Comparison by controlled clinical trial of streptokinase and heparin in treatment of life-threatening pulmonay embolism

Percutaneous pulmonary thrombectomy with aspiration catheters in patients with high-risk pulmonary embolism and absolute contraindication to systemic thrombolysis

BACKGROUND

High-risk Pulmonary Embolism (PE) mortality remains very high. Systemic thrombolysis is effective but carries significant complications and contraindications related to the hemorrhagic risk. Percutaneous thrombectomy using aspiration catheters may be an alternative in patients with a high bleeding risk.

OBJECTIVE

This study aimed to evaluate the results of catheter-directed thrombectomy using aspiration dedicated catheters in patients with high-risk PE and absolute contraindication to systemic thrombolysis, with specific focus on procedural success, safety, and in-hospital outcomes.

METHODS

A prospective study enrolled all consecutive patients diagnosed with high-risk pulmonary embolism and absolute contraindication to systemic thrombolysis, who underwent percutaneous pulmonary thrombectomy using dedicated aspiration catheters. The study documented the effectiveness and complications of the procedure, as well as patient outcomes at discharge and during the follow-up period.

RESULTS

Thirteen patients underwent percutaneous pulmonary thrombectomy using aspiration dedicated catheters. The procedure was successful for all patients, resulting in hemodynamic and respiratory improvement within the first 24 h. No deaths attributable to cardiovascular or respiratory causes occurred during admission or follow-up. Furthermore, no serious adverse events or complications were reported during the procedure or hospitalization.

CONCLUSIONS

Percutaneous pulmonary thrombectomy with dedicated aspiration catheters in patients with high-risk pulmonary embolism and contraindications to systemic thrombolysis was associated with excellent clinical results and low rate of complications.

A Practical Clinical Approach to Navigate Pulmonary Embolism Management: A Primer and Narrative Review of the Evolving Landscape

Advances in imaging, pharmacological, and procedural technologies have rapidly expanded the care of pulmonary embolism. Earlier, more accurate identification and quantification has enhanced risk stratification across the spectrum of the disease process, with a number of clinical tools available to prognosticate outcomes and guide treatment. Direct oral anticoagulants have enabled a consistent and more convenient long-term therapeutic option, with a greater shift toward outpatient treatment for a select group of low-risk patients. The array of catheter-directed therapies now available has contributed to a more versatile and nuanced armamentarium of treatment options, including ultrasound-facilitated thrombolysis and mechanical thrombectomy. Research into supportive care for pulmonary embolism have explored the optimal use of vasopressors and volume resuscitation, as well as utilization of various devices, including right ventricular mechanical support and extracorporeal membrane oxygenation. Even in the realm of surgery, outcomes have steadily improved in experienced centers. This rapid expansion in diagnostic and therapeutic data has necessitated implementation of pulmonary embolism response teams to better interpret the available evidence, manage the utilization of advanced therapies, and coordinate multidisciplinary care. We provide a narrative review of the risk stratification and management of pulmonary embolism, with a focus on structuralizing the multidisciplinary approach and organizing the literature on new and emerging therapies.

Advancing the management of acute intermediate-high-risk pulmonary embolism: The enduring legacy of Professor Guy Meyer

Only few years after the first report on diagnosing acute pulmonary embolism (PE) with pulmonary angiography, studies began to investigate the effectiveness and safety of thrombolytic therapy for achieving early reperfusion. In 1992, Guy Meyer demonstrated the fast improvement of pulmonary haemodynamics after alteplase administration; this drug has remained the mainstay of thrombolysis for PE over almost 35 years. In the meantime, algorithms for PE risk stratification continued to evolve. The landmark Pulmonary Embolism International Thrombolysis (PEITHO) trial, led by Guy Meyer, demonstrated the clinical efficacy of thrombolysis for intermediate-risk PE, albeit at a relatively high risk of major, particularly intracranial bleeding. Today, systemic thrombolysis plays an only minor role in the real-world treatment of acute PE in the United States and Europe, but major trials are underway to test safer reperfusion regimens. Of those, the PEITHO-3 study, conceived by Guy Meyer and other European and North American experts, is an ongoing randomised, placebo-controlled, double-blind, multinational academic trial. The primary objective is to assess the efficacy of reduced-dose intravenous thrombolytic therapy against the background of heparin anticoagulation in patients with intermediate-high-risk PE. In parallel, trials with similar design are testing the efficacy and safety of catheter-directed local thrombolysis or mechanical thrombectomy. Increasingly, focus is being placed on long-term functional and patient-reported outcomes, including quality of life indicators, as well as on the utilization of health care resources. The pioneering work of Guy Meyer will thus continue to have a major impact on the management of PE for years to come.

Fibrinolytic Agents in Thromboembolic Diseases: Historical Perspectives and Approved Indications

Fibrinolytic agents catalyze the conversion of the inactive proenzyme plasminogen into the active protease plasmin, degrading fibrin within the thrombus and recanalizing occluded vessels. The history of these medications dates to the discovery of the first fibrinolytic compound, streptokinase, from bacterial cultures in 1933. Over time, researchers identified two other plasminogen activators in human samples, namely urokinase and tissue plasminogen activator (tPA). Subsequently, tPA was cloned using recombinant DNA methods to produce alteplase. Several additional derivatives of tPA, such as tenecteplase and reteplase, were developed to extend the plasma half-life of tPA. Over the past decades, fibrinolytic medications have been widely used to manage patients with venous and arterial thromboembolic events. Currently, alteplase is approved by the U.S. Food and Drug Administration (FDA) for use in patients with pulmonary embolism with hemodynamic compromise, ST-segment elevation myocardial infarction (STEMI), acute ischemic stroke, and central venous access device occlusion. Reteplase and tenecteplase have also received FDA approval for treating patients with STEMI. This review provides an overview of the historical background related to fibrinolytic agents and briefly summarizes their approved indications across various thromboembolic diseases.

Safety and efficacy of clot-dissolving therapies for submassive pulmonary embolism: A network meta-analysis of randomized controlled trials

BACKGROUND

Acute pulmonary embolism (PE) is a serious condition that needs quick and effective treatment. Anticoagulation therapy is the usual care for most PE patients but may not work well for higher-risk ones. Thrombolysis breaks the clot and improves blood flow. It can be given systemically or locally. Ultrasound-assisted catheter-directed thrombolysis (USAT) is a new technique that boosts clot-busting drugs. This network meta-analysis compares death, bleeding, and benefits of four treatments in acute submassive PE.

METHODS

We comprehensively searched relevant databases up to July 2023 for RCTs. The outcomes encompassed all-cause mortality, major and minor bleeding, PE recurrence, and hospital stay duration. Bayesian network meta-analysis computed odds ratios (OR) and 95 % CI estimates.

