Hemodynamic effects of double bolus reteplase versus alteplase infusion in massive pulmonary embolism

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.

Thrombolysis vs Anticoagulation: Unveiling the Trade-Offs in Massive Pulmonary Embolism

Massive pulmonary embolism (MPE) is a severe form of venous thromboembolism (VTE) wherein enormous blood clots block the pulmonary arteries, resulting in substantial illness and death. Even with the progress made in diagnostic methods and treatments, the most effective approach for managing MPE is still a topic of considerable discussion. This study examines the delicate equilibrium between thrombolysis and anticoagulation in managing the problematic clinical situation posed by MPE, elucidating the compromises linked to each strategy. The genesis of MPE lies in the pathophysiology of VTE, when blood clots that originate from deep veins in the lower legs or pelvis move to the pulmonary vasculature, leading to an abrupt blockage. This obstruction leads to a series of hemodynamic alterations, such as elevated pulmonary vascular resistance, strain on the right ventricle, and compromised cardiac output, finally resulting in cardiovascular collapse. The seriousness of MPE is commonly categorized according to hemodynamic stability, with significant cases presenting immediate risks to patient survival. Traditionally, heparin has been the primary approach to managing MPE to prevent the spread of blood clots and their movement to other parts of the body. Nevertheless, there have been ongoing discussions regarding the effectiveness of thrombolysis, which entails the immediate delivery of fibrinolytic drugs to remove the blood clot. The use of thrombolysis in managing MPE is being reconsidered because of concerns over bleeding complications and long-term results despite its capacity to resolve the blocking clot quickly. This review rigorously analyzes the current body of evidence, exploring the intricacies of thrombolysis and anticoagulation in MPE. The focus is on evaluating the risk-benefit balance of each treatment option, considering aspects such as the patient's other medical conditions, hemodynamic stability, and potential long-term consequences. This review aims to clarify the complexities of the thrombolysis versus anticoagulation dilemma. It seeks to provide clinicians, researchers, and policymakers with a thorough understanding of the trade-offs in managing MPE. The goal is to facilitate informed decision-making and enhance patient outcomes.

Contemporary Treatment of Pulmonary Embolism: Medical Treatment and Management

Pulmonary embolus (PE) is defined as obstruction of the pulmonary artery or one of its branches by material (e.g., thrombus, tumor, air, or fat) but most commonly due to thrombus originating from the lower extremity deep veins.

We reviewed the current literature describing the optimal medical treatment and management of PE.

Databases (PubMed, the Cochrane Library, Embase, EBSCO, Web of Science, and CINAHL) were searched for relevant studies and guidelines for management of patients with PE.

The initial approach to patients with suspected PE should focus upon stabilizing the patient while further workup for risk stratification is in progress. In most cases, anticoagulation should ideally be started even prior to confirming PE, if risk–benefit regarding suspicion of PE and bleeding risk is favorable.

Once the diagnosis is confirmed, risk stratification will guide further therapies consisting of anticoagulation, thrombolysis, or catheter-directed interventions. Data for initial, long-term, and indefinite anticoagulation, and factors that determine whether or not a patient can be treated in the outpatient setting, are reviewed and discussed.

Neurological Complications of Pulmonary Embolism: a Literature Review

PURPOSE OF REVIEW

The present review discusses in-depth about neurological complications following acute venous thromboembolism (VTE).

RECENT FINDINGS

Intracranial hemorrhage, acute ischemic cerebrovascular events, and VTE in brain tumors are described as central nervous system (CNS) complications of PE, while peripheral neuropathy and neuropathic pain are reported as peripheral nervous system (PNS) sequelae of PE. Syncope and seizure are illustrated as atypical neurological presentations of PE. Mounting evidence suggests higher risk of venous thromboembolism (VTE) in patients with neurological diseases, but data on reverse, i.e., neurological sequelae following VTE, is underexplored. The present review is an attempt to explore some of the latter issues categorized into CNS, PNS, and atypical complications following VTE.

