, major bleeding is nevertheless a potential complication. We analyzed the 150-patient SEATTLE II trial of submassive and massive PE patients to describe those who suffered major bleeding events following ultrasound-facilitated, catheter-directed, low-dose fibrinolysis and to identify risk factors for bleeding. Major bleeding was defined as GUSTO severe/life-threatening or moderate bleeds within 72 hours of initiation of the procedure. Of the 15 patients with major bleeding, four (26.6%) developed access site-related bleeding. Multiple venous access attempts were more frequent in the major bleeding group (27.6% vs 3.6%; p<0.001). All patients with major bleeding had femoral vein access for device delivery. Patients who developed major bleeding had a longer intensive care stay (6.8 days vs 4.7 days; p=0.004) and longer hospital stay (12.9 days vs 8.4 days; p=0.004). The frequency of inferior vena cava filter placement was 40% in patients with major bleeding compared with 13% in those without major bleeding ( p=0.02). Massive PE (adjusted odds ratio 3.6; 95% confidence interval 1.01-12.9; p=0.049) and multiple venous access attempts (adjusted odds ratio 10.09; 95% confidence interval 1.98-51.46; p=0.005) were independently associated with an increased risk of major bleeding. In conclusion, strategies for improving venous access should be implemented to reduce the risk of major bleeding associated with ultrasound-facilitated, catheter-directed, low-dose fibrinolysis. ClinicalTrials.gov Identifier: NCT01513759; EKOS Corporation 10.13039/100006522.

Catheter-Directed Low-Dose Tissue Plasminogen Activator for Treatment of Right Atrial Thrombus Caused by a Central Venous Catheter

Catheter-related atrial thrombosis is a potentially deadly complication of central venous catheters. Options for treatment include surgical thrombectomy, systemic anticoagulation, and systemic thrombolysis, but the optimal method of treatment remains unknown. We describe a 48-year-old woman with a large right atrial thrombus who was successfully treated with localized recombinant tissue plasminogen activator (tPA). She was treated with an 18-hour infusion of localized low-dose tPA administered through her central venous catheter. The dimensions of the thrombus decreased from 30 × 16 × 22 mm to 10 × 8 × 5 mm after treatment with tPA, corresponding to an associated 96% reduction in thrombus volume. No major bleeding complications were observed. Catheter-directed thrombolysis provides the theoretical advantage of a decreased rate of major bleeding by reducing the exposure to and duration of high-dose systemic thrombolytic therapy. To our knowledge, this is the second case report describing the use of this novel therapy. Although no guidelines for the treatment of atrial thrombosis or consensus on the optimal regimen for catheter-directed thrombolysis (and intensity of concomitant anticoagulation) exist, we believe that this intervention may be a well-tolerated alternative to systemic thrombolysis and surgery in certain patients.

A Prospective, Single-Arm, Multicenter Trial of Ultrasound-Facilitated, Catheter-Directed, Low-Dose Fibrinolysis for Acute Massive and Submassive Pulmonary Embolism: The SEATTLE II Study

OBJECTIVES

This study conducted a prospective, single-arm, multicenter trial to evaluate the safety and efficacy of ultrasound-facilitated, catheter-directed, low-dose fibrinolysis, using the EkoSonic Endovascular System (EKOS, Bothell, Washington).

BACKGROUND

Systemic fibrinolysis for acute pulmonary embolism (PE) reduces cardiovascular collapse but causes hemorrhagic stroke at a rate exceeding 2%.

METHODS

Eligible patients had a proximal PE and a right ventricular (RV)-to-left ventricular (LV) diameter ratio ≥0.9 on chest computed tomography (CT). We included 150 patients with acute massive (n = 31) or submassive (n = 119) PE. We used 24 mg of tissue-plasminogen activator (t-PA) administered either as 1 mg/h for 24 h with a unilateral catheter or 1 mg/h/catheter for 12 h with bilateral catheters. The primary safety outcome was major bleeding within 72 h of procedure initiation. The primary efficacy outcome was the change in the chest CT-measured RV/LV diameter ratio within 48 h of procedure initiation.

RESULTS

Mean RV/LV diameter ratio decreased from baseline to 48 h post-procedure (1.55 vs. 1.13; mean difference, -0.42; p < 0.0001). Mean pulmonary artery systolic pressure (51.4 mm Hg vs. 36.9 mm Hg; p < 0.0001) and modified Miller Index score (22.5 vs. 15.8; p < 0.0001) also decreased post-procedure. One GUSTO (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries)-defined severe bleed (groin hematoma with transient hypotension) and 16 GUSTO-defined moderate bleeding events occurred in 15 patients (10%). No patient experienced intracranial hemorrhage.

CONCLUSIONS

Ultrasound-facilitated, catheter-directed, low-dose fibrinolysis decreased RV dilation, reduced pulmonary hypertension, decreased anatomic thrombus burden, and minimized intracranial hemorrhage in patients with acute massive and submassive PE. (A Prospective, Single-arm, Multi-center Trial of EkoSonic® Endovascular System and Activase for Treatment of Acute Pulmonary Embolism (PE) [SEATTLE II]; NCT01513759).