RESULTS

In this network meta-analysis of 23 RCTs involving 2521 PE patients, we found that SCDT had the most favorable performance for mortality, as it had the lowest odds ratio (OR) among the four interventions (OR 5.41e-42; 95 % CI, 5.68e-97, 1.37e-07). USAT had the worst performance for major bleeding, as it had the highest OR among the four interventions (OR 4.73e+04; 95 % CI, 1.65, 9.16e+13). SCDT also had the best performance for minor bleeding, as it had the lowest OR among the four interventions (OR 5.68e-11; 95 % CI, 4.97e-25, 0.386).

CONCLUSION

Our meta-analysis suggests that SCDT is the most effective treatment intervention in improving the risks of All-cause mortality and bleeding. Thrombolytic therapy helps in improving endpoints including the risk of PE recurrence and the duration of hospital stay.

Management of high-risk pulmonary embolism in the emergency department: A narrative review

BACKGROUND

High-risk pulmonary embolism (PE) is a complex, life-threatening condition, and emergency clinicians must be ready to resuscitate and rapidly pursue primary reperfusion therapy. The first-line reperfusion therapy for patients with high-risk PE is systemic thrombolytics (ST). Despite consensus guidelines, only a fraction of eligible patients receive ST for high-risk PE.

OBJECTIVE

This review provides emergency clinicians with a comprehensive overview of the current evidence regarding the management of high-risk PE with an emphasis on ST and other reperfusion therapies to address the gap between practice and guideline recommendations.

DISCUSSION

High-risk PE is defined as PE that causes hemodynamic instability. The high mortality rate and dynamic pathophysiology of high-risk PE make it challenging to manage. Initial stabilization of the decompensating patient includes vasopressor administration and supplemental oxygen or high-flow nasal cannula. Primary reperfusion therapy should be pursued for those with high-risk PE, and consensus guidelines recommend the use of ST for high-risk PE based on studies demonstrating benefit. Other options for reperfusion include surgical embolectomy and catheter directed interventions.

CONCLUSIONS

Emergency clinicians must possess an understanding of high-risk PE including the clinical assessment, pathophysiology, management of hemodynamic instability and respiratory failure, and primary reperfusion therapies.

Catheter-directed thrombolysis compared with systemic thrombolysis and anticoagulation in patients with intermediate- or high-risk pulmonary embolism: systematic review and network meta-analysis

BACKGROUND

Therapeutic options for intermediate- or high-risk pulmonary embolism (PE) include anticoagulation, systemic thrombolysis and catheter-directed thrombolysis (CDT); however, the role of CDT remains controversial. We sought to compare the efficacy and safety of CDT with other therapeutic options using network meta-analysis.

METHODS

We searched PubMed (MEDLINE), Embase, ClinicalTrials.gov and Cochrane Library from inception to Oct. 18, 2022. We included randomized controlled trials and observational studies that compared therapeutic options for PE, including anticoagulation, systemic thrombolysis and CDT among patients with intermediate- or high-risk PE. The efficacy outcome was in-hospital death. Safety outcomes included major bleeding, intracerebral hemorrhage and minor bleeding.

RESULTS

We included data from 44 studies, representing 20 006 patients. Compared with systemic thrombolysis, CDT was associated with a decreased risk of death (odd ratio [OR] 0.43, 95% confidence interval [CI] 0.32-0.57), intracerebral hemorrhage (OR 0.44, 95% CI 0.29-0.64), major bleeding (OR 0.61, 95% CI 0.53-0.70) and blood transfusion (OR 0.46, 95% CI 0.28-0.77). However, no difference in minor bleeding was observed between the 2 therapeutic options (OR 1.11, 95% CI 0.66-1.87). Compared with anticoagulation, CDT was also associated with decreased risk of death (OR 0.36, 95% CI 0.25-0.52), with no increased risk of intracerebral hemorrhage (OR 1.33, 95% CI 0.63-2.79) or major bleeding (OR 1.24, 95% CI 0.88-1.75).

INTERPRETATION

With moderate certainty of evidence, the risk of death and major bleeding complications was lower with CDT than with systemic thrombolysis. Compared with anticoagulation, CDT was associated with a probable lower risk of death and a similar risk of intracerebral hemorrhage, with moderate certainty of evidence. Although these findings are largely based on observational data, CDT may be considered as a first-line therapy in patients with intermediate- or high-risk PE.

PROTOCOL REGISTRATION

PROSPERO - CRD42020182163.

Comparative Efficacy and Safety of Thrombolytic Agents for Pulmonary Embolism: A Bayesian Network Meta-Analysis

BACKGROUND

Thrombolytic agents and anticoagulants are the two classes of medication used in the treatment of acute pulmonary embolism (PE). There is continuous renewal and iteration of thrombolytic agents, and the efficacy and adverse effects of different agents have different effects on PE due to their different mechanisms of action.

OBJECTIVES

The aim of the study was to evaluate the efficacy and safety of different thrombolytic agents in the treatment of all types of acute PE: hemodynamically unstable PE (massive PE) and hemodynamically stable PE (submassive PE and low-risk PE), using a network meta-analysis.

METHODS

A search was conducted of the following databases: PubMed, The Cochrane Library, Embase, and Web of Science to collect randomized controlled trials (RCTs) comparing thrombolytic agents with heparin or other thrombolytic agents in patients with acute PE; the clinical outcomes included patient mortality, recurrent PE, pulmonary artery systolic pressure (PASP) after treatment, and major and minor bleeding. The measurement duration of outcome indicators was the longest follow-up period. Thereafter, a network meta-analysis was performed using a Bayesian network framework.

RESULTS

A total of 29 RCTs (3,067 patients) were included, of which 6 studies (304 patients) were massive PE, 14 studies (2,173 patients) were submassive PE, 1 study (83 patients) included massive and submassive PE, and 8 studies (507 patients) were PE of unknown type. The treatment regimens included thrombolytic therapy (alteplase, reteplase, tenecteplase, streptokinase, and urokinase) and anticoagulant therapy alone. The results showed that the mortality using thrombolytic agents (except tenecteplase) was significantly lower compared with heparin. The recurrence of PE with alteplase was significantly lower compared with heparin (RR = 0.23, 95% CI, 0.04, 0.65). The PASP after using alteplase was significantly lower compared with heparin (mean difference = -11.36, 95% CI, -21.45, -1.56). Compared with heparin, the incidence of minor bleeding associated with tenecteplase was higher (RR = 3.27, 95% CI, 1.36, 7.39); compared with streptokinase, the incidence of minor bleeding associated with tenecteplase was higher (RR = 3.22, 95% CI, 1.01, 11.10).

CONCLUSION

For patients with acute PE, four thrombolytic agents (alteplase, reteplase, streptokinase, and urokinase) appeared to be superior in efficacy compared with anticoagulants alone due to a reduction in mortality and no increase in bleeding risk. Alteplase may be a better choice because it not only reduced mortality but also reduced PE recurrence rate and treated PASP. Tenecteplase did not reduce mortality compared with anticoagulants alone and may not be a good choice of thrombolytic agent due to an increase in minor bleeding compared with streptokinase and anticoagulants alone. Thrombolytic drugs should be rationally selected to optimize the thrombolytic regimen and achieve as good a balance as possible between thrombolysis and bleeding.