Clinical Outcomes of Intermediate-Risk Pulmonary Embolism Across a Northeastern Health System: A Multi-Center Retrospective Cohort Study

OBJECTIVE

The role of thrombolytic therapy in the management of intermediate-risk pulmonary embolism is controversial. Our objective was to determine clinical outcomes for a population of patients with intermediate-risk pulmonary embolism receiving anticoagulation with and without thrombolytic therapy in a large Northeastern health system.

DESIGN

A retrospective cohort study.

SETTING

ICU and non-ICU settings in 8 hospitals.

PATIENTS

Hemodynamically stable patients with intermediate-risk pulmonary embolism.

INTERVENTIONS

Treatment arms were anticoagulation (AC) alone, AC with low dose intravenous thrombolysis, AC with full-dose intravenous thrombolysis, and AC with ultrasound-assisted, catheter-directed thrombolysis.

MEASUREMENTS AND MAIN RESULTS

In 257 patients, utilizing a Bonferroni corrected P value cutoff of α = 0.003, our data shows no differences in 7 day or 30 day all-cause mortality (α = 0.37 and α = 0.04, respectively) , hospital length of stay (α = 0.31), 7 or 30 readmission rates (α = 0.97 and α = 0.84, respectively), or any major (α = 0.82) or minor bleeding events (α = 0.007) among the four treatment groups. Use of anticoagulation alone was associated with a lower duration of ICU stay (α < 0.001). There was a significant decrease in the secondary outcome of one year all-cause mortality in favor of full dose and catheter-directed thrombolytic treatment (α = 0.003). Pulmonary artery systolic pressure of > 70 mmHg was associated with increased 7-day mortality (OR 7.79, P = 0.048), and systolic blood pressure < 130 (OR 23.0; P = 0.003) and elevated N-terminal pro-B-type natriuretic peptide > 1400 pg/nl (OR 15.33; P = 0.01) were associated with increased 30- day mortality.

CONCLUSIONS

The use of thrombolytic therapy is not associated with a mortality benefit in the first 30 days compared to anticoagulation alone in this patient population and is associated with increased utilization of intensive care unit resources. We advocate for a conservative approach utilizing initial anticoagulation alone in a patient diagnosed with intermediate-risk 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.

Thrombolysis with reteplase in acute pulmonary embolism

Objective

Reteplase (recombinant plasminogen activator) is a mutant of alteplase. It has a longer half-life than its parent molecule and has shown better vessel patency rates in acute myocardial infarction. In this study, we analyzed the efficacy and safety of reteplase in acute pulmonary embolism (PE).

Methods

This observational study included patients with high- and intermediate-risk acute PE, presenting within 14 days of symptom onset. The patients were treated with reteplase, which was given in two bolus doses of 10 U each, 30 min apart, along with intravenous heparin. Patients with hemodynamic compromise (high-risk or massive PE) and normotensive patients with evidence of right ventricular (RV) dysfunction (intermediate-risk or submassive PE) on echocardiography or computed tomography were included in the study. The efficacy outcomes assessed were in-hospital death and improvement of RV function by echocardiography. The safety outcomes were major bleeding, minor bleeding, and ischemic or hemorrhagic stroke during hospitalization.

Results

Of the 40 patients included, 25% were classified as high risk with hemodynamic compromise and 75% were classified as intermediate risk. RV dysfunction was present in all the patients (100%). Concomitant lower extremity deep vein thrombosis was present in 55% of the patients. The mortality rate was 5%. There was significant improvement in RV function and reduction in pulmonary artery systolic pressure and tricuspid regurgitation severity. There was no major bleeding event or stroke, and 7.5% patients had minor extracranial bleeding.

Conclusions

Double-bolus reteplase given with heparin is effective in the treatment of high- and intermediate-risk PE, with minimal risk of bleeding.

