Low-Dose Systemic Alteplase (tPA) for the Treatment of Pulmonary Embolism

Redox-responsive peptide-based complex coacervates as delivery vehicles with controlled release of proteinous drugs

Proteinous drugs are highly promising therapeutics to treat various diseases. However, they suffer from limited circulation times and severe off-target side effects. Inspired by active membraneless organelles capable of dynamic recruitment and releasing of specific proteins, here, we present the design of coacervates as therapeutic protocells, made from small metabolites (anionic molecules) and simple arginine-rich peptides (cationic motif) through liquid-liquid phase separation. These complex coacervates demonstrate that their assembly and disassembly can be regulated by redox chemistry, which helps to control the release of the therapeutic protein. A model proteinous drugs, tissue plasminogen activator (tPA), can rapidly compartmentalize inside the complex coacervates, and the coacervates formed from peptides conjugated with arginine-glycine-aspartic acid (RGD) motif (a fibrinogen-derived peptide sequence), show selective binding to the thrombus site and thus enhance on-target efficacy of tPA. Furthermore, the burst release of tPA can be controlled by the redox-induced dissolution of the coacervates. Our proof-of-principle complex coacervate system provides insights into the sequestration and release of proteinous drugs from advanced drug delivery systems and represents a step toward the construction of synthetic therapeutic protocells for biomedical applications.

Advanced Treatment of Hemodynamically Unstable Acute Pulmonary Embolism and Clinical Follow-up

High-risk acute pulmonary embolism (PE), defined as acute PE associated with hemodynamic instability, remains a significant contributor to cardiovascular morbidity and mortality in the United States and worldwide. Historically, anticoagulant therapy in addition to systemic thrombolysis has been the mainstays of medical therapy for the majority of patients with high-risk PE. In efforts to reduce the morbidity and mortality, a wide array of interventional and surgical therapies has been developed and employed in the management of these patients. However, the most recent guidelines for the management of PE have reserved the use of these advanced therapies in scenarios where thrombolytic therapy plus anticoagulation are unsuccessful. This is due largely to the lack of prospective, randomized studies in this population. Stemming from this, the approach to treatment of these patients varies widely depending on institutional experience and resources. Furthermore, morbidity and mortality remain unacceptably high in this population, with estimated 30-day mortality of at least 30%. As such, development of a standardized approach to treatment of these patients is paramount to improving outcomes. Early and accurate risk stratification in conjunction with a multidisciplinary team approach in the form of a PE response team is crucial. With the advent of novel therapies for the treatment of acute PE, in addition to the growing availability of and familiarity with mechanical circulatory support systems, such a standardized approach may now be within reach.

Successful Treatment of Saddle Pulmonary Thromboembolism in 23-Week Preterm Infant

Saddle pulmonary thromboembolism (PTE) is defined as a thromboembolism straddling the bifurcation of the main pulmonary artery trunk and it is rarely seen in extremely low birth weight infants (ELBWI). Saddle PTE is a critical disease that requires urgent treatment. However, the treatment guidelines for ELBWI are not established. We present the case of a 1-day-old preterm infant (gestational age 23 weeks) who showed sudden desaturation and pulmonary hypertension due to saddle PTE. A thrombus was observed in the bifurcation of the pulmonary artery. The blood flow to the pulmonary artery on the left side was interrupted, and the right side showed severe stenosis. Since the patient was an ELBWI in the acute phase, we decided to use recombinant tissue plasminogen activator (rt-PA) and administered a maintenance dose (0.08 mg/kg/hour), instead of the loading dose. After using rt-PA, the thrombus dissolved in 8 hours without adverse events. This case suggests that starting with a maintenance dose of rt-PA may be an effective treatment option for saddle PTE in ELBWI in the acute phase under the high risk of bleeding.

Evaluation of serum YKL-40 level among clinical risk scores for early mortality in acute pulmonary thromboembolism

INTRODUCTION

Pulmonary embolism (PE) often occurs secondary to deep vein thrombosis and is an important cause of mortality and morbidity. This study aimed to evaluate the relationship between YKL-40 level and clinical risk score in patients with PE.

METHODS

The study included a total of 100 patients, 80 patients diagnosed with PE in the emergency department and 20 healthy controls. Patients with PE were divided into four groups: high-risk patients (n = 20), high-intermediate-risk patients (n = 20), low-intermediate-risk patients (n = 20), and low-risk patients (n = 20). Serum YKL-40 levels were measured by enzyme-linked immunosorbent assay. Pulmonary artery obstruction index (PAOI) was calculated from computed tomography angiography images.

RESULTS

PAOI increased in correlation with PE risk and differed significantly between all patient groups (p < 0.001). Troponin-I levels were significantly higher in the high-risk and high-intermediate-risk groups compared to the other groups (p < 0.001), but did not differ significantly between high-risk and high-intermediate-risk patients (p = 0.09). YKL-40 level was significantly higher in the high-risk PE group than the high-intermediate-risk group (p < 0.001). In receiving operator characteristic curve analysis assessing the discriminatory value of YKL-40 for high-risk PE patients, a cut-off value of 227.2 ng/mL had sensitivity of 85 % and specificity of 70 %.

DISCUSSION

YKL-40 may be an important biomarker in decisions regarding early thrombolytic treatment in patients with high-intermediate-risk PE. In addition, medical treatments targeting YKL-40 may also reduce thrombotic tendency in high-risk patient groups.