A novel device for lower leg intermittent pneumatic compression synchronized with active ankle exercise for prevention of deep vein thrombosis

Objective

Intermittent pneumatic compression devices (IPCDs) and active ankle exercises have been shown to be efficacious in preventing venous thromboembolism (VTE) by increasing venous flow velocity and volume. However, IPCDs are expensive and require electricity; therefore, they cannot be used in the event of power loss. We developed a non-powered device that provides lower leg intermittent pneumatic compression synchronized with AAEs (LISA) and compared its efficacy with AAEs alone in increasing the peak velocity in the femoral vein.

Methods

The study population consisted of 20 healthy younger men and 20 healthy older men who performed AAE every 2 s in a sitting posture under four conditions: AAE with LISA (AAE+LISA), AAE alone (AAE), AAE with IPCD, and AAE with a graduated compression stocking.

Results

The PVs under all conditions were significantly higher than those at rest. The PVs in the AAE+LISA condition were significantly higher than those in the AAE alone condition in both younger and older groups (both p < .001).

Conclusions

AAE with LISA significantly increased the PV, suggesting that LISA might be useful for preventing DVT.

Thrombolytics for venous thromboembolic events: a systematic review with meta-analysis

Thrombolytic therapy might reduce venous thromboembolism-related mortality and morbidity, but it could also increase the risk of major bleeding. We systematically reviewed the literature to evaluate the effectiveness and safety of thrombolytics in patients with pulmonary embolism (PE) and/or deep venous thrombosis (DVT). We searched Medline, Embase, and Cochrane databases for relevant randomized controlled trials up to February 2019. Multiple investigators independently screened and collected data. We included 45 studies (4740 participants). Pooled estimates of PE studies indicate probable reduction in mortality with thrombolysis (risk ratio [RR], 0.61; 95% confidence interval [CI], 0.40-0.94) (moderate certainty) and possible reduction in nonfatal PE recurrence (RR, 0.56; 95% CI, 0.35-0.89) (low certainty). Pooled estimates of DVT studies indicate the possible absence of effects on mortality (RR, 0.77; 95% CI, 0.26-2.28) (low certainty) and recurrent DVT (RR, 0.99; 95% CI, 0.56-1.76) (low certainty), but possible reduction in postthrombotic syndrome (PTS) with thrombolytics (RR, 0.70; 95% CI, 0.59-0.83) (low certainty). Pooled estimates of the complete body of evidence indicate increases in major bleeding (RR, 1.89; 95% CI, 1.46-2.46) (high certainty) and a probable increase in intracranial bleeding (RR, 3.17; 95% CI 1.19-8.41) (moderate certainty) with thrombolytics. Our findings indicate that thrombolytics probably reduce mortality in patients with submassive- or intermediate-risk PE and may reduce PTS in patients with proximal DVT at the expense of a significant increase in major bleeding. Because the balance between benefits and harms is profoundly influenced by the baseline risks of critical outcomes, stakeholders involved in decision making would need to weigh these effects to define which clinical scenarios merit the use of thrombolytics.

Advanced therapies for pulmonary embolism

PURPOSE OF REVIEW

Treatment options for managing patients with acute pulmonary embolism are rapidly evolving. In this review, we discuss the supporting evidence and implementation strategies for these advanced therapeutic modalities.

RECENT FINDINGS

We review the recent data supporting systemic and catheter directed thrombolytic therapies, mechanical embolectomy, use of extracorporeal membrane oxygen support, and pulmonary embolism response teams in managing patients with acute pulmonary embolism. We discuss the major professional society recommendations regarding their implementation.

SUMMARY

A review of advanced therapies for pulmonary embolism.

Thrombolytic therapy for pulmonary embolism

BACKGROUND

Thrombolytic therapy is usually reserved for people with clinically serious or massive pulmonary embolism (PE). Evidence suggests that thrombolytic agents may dissolve blood clots more rapidly than heparin and may reduce the death rate associated with PE. However, there are still concerns about the possible risk of adverse effects of thrombolytic therapy, such as major or minor haemorrhage. This is the fourth update of the Cochrane review first published in 2006.

OBJECTIVES

To assess the effects of thrombolytic therapy for acute pulmonary embolism.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 17 August 2020. We undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared thrombolytic therapy followed by heparin versus heparin alone, heparin plus placebo, or surgical intervention for people with acute PE (massive/submassive). We did not include trials comparing two different thrombolytic agents or different doses of the same thrombolytic drug.

DATA COLLECTION AND ANALYSIS

Two review authors (ZZ, QH) assessed the eligibility and risk of bias of trials and extracted data. We calculated effect estimates using the odds ratio (OR) with a 95% confidence interval (CI) or the mean difference (MD) with a 95% CI. The primary outcomes of interest were death, recurrence of PE and haemorrhagic events. We assessed the certainty of the evidence using GRADE criteria.

MAIN RESULTS

We identified three new studies for inclusion in this update. We included 21 trials in the review, with a total of 2401 participants. No studies compared thrombolytics versus surgical intervention. We were not able to include one study in the meta-analysis because it provided no extractable data. Most studies carried a high or unclear risk of bias related to randomisation and blinding. Meta-analysis showed that, compared to control (heparin alone or heparin plus placebo), thrombolytics plus heparin probably reduce both the odds of death (OR 0.58, 95% CI 0.38 to 0.88; 19 studies, 2319 participants; low-certainty evidence), and recurrence of PE (OR 0.54, 95% CI 0.32 to 0.91; 12 studies, 2050 participants; low-certainty evidence). Effects on mortality weakened when six studies at high risk of bias were excluded from analysis (OR 0.71, 95% CI 0.45 to 1.13; 13 studies, 2046 participants) and in the analysis of submassive PE participants (OR 0.61, 95% CI 0.37 to 1.02; 1993 participants). Effects on recurrence of PE also weakened after removing one study at high risk of bias for sensitivity analysis (OR 0.60, 95% CI 0.35 to 1.04; 11 studies, 1949 participants). We downgraded the certainty of evidence to low because of 'Risk of bias' concerns. Major haemorrhagic events were probably more common in the thrombolytics group than in the control group (OR 2.84, 95% CI 1.92 to 4.20; 15 studies, 2101 participants; moderate-certainty evidence), as were minor haemorrhagic events (OR 2.97, 95% CI 1.66 to 5.30; 13 studies,1757 participants; low-certainty evidence). We downgraded the certainty of the evidence to moderate or low because of 'Risk of bias' concerns and inconsistency. Haemorrhagic stroke may occur more often in the thrombolytics group than in the control group (OR 7.59, 95% CI 1.38 to 41.72; 2 studies, 1091 participants). Limited data indicated that thrombolytics may benefit haemodynamic outcomes, perfusion lung scanning, pulmonary angiogram assessment, echocardiograms, pulmonary hypertension, coagulation parameters, composite clinical outcomes, need for escalation and survival time to a greater extent than heparin alone. However, the heterogeneity of the studies and the small number of participants involved warrant caution when interpreting results. The length of hospital stay was shorter in the thrombolytics group than in the control group (mean difference (MD) -1.40 days, 95% CI -2.69 to -0.11; 5 studies, 368 participants). Haemodynamic decompensation may occur less in the thrombolytics group than in the control group (OR 0.36, 95% CI 0.20 to 0.66; 3 studies, 1157 participants). Quality of life was similar between the two treatment groups. None of the included studies provided data on post-thrombotic syndrome or on cost comparison.