Improving fibrinolysis in venous thromboembolism: impact of fibrin structure

Introduction. Fibrinolysis is of key importance in maintaining vessel patency. Impaired fibrinolysis associated with more compact fibrin structure has been shown in patients with venous thromboembolism (VTE), including deep-vein thrombosis and pulmonary embolism (PE). Currently, recombinant or modified plasminogen activators are the only commonly available thrombolytic agents. However, they are fraught with side effects and suboptimal effectiveness. Areas covered. Based on the available literature, the current evidence linking fibrinolysis with VTE and potential therapeutic targets among fibrinolysis proteins are presented. Expert opinion. Prolonged clot lysis time has been reported as a new predictor of first-time and recurrent VTE, including PE. Anticoagulant therapy, including non-vitamin K antagonist oral anticoagulants, has a favorable impact on fibrinolysis in VTE patients. Several VTE risk factors are also related to lower efficiency of fibrinolysis and their treatment improve fibrinolysis, in part by alterations to fibrin properties. There is an increasing number of studies aiming at developing novel profibrinolytic therapeutic agents for treatment of VTE patients, mostly targeting the antifibrinolytic proteins, i.e. antiplasmin, plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor.

Use of reteplase for thrombolysis in patients with massive pulmonary embolism diagnosed by bedside transthoracic echocardiography: A retrospective study of safety and efficacy

Background:

Pulmonary embolism (PE) is a lethal clinical condition requiring immediate systemic thrombolysis to decrease mortality. Reteplase has been extensively used in acute myocardial infarction but studies in massive PE are rare. We have presented here efficacy and safety of reteplase in patients with high risk PE diagnosed on basis of bedside transthoracic echocardiography.

Methods:

This was retrospective study including 20 patients of massive PE undergoing thrombolysis with reteplase. Bedside TTE was used to evaluate presence of RV dysfunction and thrombi in these patients with hemodynamic compromise. Safety and efficacy outcomes were analysed till three months of follow up.

Results:

12 patients (60%) included in the study were males and mean age was 41 ± 19 years. The dyspnoea, chest pain and haemoptysis improved in all patients after thrombolysis. At discharge, RV dilatation normalised, systolic pulmonary artery pressure decreased, systolic blood pressure significantly increased and hypoxemia had completely corrected. Two patients had minor self-limiting bleeding episodes in form of mild haematuria and oral bleeding. During the follow up period of 3 months all patients were clinically stable and there were no bleeding episodes or death. Moreover, there was no recurrence of PE and/or DVT.

Conclusion:

Reteplase is highly efficacious in massive pulmonary embolism and results in rapid clinical improvement. Moreover, it can be safely used without increased risk of significant bleeding or mortality. Although limited by retrospective nature, reteplase appears to be an attractive option for massive PE but large prospective studies are further required.

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.

Efficacy evaluation of reteplase in a novel canine acute pulmonary thromboembolism model developed by minimally invasive surgery and digital subtraction angiography

Purpose

In order to evaluate the thrombolytic effects of reteplase in pulmonary thromboembolism (PTE), we developed a novel canine PTE model. The efficacy of reteplase against PTE in comparison to alteplase was clarified for the first time, and this PTE model could be further applied to studies of novel thrombolytic therapies.

Patients and methods

Twenty-four dogs were divided into four groups: sham operation, vehicle, alteplase, and reteplase. Autologous thrombi/saline were injected into the pulmonary artery, and thrombolytic agents were administrated. Thrombus formation and dissolution were monitored by real-time digital subtraction angiography (DSA), and pulmonary pressures were measured simultaneously. Blood coagulation, blood gas, hematology, and histopathologic examinations were used as subsidiary methods.

Results

The canine PTE model was established with a significant decrease of blood flow and ~75% blocking area. Administration of reteplase (0.6 mg/kg) resulted in effective thrombus dissolution with a recovery of over 80% blood flow, as effective as alteplase (1.6 mg/kg). Correspondingly, the elevated pulmonary systolic, diastolic, and mean arterial pressures declined to the normal level. Blood coagulation was changed by reteplase, with a dramatic elongation of prothrombin time, activated partial thromboplastin time, and thrombin time, even longer than alteplase. In contrast to the vehicle group, no obvious pathological changes were found in the two thrombolytic groups. Hematological, blood biochemical, and blood gas results also indicated that reteplase had no adverse reactions in this PTE model.

Conclusion

Reteplase proved to be an effective and safe therapy for PTE for the first time, and a small dosage of reteplase exerted an efficacy comparable to the routine dosage of alteplase. Our findings indicated the potential of reteplase as clinical treatment against PTE. This technically innovative, stability- and validity-proved canine PTE model developed by minimally invasive surgery and DSA resembled major clinical features. This may further facilitate our understanding of thrombotic disorders and development of prophylactic and therapeutic approaches.