AUTHORS' CONCLUSIONS

Low-certainty evidence suggests that thrombolytics may reduce death following acute pulmonary embolism compared with heparin (the effectiveness was mainly driven by one trial with massive PE). Thrombolytic therapy may be helpful in reducing the recurrence of pulmonary emboli but may cause more major and minor haemorrhagic events, including haemorrhagic stroke. More studies of high methodological quality are needed to assess safety and cost effectiveness of thrombolytic therapy for people with pulmonary embolism.

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.

Thrombolytic Therapy in Normotensive Patients with Pulmonary Embolism (Data from the Retrospective Study)

Background. The thrombolytic therapy is absolutely recommended for patients in shock or hypotension because the benefits are clearly outweighing the risks. However, in hemodynamically stable patients, including those with acute right ventricular dysfunction and/or myocardial damage, thrombolysis has a significantly lower evidence level.

Aim. To study the criteria based on which doctors decide to conduct thrombolytic therapy in normotensive patients in real clinical practice according to the retrospective data.

Material and methods. A single-center retrospective cohort study analyzed medical records of patients hospitalized in 2006-2017 with a verified diagnosis of pulmonary embolism (PE) and who had a systolic blood pressure >90 mm Hg at the time of admission.

Results. The present study population included 299 patients with a verified diagnosis of PE from 2006 to 2017 years. Patients were divided into two groups: with thrombolysis (group 1) and without thrombolysis (group 2). Logistic regression analysis showed that age younger than 60 years, the presence of varicose veins of the lower extremities, skin cyanosis, syncope in the debut of PE were independent clinical factors that significantly influence the doctor's decision to perform thrombolysis. Increased troponin I, right ventricular dysfunction, and the severity of PE according to the PESI score showed no significant impact on this decision. In-hospital mortality in the group 2 was 1.9% (5 patients), while there were no deaths in the group 1. But the analysis of the association of thrombolysis with survival was difficult to perform due to the low incidence of deaths and the small number of patients in the group with thrombolysis (odds ratio 0.34; 95% confidence interval 0.03-8.18; р=0.856). No major bleeding was registered in any group.

Conclusion. We were not able to clearly identify independent clinical or instrumental factors that influence the decision to perform thrombolysis in patients with PE outside the framework of evidence-based medicine. Further research is needed.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

Thrombolytic therapy for pulmonary embolism

BACKGROUND

Thrombolytic therapy is usually reserved for patients with clinically serious or massive pulmonary embolism (PE). Evidence suggests that thrombolytic agents may dissolve blood clots more rapidly than heparin and may reduce the death rate associated with PE. However, there are still concerns about the possible risk of adverse effects of thrombolytic therapy, such as major or minor haemorrhage. This is the third update of the Cochrane review first published in 2006.

OBJECTIVES

To assess the effects of thrombolytic therapy for acute pulmonary embolism.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 16 April 2018. We undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared thrombolytic therapy followed by heparin versus heparin alone, heparin plus placebo, or surgical intervention for patients with acute PE. We did not include trials comparing two different thrombolytic agents or different doses of the same thrombolytic drug.

DATA COLLECTION AND ANALYSIS

Two review authors (JY, QH) assessed the eligibility and quality of trials and extracted data. We calculated effect estimates using the odds ratio (OR) with 95% confidence interval (CI) or the mean difference (MD) with 95% CI. We assessed the quality of the evidence using GRADE criteria.

MAIN RESULTS

We identified no new studies for inclusion in this 2018 update. We included in the review 18 trials with a total of 2197 participants. We were not able to include one study in the meta-analysis because it provided no data that we could extract. Most of the studies carried a high risk of bias because of high or unclear risk related to randomisation and blinding. Meta-analysis showed that, compared with heparin alone, or heparin plus placebo, thrombolytics plus heparin can reduce the odds of death (OR 0.57, 95% CI 0.37 to 0.87, 2167 participants, P = 0.01, low-quality evidence) and recurrence of PE (OR 0.51, 95% CI 0.29 to 0.89, 1898 participants, P = 0.02, low-quality evidence). Effects on mortality weakened when we excluded from analysis four studies at high risk of bias (OR 0.66, 95% CI 0.42 to 1.06, 2054 participants, P = 0.08). The incidence of major and minor haemorrhagic events was higher in the thrombolytics group than in the control group (OR 2.90, 95% CI 1.95 to 4.31, 1897 participants, P < 0.001, low-quality evidence; OR 3.09, 95% CI 1.58 to 6.06, 1553 participants, P = 0.001, very low-quality evidence, respectively). We downgraded the quality of the evidence to low or very low because of design limitations, potential influence of pharmaceutical companies, and small sample sizes. Length of hospital stay (mean difference (MD) -0.89, 95% CI -3.13 to 1.34) and quality of life were similar between the two treatment groups. Limited information from a small number of trials indicated that thrombolytics may improve haemodynamic outcomes, perfusion lung scanning, pulmonary angiogram assessment, echocardiograms, pulmonary hypertension, coagulation parameters, clinical outcomes, and survival time to a greater extent than heparin alone. However, the heterogeneity of the studies and the small number of participants involved warrant caution when results are interpreted. Similarily, fewer participants from the thrombolytics group required escalation of treatment. None of the included studies reported on post-thrombotic syndrome or compared the costs of different treatments.

AUTHORS' CONCLUSIONS

Low-quality evidence suggests that thrombolytics reduce death following acute pulmonary embolism compared with heparin. The included studies used a variety of thrombolytic drugs. Thrombolytic therapy may be helpful in reducing the recurrence of pulmonary emboli but may cause major and minor haemorrhagic events and stroke. More high-quality, blinded randomised controlled trials assessing safety and cost-effectiveness of therapies for pulmonary embolism are required.

Contemporary Management of the High-Risk Pulmonary Embolism: The Clot Thickens

Pulmonary embolism (PE) is a common disease process encountered in the acute care setting. It presents on a spectrum of severity with the most severe presentations carrying a substantial risk of morbidity and mortality. In recent years, a wide range of competing treatment strategies have been proposed for the high-risk PE including new catheter-based and extracorporeal techniques, and management has become more challenging. There is currently no consensus as to the optimal approach to treatment. Contemporary management decisions are informed by the balance between the risk of deterioration and the risk of harm from intervention, within the available resources. This review will summarize the current evidence to better inform clinical decision-making in high-risk PE and highlight future directions in management.