Systemic Thrombolytic Therapy for Massive and Submassive Pulmonary Embolism

OBJECTIVE

To critically evaluate the published literature assessing the safety and efficacy of thrombolytic therapy for massive and submassive pulmonary embolism (PE).

METHODS

A search of human trials in the English-language (September 2017) was conducted through the MEDLINE database using the following terms: PE, tissue plasminogen activator, tenecteplase, and alteplase. 67 unique articles were identified, of which 24 clinical trials discussing clinical outcomes related to administration of either intravenous tenecteplase or alteplase were included.

RESULTS

Thrombolytic therapy with anticoagulation significantly reduced mortality compared to anticoagulation alone in massive PE. In submassive PE, thrombolytics reduced the rate of right ventricular dysfunction and hemodynamic collapse; however, there is an increased risk of major and minor bleeding with no benefit on long-term functional outcomes.

CONCLUSIONS

Patients with massive PE should receive thrombolytics when no major contraindications to therapy exist. Patients with submassive PE at highest risk for progression to hemodynamic instability should receive anticoagulation and be monitored for clinical deterioration. If an imminent risk of hemodynamic instability or cardiac arrest occurs, thrombolytics should be administered if no contraindications exist. Net mortality benefit and risk of bleeding must be considered when deciding to administer thrombolytic therapy in massive or submassive PE.

Ultrasound-Assisted Catheter-Directed Thrombolysis in High-Risk and Intermediate-High-Risk Pulmonary Embolism: Results From a Single-Center Cohort

We present our single-center results on ultrasound-assisted thrombolysis (USAT) in patients with pulmonary embolism (PE) at intermediate high risk (IHR) and high risk (HR). Our study consisted of 75 patients with PE who underwent USAT (60 at IHR and 15 at HR). The median time delay from symptoms to USAT was 5 days. Ultrasound-assisted thrombolysis resulted in improvements in tricuspid annular plane systolic excursion; pulmonary artery (PA) systolic and mean pressures; Qanadli score; right to left ventricle diameter ratio and right to left atrial diameter ratio; and diameters of main, right, and left PA regardless of the baseline risk status ( P < .0001 for all). Death was documented in 4 patients, and major and minor bleeding were noted in 2 and 5 of the patients, respectively. No PE-related event was noted during postdischarge follow-up period of median 310 days. Our study revealed that USAT facilitates the resolution of PA thrombotic burden, recovery of pulmonary hemodynamics, and right heart functions with acceptable rates of procedure-related complications in patients with PE, irrespective of the IHR or HR status.

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.

Bleeding risk with systemic thrombolytic therapy for pulmonary embolism: scope of the problem

Acute pulmonary embolism represents a major complication of venous thromboembolism that is associated with high morbidity and mortality. Guidelines recommend the rapid initiation of anticoagulation and consideration of thrombolytic therapy in select patients, including those with hypotension or at high risk of developing hypotension. Evaluation for thrombolytic therapy should only be considered after assessment of contraindications and risk for major bleeding. The objective of this perspective article is to evaluate the bleeding risk associated with systemic thrombolytic therapy in the management of acute pulmonary embolism and discuss strategies to minimize this risk. Risk stratification of acute pulmonary embolism will be discussed to identify patient populations that warrant specific consideration of risk for major bleeding with thrombolytic therapy. In addition, the incidence, patient-specific risk factors, and pharmacologic characteristics, including concurrent anticoagulation and thrombolytic therapy, will be evaluated in the context of risk for major hemorrhage. Finally, supporting evidence for strategies to minimize risk of hemorrhage, including evaluation of contraindications, weight adjusted dosing, infusion strategy and catheter-directed thrombolytic administration will be evaluated. Despite published guidelines and review articles, select aspects to thrombolytic therapy for the management of pulmonary embolism remain controversial and under recognized, including risk of major hemorrhage. When making decisions about the role of thrombolytic therapy in pulmonary embolism, clinicians must be knowledgeable about the associated risks of thrombolytic therapy and individually evaluate patient risk factors prior to determining appropriate candidacy for thrombolytic therapy. For patients considered to be at high risk of major bleeding, strategies to minimize risk should be considered, including weight-adjusted doses and catheter directed therapy. Additional research is needed specific to the acute pulmonary embolism setting to validate risk factors and strategies to minimize major hemorrhage.

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.

Acute pulmonary embolus: the next frontier in venous thromboembolic interventions

OPINION STATEMENT

Submassive pulmonary embolism (PE) represents a patient population that is under-recognized and under-treated. Recent clinical trials demonstrated the hemodynamic benefit of IV thrombolytic therapy among these patients; however, it came at the cost of a significantly increased risk of major, particularly intracranial, hemorrhage. Catheter-based treatment modalities have garnered considerable clinical interest in recent years. In particular, ultrasound accelerated thrombolysis, a catheter-based technology that enhances the process of thrombolytic delivery into the thrombus, has emerged as a treatment modality with an increasing number of single-center studies, as well as randomized, controlled clinical trials. Results from these experiences are consistent in achieving outcomes of thrombus resolution and hemodynamic recovery with a low dose thrombolytic infusion protocol, but without the high risk of bleeding complications associated with IV thrombolysis. The clinical data will hopefully be impactful to the development of the next edition of the treatment guidelines, in support of overall recommendations for catheter-based interventions. When available and with appropriate expertise, this modality should be considered as the preferred treatment of both massive and submassive PE.

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.

Randomized, Controlled Trial of Ultrasound-Assisted Catheter-Directed Thrombolysis for Acute Intermediate-Risk Pulmonary Embolism

Background—

In patients with acute pulmonary embolism, systemic thrombolysis improves right ventricular (RV) dilatation, is associated with major bleeding, and is withheld in many patients at risk. This multicenter randomized, controlled trial investigated whether ultrasound-assisted catheter-directed thrombolysis (USAT) is superior to anticoagulation alone in the reversal of RV dilatation in intermediate-risk patients.

Methods and Results—

Fifty-nine patients (63±14 years) with acute main or lower lobe pulmonary embolism and echocardiographic RV to left ventricular dimension (RV/LV) ratio ≥1.0 were randomized to receive unfractionated heparin and an USAT regimen of 10 to 20 mg recombinant tissue plasminogen activator over 15 hours (n=30; USAT group) or unfractionated heparin alone (n=29; heparin group). Primary outcome was the difference in the RV/LV ratio from baseline to 24 hours. Safety outcomes included death, major and minor bleeding, and recurrent venous thromboembolism at 90 days. In the USAT group, the mean RV/LV ratio was reduced from 1.28±0.19 at baseline to 0.99±0.17 at 24 hours ( P <0.001); in the heparin group, mean RV/LV ratios were 1.20±0.14 and 1.17±0.20, respectively ( P =0.31). The mean decrease in RV/LV ratio from baseline to 24 hours was 0.30±0.20 versus 0.03±0.16 ( P <0.001), respectively. At 90 days, there was 1 death (in the heparin group), no major bleeding, 4 minor bleeding episodes (3 in the USAT group and 1 in the heparin group; P =0.61), and no recurrent venous thromboembolism.

Conclusions—

In patients with pulmonary embolism at intermediate risk, a standardized USAT regimen was superior to anticoagulation with heparin alone in reversing RV dilatation at 24 hours, without an increase in bleeding complications.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01166997.

Systematic review and meta-analysis for thrombolysis treatment in patients with acute submassive pulmonary embolism

PURPOSE

The aim of this systematic review was to evaluate the efficacy and safety of thrombolytic treatment in patients with submassive pulmonary embolism (PE).

METHODS

An electronic search was carried out based on the databases from MEDLINE, Embase, Science Citation Index (SCI), and the Cochrane Library. We included prospective, randomized, and clinical trials in thrombolysis with heparin alone in adults who had evidence of right ventricular dysfunction and normotension. The main endpoints consist of mortality, recurrent PE, and bleeding risk. The relative risk (RR) and the relevant 95% confidence intervals were determined by the dichotomous variable.