Surgical pulmonary embolectomy and catheter-directed thrombolysis for treatment of submassive pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) with preserved hemodynamics but right ventricular dysfunction, classified as submassive PE, carries a high risk of mortality. We report the results for patients who did not qualify for medical therapy and required treatment of submassive PE with surgical pulmonary embolectomy and catheter-directed thrombolysis (CDT).

METHODS

Between October 1999 and May 2015, 133 submassive PE patients underwent treatment with pulmonary embolectomy (71) and CDT (62). A multidisciplinary PE response team helped to determine the most appropriate treatment strategy on a case-by-case basis. The EkoSonic ultrasound-facilitated thrombolysis system (EKOS) was used for CDT, which was introduced in 2010.

RESULTS

The mean age of submassive PE patients was 57.3 years, which included 36.8% females. PE risk factors included previous deep venous thrombosis (46.6%), immobility (36.1%), recent surgery (30.8%), and cancer (22.6%), P < 0.05. The most common indication for advanced treatment was right ventricular strain (42.9%), P = 0.03. The frequency of surgical pulmonary embolectomy remained stable even after incorporating the EKOS procedure into our treatment algorithm, with statistically similar operative mortality. Bleeding was observed in six CDT patients and one pulmonary embolectomy patient (P < 0.05). Follow-up echocardiography was available for 61% of the overall cohort, of whom 76.5% had no residual moderate or severe right ventricular dysfunction.

CONCLUSIONS

Pulmonary embolectomy and CDT are important contemporary advanced treatment options for selected high-risk patients with submassive PE, who do not qualify for medical therapy.

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.

From Acute to Chronic Thromboembolic Disease

After achievement of adequate anticoagulation, the natural history of acute pulmonary emboli ranges from near total resolution of vascular perfusion to long-term persistence of hemodynamically consequential residual perfusion defects. The persistence of perfusion defects is necessary, but not sufficient, for the development of chronic thromboembolic pulmonary hypertension (CTEPH). Approximately 30% of patients have persistent defects after 6 months of anticoagulation, but only 10% of those with persistent defects subsequently develop CTEPH. A number of clinical risk factors including increasing age, delay in anticoagulation from symptom onset, and the size of the initial thrombus have been associated with the persistence of perfusion defects. Likewise, a number of cellular and molecular pathways have been implicated in the failure of thrombus resolution, including impaired fibrinolysis, altered fibrinogen structure and function, increased local or systemic inflammation, and remodeling of the embolic material by neovascularization. Treatment with fibrinolytic agents at the time of initial presentation has not clearly improved the frequency or degree of recovery of pulmonary vascular perfusion. A better understanding of the interplay between clinical risk factors and pathogenic mechanisms may enhance the ability to prevent and treat CTEPH in the future.

Can thrombus age guide thrombolytic therapy?

Venous thrombosis (VT) is a common yet complex clinical condition that has shown minimal alteration in clinical management for decades. It is well known that thrombus evolves structurally over time, with complex changes resulting from the interplay between coagulation factors, cytokines, leukocytes and a myriad of other factors. Our current treatment options are most effective in the acute thrombus, which is composed predominantly of a loose mesh of fibrin and red blood cells (RBCs), making current anticoagulation therapies and thrombolytics quite effective in treatment. Later stages of thrombus are more cellular containing leukocytes, and develop a fibrotic collagenous framework that is more resistant to our current treatments. Understanding the biology of an evolving thrombus will allow us to tailor our treatment and optimize outcomes, as well as focus on novel therapies for the treatment of chronic thrombus. Given the morbidity and mortality of both post thrombotic syndrome (PTS) in patients with deep VT, as well as chronic thromboembolic pulmonary hypertension (CTEPH) in patients with pulmonary embolism (PE), new and innovative therapies must continue to be explored to help prevent these potentially devastating conditions.

Efficacy and safety outcomes of recanalisation procedures in patients with acute symptomatic pulmonary embolism: systematic review and network meta-analysis

Background

We aimed to review the efficacy and safety of recanalisation procedures for the treatment of PE.

Methods

We searched PubMed, the Cochrane Library, EMBASE, EBSCO, Web of Science and CINAHL databases from inception through 31 July 2015 and included randomised clinical trials that compared the effect of a recanalisation procedure versus each other or anticoagulant therapy in patients diagnosed with PE. We used network meta-analysis and multivariate random-effects meta-regression to estimate pooled differences between each intervention and meta-regression to assess the association between trial characteristics and the reported effects of recanalisation procedures versus anticoagulation.

Results

For all-cause mortality, there were no significant differences in event rates between any of the recanalisation procedures and anticoagulant treatment (full-dose thrombolysis: OR 0.60; 95% CI0.36 to 1.01; low-dose thrombolysis: 0.47; 95% CI 0.14 to 1.59; and catheter-associated thrombolysis: 0.31; 95% CI 0.01 to 7.96). Full-dose thrombolysis increased the risk of major bleeding (2.00; 95% CI 1.06 to 3.78) compared with anticoagulation. Catheter-directed thrombolysis was associated with the lowest probability of dying (surface under the cumulative ranking curve (SUCRA), 0.67), followed by low-dose thrombolysis (SUCRA, 0.66) and full-dose thrombolysis (SUCRA, 0.55). Similarly, low-dose thrombolysis was associated with the lowest probability of major bleeding (SUCRA, 0.61), followed by catheter-directed thrombolysis (SUCRA, 0.54) and full-dose thrombolysis (SUCRA, 0.17). The results were similar in sensitivity analyses based on restricting only to studies in haemodynamically stable patients with PE.

Conclusions

In the treatment of PE, recanalisation procedures do not seem to offer a clear advantage compared with standard anticoagulation. Low-dose thrombolysis was associated with the lowest probability of dying and bleeding.

Trial registration number

PROSPERO CRD42015024670.

Intense Triceps Surae Contraction Increases Lower Extremity Venous Blood Flow

Objective

Venous thromboembolism can be prevented by physical prophylaxis, such as active ankle exercise (AAE), in addition to pharmacological treatment. However, the relationship between the intensity of triceps surae (TS) exercise and venous flow is unclear, and physical thromboprophylaxis has not been established for patients with leg cast immobilization. The goals of the current study were to clarify the degree of intensity of TS isotonic contraction required to increase peak blood velocity (PV) in the superficial femoral vein to higher than that at no resistance and to determine if TS isometric contraction can increase PV.

Methods

A prospective, nonrandomized, controlled trial was performed in 20 healthy young adult men. PVs at rest and during one TS isotonic or isometric contraction were measured using Doppler ultrasonography. Isotonic contraction intensity was defined as no resistance with contraction of maximum effort and 25%, 50%, 75%, and 100% of one repetition maximum (1RM). Isometric contraction intensity was defined as 15-35%, 40-60%, 65-85%, and 90-100% of the maximal voluntary contraction.