RESULTS

Only seven studies involving 594 patients met the inclusion criteria for further review. The cumulative effect of thrombolysis, compared with intravenous heparin, demonstrated no statistically significant difference in mortality (2.7% versus 4.3%; RR=0.64 [0.29-1.40]; P=0.27) or recurrent PE (2% versus 5%; RR=0.44 [0.19-1.05]; P=0.06). Thrombolytic therapy did not increase major hemorrhage compared with intravenous heparin (4.5% versus 3.3%; RR=1.16 [0.51-2.60]; P=0.73), but it was associated with an increased minor hemorrhage (41% versus 9%; RR=3.91 [1.46-10.48]; P=0.007).

CONCLUSION

Compared with heparin alone, neither mortality nor recurrent PE is reduced by thrombolysis in patients with submassive PE, and it does not reveal an increasing risk of major bleeding. In addition, thrombolysis also produces the increased risk of minor bleeding; however, no sufficient evidence verifies the thrombolytic benefit in this review, because the number of patients enrolled in the trials is limited. Therefore, a large, double-blind clinical trial is required to prove the outcomes of this meta-analysis.

Fixed low-dose ultrasound-assisted catheter-directed thrombolysis for intermediate and high-risk pulmonary embolism

AIMS

No standardized local thrombolysis regimen exists for the treatment of pulmonary embolism (PE). We retrospectively investigated efficacy and safety of fixed low-dose ultrasound-assisted catheter-directed thrombolysis (USAT) for intermediate- and high-risk PE.

METHODS AND RESULTS

Fifty-two patients (65 ± 14 years) of whom 14 had high-risk PE (troponin positive in all) and 38 intermediate-risk PE (troponin positive in 91%) were treated with intravenous unfractionated heparin and USAT using 10 mg of recombinant tissue plasminogen activator per device over the course of 15 h. Bilateral USAT was performed in 83% of patients. During 3-month follow-up, two [3.8%; 95% confidence interval (CI) 0.5-13%] patients died (one from cardiogenic shock and one from recurrent PE). Major non-fatal bleeding occurred in two (3.8%; 95% CI, 0.5-13%) patients: one intrathoracic bleeding after cardiopulmonary resuscitation requiring transfusion, one intrapulmonary bleeding requiring lobectomy. Mean pulmonary artery pressure decreased from 37 ± 9 mmHg at baseline to 25 ± 8 mmHg at 15 h (P < 0.001) and cardiac index increased from 2.0 ± 0.7 to 2.7 ± 0.9 L/min/m(2) (P < 0.001). Echocardiographic right-to-left ventricular end-diastolic dimension ratio decreased from 1.42 ± 0.21 at baseline to 1.06 ± 0.23 at 24 h (n = 21; P < 0.001). The greatest haemodynamic benefit from USAT was found in patients with high-risk PE and in those with symptom duration < 14 days.

CONCLUSION

A standardized catheter intervention approach using fixed low-dose USAT for the treatment of intermediate- and high-risk PE was associated with rapid improvement in haemodynamic parameters and low rates of bleeding complications and mortality.

Successful alteplase bolus administration for a presumed massive pulmonary embolism during cardiopulmonary resuscitation

OBJECTIVE

To describe the case of a patient successfully resuscitated with bolus alteplase for a presumed massive pulmonary embolism (PE) with associated cardiac arrest.

CASE SUMMARY

A 54-year-old man presented to the emergency department for evaluation of syncope following recent open reduction and internal fixation of his ankle. On arrival, his condition rapidly deteriorated and progressed to cardiopulmonary arrest. Because of noncompliance with postoperative thromboprophylaxis, there was high suspicion for PE. Following 40 minutes of advanced cardiac life support, empirical alteplase 50 mg was administered intravenously over 2 minutes with return of spontaneous circulation (ROSC) observed 6 minutes later. The diagnosis of PE using computed tomographic angiography was confirmed after fibrinolytic therapy. Although his hospital course was complicated by a gastrointestinal bleed requiring transfusion, he was discharged neurologically intact.

DISCUSSION

Clinical guidelines recommend fibrinolytic therapy for patients with PE and cardiac arrest. Data from retrospective analyses, case series, and case reports suggest that various fibrinolytic regimens may facilitate ROSC and improve neurologically intact survival without an increased risk of fatal hemorrhage.

CONCLUSION

The choice of fibrinolytic therapy should be based on hospital availability, with prompt initiation of treatment and incorporation of an intravenous bolus. A reasonable treatment regimen is alteplase 0.6 mg/kg (maximum of 50 mg) or fixed dose of alteplase 50 mg given over 2 to 15 minutes. Resuscitation should be continued for at least 30 minutes, or until ROSC, after fibrinolytic initiation to allow time for the medication to work.

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.

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.

Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association

Venous thromboembolism (VTE) is responsible for the hospitalization of >250 000 Americans annually and represents a significant risk for morbidity and mortality. Despite the publication of evidence-based clinical practice guidelines to aid in the management of VTE in its acute and chronic forms, the clinician is frequently confronted with manifestations of VTE for which data are sparse and optimal management is unclear. In particular, the optimal use of advanced therapies for acute VTE, including thrombolysis and catheter-based therapies, remains uncertain. This report addresses the management of massive and submassive pulmonary embolism (PE), iliofemoral deep vein thrombosis (IFDVT),and chronic thromboembolic pulmonary hypertension (CTEPH). The goal is to provide practical advice to enable the busy clinician to optimize the management of patients with these severe manifestations of VTE. Although this document makes recommendations for management, optimal medical decisions must incorporate other factors, including patient wishes, quality of life, and life expectancy based on age and comorbidities. The appropriateness of these recommendations for a specific patient may vary depending on these factors and will be best judged by the bedside clinician.

Pulmonary thromboembolic disease. Clinical management of acute and chronic disease

Pulmonary thromboembolism falls between the areas of pulmonology and cardiology, internal medicine and intensive care, radiology and nuclear medicine, and hematology and cardiothoracic surgery. Depending on their clinical background, physicians faced with a patient with a pulmonary thromboembolism may speak different languages and adopt different treatment approaches. Now, however, there is an opportunity to end the Tower of Babel surrounding pulmonary thromboembolism. There is a growing acknowledgement that the key clinical problems in both acute pulmonary embolism and chronic thromboembolic pulmonary hypertension are linked to right ventricular pressure overload and right ventricular failure. As a result, cardiologists and cardiac intensive care specialists are taking an increasing interest in understanding and combating these conditions. The European Society of Cardiology was the first to elaborate comprehensive clinical practice guidelines for pulmonary thromboembolism and chronic thromboembolic pulmonary hypertension. The task forces involved in producing these guidelines included radiologists, pulmonologists, hematologists, intensive care physicians and surgeons, which ensured that the final document was universally acceptable. The aim of this article was to provide an overview of the epidemiology, risk factors, diagnosis, treatment, prognosis and prevention of acute pulmonary thromboembolism and chronic thromboembolic pulmonary hypertension, while taking into account European Society of Cardiology guidelines and incorporating new evidence where necessary.

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.

Efficacy and safety of 2-hour urokinase regime in acute pulmonary embolism: a randomized controlled trial

Backgrounds

Urokinase (UK) 2 200 U/kg·h for 12 hours infusion(UK-12 h)is an ACCP recommended regimen in treating acute pulmonary embolism (PE). It is unclear whether this dose and time can be reduced further. We compared the efficacy and safety of 20, 000 U/kg for 2 hours (UK-2 h) with the UK-12 h regime in selected PE patients.

Methods

A randomized trial involving 129 patients was conducted. Patients with acute PE were randomly assigned to receive either UK-12 h (n = 70), or UK-2 h (n = 59). The efficacy was determined by the improvement of right heart dysfunction and perfusion defect at 24 h and 14 d post UK treatment. The bleeding incidence, death rate and PE recurrence were also evaluated.

Results

Similarly significant improvements in right heart dysfunction and lung perfusion defects were observed in both groups. Overall bleeding incidents were low in both groups. Major bleeding directly associated with UK infusion occurred in one patient in the UK-2 h group and one in the UK-12 h group. Mortality rates were low, with one reported fatal recurrent in the UK-12 h group and none in the UK-2 h group. When the rate of bleeding, death and PE recurrence were compared separately in the hemodynamic instability and the massive anatomic obstruction subgroups, no significant difference was found.