Results

Isotonic contraction at 75% 1RM (51.4 cm/s [95% CI, 40.1-62.6]) and 100% 1RM (54.9 cm/s [95% CI, 43.1-66.7]) significantly increased PV compared to that with no resistance (41.0 cm/s [95% CI, 32.2-49.8]) (P=0.005, 0.001, respectively). Isometric contraction increased PV significantly at all intensities (all P≤0.002).

Conclusions

Applying resistance at ≥75% 1RM increases venous flow and enhances the effect of AAE with TS isotonic contraction. TS isometric contraction may serve as thromboprophylaxis for patients undergoing leg cast immobilization.

Pulmonary Embolism in 2017: How We Got Here and Where Are We Going?

In the 1970s, both the Urokinase Pulmonary Embolism and Urokinase-Streptokinase Pulmonary Embolism trials began the quest to develop thrombolytic therapy for the treatment of acute massive and submassive pulmonary embolism (PE). The goals of these studies were the immediate reduction in clot burden, restoration of hemodynamic stability, and improved survival. Major bleeding became the major barrier for clinicians to employ these therapies. From 1980s to the present time, a number of studies using recombinant tissue-type plasminogen activator for achieving these same above outcomes were completed but major bleeding continued to remain an adoption barrier. Finally, the concept of bringing the thrombolytic agent into the clot has entered the quest for the Holy Grail in the treatment of PE. This article will review all the major trials using peripheral thrombolysis and provide insight into the need for a team approach to pulmonary care (Pulmonary Embolism Response Team), standardization of pulmonary classification, and the need for trials designed for both short- and long-term outcomes using thrombolysis for selected PE populations.

Randomized trial of inhaled nitric oxide to treat acute pulmonary embolism: The iNOPE trial

BACKGROUND

The study hypothesis is that administration of inhaled nitric oxide (NO) plus oxygen to subjects with submassive pulmonary embolism (PE) will improve right ventricular (RV) systolic function and reduce RV strain and necrosis, while improving patient dyspnea, more than treatment with oxygen alone.

METHODS

This article describes the rationale and protocol for a registered (NCT01939301), nearly completed phase II, 3-center, randomized, double-blind, controlled trial. Eligible patients have pulmonary imaging-proven acute PE. Subjects must be normotensive, and have RV dysfunction on echocardiography or elevated troponin or brain natriuretic peptide and no fibrinolytics. Subjects receive NO plus oxygen or placebo for 24 hours (±3 hours) with blood sampling before and after treatment, and mandatory echocardiography and high-sensitivity troponin posttreatment to assess the composite primary end point. The sample size of N=78 was predicated on 30% more NO-treated patients having a normal high-sensitivity troponin (<14 pg/mL) and a normal RV on echocardiography at 24 hours with α=.05 and β=.20. Safety was ensured by continuous spectrophotometric monitoring of percentage of methemoglobinemia and a predefined protocol to respond to emergent changes in condition. Blinding was ensured by identical tanks, software, and physical shielding of the device display and query of the clinical care team to assess blinding efficacy.

RESULTS

We have enrolled 78 patients over a 31-month period. No patient has been withdrawn as a result of a safety concern, and no patient has had a serious adverse event related to NO.

CONCLUSIONS

We present methods and a protocol for the first double-blinded, randomized trial of inhaled NO to treat PE.

Streptokinase and Heparin in the Treatment of Pulmonary Embolism: A Randomized Comparison

Treatment with streptokinase followed by heparin was compared on a randomized basis with treatment with heparin alone in patients with acute pulmonary embolism. The diagnosis and results of treatment were established by pulmonary angiography. Fifteen patients received streptokinase and 16 received heparin alone. Complications included bleeding and pyrexia in both treatment groups and anaphylaxis in a patient receiving streptokinase. There were three deaths attributed to the disease its treatment. Patients in the strepto kinase group had significantly greater angiographic improvement (P = 0.0125) than those in the heparin group.

Fibrinolysis for Acute Care of Pulmonary Embolism in the Intermediate Risk Patient

Controversy over the role of fibrinolysis in patients with intermediate-risk pulmonary embolism (PE) has persisted because of the lack of adequately sized trials. The PEITHO study now allows a more precise estimate of the risk to benefit ratio of fibrinolysis in these patients. This trial enrolled patients with intermediate-risk PE who were randomized to receive heparin with either tenecteplase or placebo. Fibrinolysis was associated with a significant reduction in the combined end-point of death or hemodynamic decompensation, but also with a significant increase in the risk of major bleeding. The primary efficacy end-point occurred in 2.6 % of the patients in the tenecteplase group and in 5.6 % of the patients in the placebo group (OR, 0.44; 95 % CI, 0.23 to 0.87), conversely, major extracranial bleeding occurred in 6.3 % and 1.2 % in the tenecteplase and placebo groups, respectively (OR, 5.55; 95 % CI, 2.3 to 13.39) and stroke occurred in 2.4 % and in 0.2 % of the patients in the tenecteplase group and in the placebo group, respectively (OR, 12.10; 95 % CI, 1.57 to 93.39). No difference was observed for the risk of death alone and the risk of full-dose thrombolytic therapy outweighs its benefit in patients with intermediate-risk PE. Recent meta-analyses suggest that fibrinolysis may be associated with a slight reduction in overall mortality offset by an increase in major bleeding. Two pilot studies suggest that a reduced dose of fibrinolysis may produce significant hemodynamic improvement with a low risk of major bleeding. These options need to be evaluated in larger studies including patients with a higher risk of adverse outcome than those included in the PEITHO study.

Double Bolus Thrombolysis for Suspected Massive Pulmonary Embolism during Cardiac Arrest

More than 70% of cardiac arrest cases are caused by acute myocardial infarction (AMI) or pulmonary embolism (PE). Although thrombolytic therapy is a recognised therapy for both AMI and PE, its indiscriminate use is not routinely recommended during cardiopulmonary resuscitation (CPR). We present a case describing the successful use of double dose thrombolysis during cardiac arrest caused by pulmonary embolism. Notwithstanding the relative lack of high-level evidence, this case suggests a scenario in which recombinant tissue Plasminogen Activator (rtPA) may be beneficial in cardiac arrest. In addition to the strong clinical suspicion of pulmonary embolism as the causative agent of the patient's cardiac arrest, the extremely low end-tidal CO2 suggested a massive PE. The absence of dilatation of the right heart on subxiphoid ultrasound argued against the diagnosis of PE, but not conclusively so. In the context of the circulatory collapse induced by cardiac arrest, this aspect was relegated in terms of importance. The second dose of rtPA utilised in this case resulted in return of spontaneous circulation (ROSC) and did not result in haemorrhage or an adverse effect.

Thrombolytic therapy for pulmonary embolism

BACKGROUND

Thrombolytic therapy (powerful anticoagulation drugs) is usually reserved for patients with clinically serious or massive pulmonary embolism (PE). Evidence suggests that thrombolytic agents may dissolve blood clots more rapidly than heparin and reduce the death rate associated with PE. However, there are still concerns about the possible risk of adverse effects of thrombolytic therapy, such as major or minor haemorrhages. This is the second update of the Cochrane review first published in 2006.