Conclusions

The UK-2 h regimen exhibits similar efficacy and safety as the UK-12 h regimen for acute PE.

Trial Registration

Clinical trial registered with http://clinicaltrials.gov/ct2/show/NCT00799968 (Identifier: NCT 00799968)

Efficacy and safety of low dose recombinant tissue-type plasminogen activator for the treatment of acute pulmonary thromboembolism: a randomized, multicenter, controlled trial

Background

Optimal dosing of the recombinant tissue-type plasminogen activator (rt-PA) is important in treating pulmonary thromboembolism (PTE). The aim of this study was to compare the efficacy and safety of a 50 mg/2 h rt-PA regimen with a 100 mg/2 h rt-PA regimen in patients with acute PTE.

Methods

A prospective, randomized, multicenter trial was conducted in which 118 patients with acute PTE and either hemodynamic instability or massive pulmonary artery obstruction were randomly assigned to receive a treatment regiment of either rt-PA at 50 mg/2 h (n = 65) or 100 mg/2 h (n = 53). The efficacy was determined by observing the improvements of right ventricular dysfunctions (RVDs) on echocardiograms, lung perfusion defects on ventilation perfusion lung scans, and pulmonary artery obstructions on CT angiograms. The adverse events, including death, bleeding, and PTE recurrence, were also evaluated.

Results

Progressive improvements in RVDs, lung perfusion defects, and pulmonary artery obstructions were found to be similarly significant in both treatment groups. This is true for patients with either hemodynamic instability or massive pulmonary artery obstruction. Three (6%) patients in the rt-PA 100 mg/2 h group and one (2%) in the rt-PA 50 mg/2 h group died as the result of either PTE or bleeding. Importantly, the 50 mg/2 h rt-PA regimen resulted in less bleeding tendency than the 100 mg/2 h regimen (3% vs 10%), especially in patients with a body weight < 65 kg (14.8% vs 41.2%, P = .049). No fatal recurrent PTE was found in either group.

Conclusions

Compared with the 100 mg/2 h regimen, the 50 mg/2 h rt-PA regimen exhibits similar efficacy and perhaps better safety in patients with acute PTE. These findings support the notion that optimizing rt-PA dosing is worthwhile when treating patients with PTE.

Trial registration

clinicaltrials.gov; Identifier: NCT00781378

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 might 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 an update of a Cochrane review first published in 2006.

OBJECTIVES

To assess the effectiveness and safety of thrombolytic therapy in patients with acute PE.

SEARCH STRATEGY

For this update the Cochrane Peripheral Vascular Diseases Review Group searched their Specialised Register (last searched April 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched Issue 2, 2009). We also searched individual trial collections and private databases, along with bibliographies of relevant articles. Relevant medical journals were handsearched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared thrombolytic therapy with placebo or heparin 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 (DB and WQ) assessed the eligibility and quality of trials and extracted data.

MAIN RESULTS

We included eight trials, with a total of 679 patients, in this review. Results between thrombolytics compared with heparin alone or placebo and heparin were similar in terms of: a) death rate: odds ratio (OR) 0.89; 95% confidence interval (CI) 0.45 to 1.78; b) recurrence of pulmonary embolism: OR 0.63; 95% CI 0.33 to 1.20; c) major haemorrhagic events: OR 1.61; 95% CI 0.91 to 2.86; d) minor haemorrhagic events: OR 1.98; 95% CI 0.68 to 5.75.We found no trials comparing thrombolytic therapy to surgical intervention.Using recombinant tissue-type plasminogen activator (rt-PA) and heparin together compared to heparin alone appeared to reduce the need for further treatment for in-hospital events (OR 0.35; 95% CI 0.17 to 0.71).Thrombolytics improved haemodynamic outcomes, perfusion lung scanning, pulmonary angiogram assessment and echocardiograms to a greater extent than heparin alone.

AUTHORS' CONCLUSIONS

Based on the limited evidence found we cannot conclude whether thrombolytic therapy is better than heparin for pulmonary embolism. More double-blind RCTs, with subgroup analysis of patients presenting with haemodynamically stable acute pulmonary embolism compared to those patients with a haemodynamic unstable condition, are required.