OBJECTIVES

To assess the effects of thrombolytic therapy in patients with acute pulmonary embolism.

SEARCH METHODS

For this update the Cochrane Vascular Group searched their Specialised Register (last searched September 2014) and the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (last searched Issue 8, 2014). We also searched individual trial collections and private databases, along with bibliographies of relevant articles. We handsearched relevant medical journals.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared thrombolytic therapy followed by heparin versus heparin alone, heparin plus placebo or surgical intervention in patients with acute PE. We did not include trials comparing two different thrombolytic agents or different doses of the same thrombolytic drug.

DATA COLLECTION AND ANALYSIS

Two authors (BD and QH) assessed the eligibility and quality of trials and extracted data.

MAIN RESULTS

We identified 18 trials with a total of 2197 participants for inclusion in the review. We were not able to include one study in the meta-analysis because it had no data to extract. Most of the studies carried a high risk of bias because of high or unclear risk relating to randomisation and blinding. Meta-analysis showed that, compared with heparin alone, or heparin plus placebo, thrombolytics plus heparin can reduce the odds of death (odds ratio (OR) 0.57, 95% confidence interval (CI) 0.37 to 0.87, P = 0.02, low quality evidence) and recurrence of PE (OR 0.51; 95% CI 0.29 to 0.89, P = 0.02, low quality evidence). The effects of death weakened when we excluded four studies at high risk of bias from analysis: OR 0.66, 95% CI 0.42 to 1.06, P = 0.08. The incidence of major and minor haemorrhagic events was higher in the thrombolytics group than in the control group, and this difference was statistically significant (OR 2.90, 95% CI 1.95 to 4.31, P < 0.001, low quality evidence; OR 3.09, 95% CI 1.58 to 6.06, P = 0.001, very low quality evidence, respectively). Length of hospital stay (mean difference (MD) -1.35, 95% CI -4.27 to 1.58) and quality of life were similar between the two treatment groups. Stroke was reported in one study and occurred more often in the thrombolytics group than in the control group, although the confidence interval was wide (OR 12.10, 95% CI 1.57 to 93.39). Limited information from a small number of trials indicated that thrombolytics may improve haemodynamic outcomes, perfusion lung scanning, pulmonary angiogram assessment, echocardiograms, pulmonary hypertension, coagulation parameters, clinical outcomes and survival time to a greater extent than heparin alone. However, the heterogeneity of the studies and small number of participants involved warrant caution when interpreting results. Similarily, fewer patients from the thrombolytics group required escalation of treatment. None of the included studies reported on post-thrombotic syndrome or compared the cost of the different treatments.

AUTHORS' CONCLUSIONS

There is low quality evidence that thrombolytics reduce death following acute pulmonary embolism compared with heparin. Furthermore, thrombolytic therapies included in the review were heterogeneous. Thrombolytic therapy may be helpful in reducing the recurrence of pulmonary emboli but may cause more major and minor haemorrhagic events and stroke. More high quality double blind RCTs assessing safety and cost-effectiveness are required.

Acute phase treatment of venous thromboembolism: advanced therapy. Systemic fibrinolysis and pharmacomechanical therapy

Venous thromboembolism, which encompasses deep-vein thrombosis and acute pulmonary embolism (PE), represents a major contributor to global disease burden worldwide. For patients who present with cardiogenic shock or persistent hypotension (acute high-risk PE), there is consensus that immediate reperfusion treatment applying systemic fibrinolysis or, in the case of a high bleeding risk, surgical or catheter-directed techniques, is indicated. On the other hand, for the large, heterogeneous group of patients presenting without overt haemodynamic instability, the indications for advanced therapy are less clear. The recently updated guidelines of the European Society of Cardiology emphasise the importance of clinical prediction rules in combination with imaging procedures (assessment of right ventricular function) and laboratory biomarkers (indicative of myocardial stress or injury) for distinguishing between an intermediate and a low risk for an adverse early outcome. In intermediate-high-risk PE defined by the presence of both right ventricular dysfunction on echocardiography (or computed tomography) and a positive troponin (or natriuretic peptide) test, the bleeding risks of full-dose fibrinolytic treatment have been shown to outweigh its potential clinical benefits unless clinical signs of haemodynamic decompensation appear (rescue fibrinolysis). Recently published trials suggest that catheter-directed, ultrasound-assisted, low-dose local fibrinolysis may provide an effective and particularly safe treatment option for some of these patients.

Systemic thrombolysis for acute pulmonary embolism

Acute pulmonary embolism is a frequent cause of hospitalization and is associated with a wide range of symptom severity. Anticoagulants are the mainstay of treatment for acute pulmonary embolism; however, in patients with massive or submassive pulmonary embolism, advanced therapy with thrombolytics may be considered. The decision to use thrombolytic therapy for acute pulmonary embolism should be based on careful risk-benefit analysis for each patient, including risk of morbidity and mortality associated with the embolism and risk of bleeding associated with the thrombolytic. Alteplase is currently the thrombolytic agent most studied and with the most clinical experience for this indication, although the most appropriate dose remains controversial, especially in patients with low body weight. When considering thrombolysis, unfractionated heparin is the preferred initial anticoagulant due to its short duration of action and its reversibility should bleeding occur.

Recombinant tissue plasminogen activator for hemodynamically stable patients experiencing an acute pulmonary embolism: a meta-analysis

BACKGROUND

The role of thrombolytic therapy for the initial treatment of hemodynamically stable patients experiencing an acute pulmonary embolism remains controversial.

METHODS AND RESULTS

We performed a meta-analysis of randomized trials comparing between administration of recombinant tissue plasminogen activator (rt-PA) and heparin in hemodynamically stable patients experiencing an acute pulmonary embolism. Seven trials, involving 594 patients, were included in this meta-analysis. Compared with heparin, rt-PA was associated with a non-significant reduction in death (2.75% versus 3.96%; RR 0.69, 95% CI 0.31-1.52, P for heterogeneity=0.520) and recurrent pulmonary embolism (2.13% versus 3.34%; RR 0.70, 95% CI 0.28-1.73), and a non-significant increase in major bleeding (5.15% versus 4.29%; RR 1.06, 95% CI 0.520-2.150). Similar results were found based on a subgroup analysis of patients displaying echocardiographic evidence of right ventricular dysfunction (RVD). In contrast, rt-PA treatment was associated with a significant reduction in escalation of care in trials that also enrolled patients displaying RVD compared with heparin treatment (6.56% versus 19.7%; RR 0.34, 95% CI 0.20-0.65).

CONCLUSION

The currently available data provide no evidence for a benefit of administration of rt-PA compared with heparin for the initial treatment of hemodynamically stable patients experiencing an acute pulmonary embolism. However, rt-PA is partially beneficial specifically among patients displaying RVD.

Intraosseous administration of thrombolytics for pulmonary embolism

BACKGROUND

Massive pulmonary embolism is associated with cardiac dysfunction and ischemia, hemodynamic collapse, and significant potential for death. The American College of Chest Physicians and American College of Emergency Physicians each supports thrombolytic administration to hemodynamically unstable patients with acute pulmonary embolism.

OBJECTIVES

In the resuscitation of patients with massive pulmonary embolism and obstructive shock, difficulty with vascular access can hinder care. Alternative options may facilitate delivery of thrombolytics and enhance patient management.

CASE REPORT

The case presented is a 36-year-old woman with massive pulmonary embolism associated with hemodynamic instability. She was treated with thrombolytics through a tibial intraosseous line.

CONCLUSIONS

To the best of our knowledge, this is the first identified case of a patient not in cardiac arrest in whom thrombolytics were administered via an intraosseous line. Similarly, we believe this is also the first reported case of thrombolytics delivered via an intraosseous line for massive pulmonary embolism in the United States.

Clinical controversies in thrombolytic therapy for the management of acute pulmonary embolism

Acute pulmonary embolism is a common complication in hospitalized patients, spanning multiple patient populations and crossing various therapeutic disciplines. Due to the heterogeneous clinical manifestations, the selection of management strategies for patients with acute pulmonary embolism is a challenge for clinicians, and a nuanced understanding of the relevant literature is required. Previous studies that evaluated thrombolytic therapy in patients with acute pulmonary embolism are limited and controversial. Thus, we sought to identify the clinical controversies related to thrombolytic therapy in acute pulmonary embolism and reviewed the recent literature that impacts clinical practice. To apply these controversies into daily clinical practice and decision making, we provide an overview of risk stratification and assessment of pulmonary embolism. Specific areas of controversies that are discussed relate to the impact of thrombolytic therapy on outcomes, specifically in submassive pulmonary embolism, including mortality, composite primary end points, and intensive care unit length of stay. Other controversies relate to the impact of the patient's sex on outcomes, the most safe and effective thrombolytic dose, optimal administration techniques including infusion duration or concurrent anticoagulation, and therapeutic strategies when thrombolytic therapy is unsuccessful. Despite published guidelines and review articles, select aspects of thrombolytic therapy for the management of pulmonary embolism remain controversial; therefore, clinical practice varies from institution to institution and from practitioner to practitioner. When making decisions about the role of thrombolytic therapy in patients with pulmonary embolism, clinicians must be knowledgeable about areas with limited evidence and the therapy's associated risks. In every situation, practitioners must consider the trajectory of the patient's status and the ability to intervene in an appropriate time frame.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Thrombolytic therapy in unstable patients with acute pulmonary embolism: saves lives but underused

BACKGROUND

Data are sparse and inconsistent regarding whether thrombolytic therapy reduces case fatality rate in unstable patients with acute pulmonary embolism. We tested the hypothesis that thrombolytic therapy reduces case fatality rate in such patients.

METHODS

In-hospital all-cause case fatality rate according to treatment was determined in unstable patients with pulmonary embolism who were discharged from short-stay hospitals throughout the United States from 1999 to 2008 by using data from the Nationwide Inpatient Sample. Unstable patients were in shock or ventilator dependent.

RESULTS

Among unstable patients with pulmonary embolism, 21,390 of 72,230 (30%) received thrombolytic therapy. In-hospital all-cause case fatality rate in unstable patients with thrombolytic therapy was 3105 of 21,390 (15%) versus 23,820 of 50,840 (47%) without thrombolytic therapy (P<.0001). All-cause case fatality rate in unstable patients with thrombolytic therapy plus a vena cava filter was 505 of 6630 (7.6%) versus 4260 of 12,850 (33%) with a filter alone (P<.0001). Case fatality rate attributable to pulmonary embolism in unstable patients was 820 of 9810 (8.4%) with thrombolytic therapy versus 1080 of 2600 (42%) with no thrombolytic therapy (P<.0001). Case fatality rate attributable to pulmonary embolism in unstable patients with thrombolytic therapy plus vena cava filter was 70 of 2590 (2.7%) versus 160 of 600 (27%) with a filter alone (P<.0001).

CONCLUSION

In-hospital all-cause case fatality rate and case fatality rate attributable to pulmonary embolism in unstable patients was lower in those who received thrombolytic therapy. Thrombolytic therapy resulted in a lower case fatality rate than using vena cava filters alone, and the combination resulted in an even lower case fatality rate. Thrombolytic therapy in combination with a vena cava filter in unstable patients with acute pulmonary embolism seems indicated.

Mortality risk assessment and the role of thrombolysis in pulmonary embolism

Acute venous thromboembolism remains a frequent disease, with an incidence ranging between 23 and 69 cases per 100,000 population per year. Of these patients, approximately one-third present with clinical symptoms of acute pulmonary embolism (PE) and two-thirds with deep venous thrombosis (DVT). Recent registries and cohort studies suggest that approximately 10% of all patients with acute PE die during the first 1 to 3 months after diagnosis. Overall, 1% of all patients admitted to hospitals die of acute PE, and 10% of all hospital deaths are PE-related. These facts emphasize the need to better implement our knowledge on the pathophysiology of the disease, recognize the determinants of death or major adverse events in the early phase of acute PE, and most importantly, identify those patients who necessitate prompt medical, surgical, or interventional treatment to restore the patency of the pulmonary vasculature.

Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This article addresses the treatment of VTE disease.

METHODS

We generated strong (Grade 1) and weak (Grade 2) recommendations based on high-quality (Grade A), moderate-quality (Grade B), and low-quality (Grade C) evidence.

RESULTS

For acute DVT or pulmonary embolism (PE), we recommend initial parenteral anticoagulant therapy (Grade 1B) or anticoagulation with rivaroxaban. We suggest low-molecular-weight heparin (LMWH) or fondaparinux over IV unfractionated heparin (Grade 2C) or subcutaneous unfractionated heparin (Grade 2B). We suggest thrombolytic therapy for PE with hypotension (Grade 2C). For proximal DVT or PE, we recommend treatment of 3 months over shorter periods (Grade 1B). For a first proximal DVT or PE that is provoked by surgery or by a nonsurgical transient risk factor, we recommend 3 months of therapy (Grade 1B; Grade 2B if provoked by a nonsurgical risk factor and low or moderate bleeding risk); that is unprovoked, we suggest extended therapy if bleeding risk is low or moderate (Grade 2B) and recommend 3 months of therapy if bleeding risk is high (Grade 1B); and that is associated with active cancer, we recommend extended therapy (Grade 1B; Grade 2B if high bleeding risk) and suggest LMWH over vitamin K antagonists (Grade 2B). We suggest vitamin K antagonists or LMWH over dabigatran or rivaroxaban (Grade 2B). We suggest compression stockings to prevent the postthrombotic syndrome (Grade 2B). For extensive superficial vein thrombosis, we suggest prophylactic-dose fondaparinux or LMWH over no anticoagulation (Grade 2B), and suggest fondaparinux over LMWH (Grade 2C).

CONCLUSION

Strong recommendations apply to most patients, whereas weak recommendations are sensitive to differences among patients, including their preferences.