Low-dose thrombolysis for submassive pulmonary embolism

The role of thrombolysis in submassive pulmonary embolism (PE) is controversial due to the high risk of hemorrhage. This study aimed to evaluate the role of half-dose tissue-type plasminogen activator (rt-PA) in preventing death/hemodynamic decompensation in submassive (intermediate-risk) PE without increasing the risk of bleeding. In a prospective, non-randomized, open-label, single-center trial, we compared 50 mg rt-PA plus low molecular weight heparin (LMWH) with LMWH in submassive (intermediate-risk) PE. Eligible cases had confirmed pulmonary hypertension on echocardiography, and/or right ventricular cavity expansion and/or interventricular septal deviation on echocardiography, and/or right to left ventricular ratio equal to or greater than 0.9 mm on CT angiography. The primary outcome was death or hemodynamic decompensation within 7 and 30 days after treatment was given. The primary safety outcome was major extracranial bleeding or hemorrhagic stroke within 7 days. Seventy-six patients were included in the study. Total death/hemodynamic decompensation in the first 7 and 30 days was significantly less in the half-dose rt-PA group than in the LMWH group (p=0.028 and p=0.009, respectively). No significant differences were found between the two groups in terms of recurrent embolism and pulmonary hypertension at 6-month follow-up (p=1.000 and p=0.778). There was no intracranial hemorrhage in any of the patients. There were no statistically significant differences between the two groups in terms of major or minor bleeding complications. This trial showed half-dose rt-PA treatment in submassive (intermediate-risk) PE prevented death/hemodynamic decompensation in the first 7-day and 30-day period compared with LMWH treatment without increasing the risk of bleeding.

Assessment of histological characteristics, imaging markers, and rt-PA susceptibility of ex vivo venous thrombi

Venous thromboembolism is a significant source of morbidity and mortality worldwide. Catheter-directed thrombolytics is the primary treatment used to relieve critical obstructions, though its efficacy varies based on the thrombus composition. Non-responsive portions of the specimen often remain in situ, which prohibits mechanistic investigation of lytic resistance or the development of diagnostic indicators for treatment outcomes. In this study, thrombus samples extracted from venous thromboembolism patients were analyzed ex vivo to determine their histological properties, susceptibility to lytic therapy, and imaging characteristics. A wide range of thrombus morphologies were observed, with a dependence on age and etymology of the specimen. Fibrinolytic inhibitors including PAI-1, alpha 2-antiplasmin, and TAFI were present in samples, which may contribute to the response venous thrombi to catheter-directed thrombolytics. Finally, a weak but significant correlation was observed between the response of the sample to lytic drug and its magnetic microstructure assessed with a quantitative MRI sequence. These findings highlight the myriad of changes in venous thrombi that may promote lytic resistance, and imaging metrics that correlate with treatment outcomes.

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.

Efficacy and Safety of Different Dosage of Recombinant Tissue-type Plasminogen Activator (rt-PA) in the Treatment of Acute Pulmonary Embolism: A Systematic Review and Meta-analysis

Reperfusion therapies are recommended for patients with hemodynamic instability or high-risk acute pulmonary embolism (PE). Lower doses of tissue plasminogen activator (rt-PA) could be considered to improve bleeding complications. The aim of this study was to evaluate the efficacy and safety of a reduced dose of rt-PA for the treatment of acute PE, compared with anticoagulation and standard dose. PubMed Central, Scopus, Web of Science and Embase were searched for all relevant randomized studies and prospective observational studies that compared reduced dose of rt-PA with anticoagulation alone or standard dose of rt-PA in patients with acute PE. The risk ratios (RR, with 95% CI) were calculated according to the value of I2. Outcomes were described as bleeding events, all-cause death, and recurrence of PE. Thirteen articles, including four observational studies (4223 patients) and nine RCTs (780 patients), were included. In comparing reduced dose of rt-PA with anticoagulant, a greater incidence of total bleeding events in low dose was showed (RR, 5.08 (95% CI, (1.39–18.6), I2 = 0.0%). In the standard dose rt-PA vs. reduced dose, there was a greater incidence of total bleeding events in the standard dose of rt-PA, RR 1.48 (95% CI, (1.00–2.19), I2 = 0.0%) was shown. There were no statistical differences in recurrent PE or all-cause mortality. It concluded that in the absence of the benefit of a standard dose of rt-PA in comparison with dose reduction, a reduced dose of rt-PA showed a lower rate of total bleeding events and similar efficacy regarding mortality and PE recurrence rate.

Review of Medical Therapies for the Management of Pulmonary Embolism

Traditionally, the management of patients with pulmonary embolism has been accomplished with anticoagulant treatment with parenteral heparins and oral vitamin K antagonists. Although the administration of heparins and oral vitamin K antagonists still plays a role in pulmonary embolism management, the use of these therapies are limited due to other options now available. This is due to their toxicity profile, clearance limitations, and many interactions with other medications and nutrients. The emergence of direct oral anticoagulation therapies has led to more options now being available to manage pulmonary embolism in inpatient and outpatient settings conveniently. These oral therapeutic options have opened up opportunities for safe and effective pulmonary embolism management, as more evidence and research is now available about reversal agents and monitoring parameters. The evolution of the pharmacological management of pulmonary embolism has provided us with better understanding regarding the selection of anticoagulants. There is also a better understanding and employment of anticoagulants in pulmonary embolism in special populations, such as patients with liver failure, renal failure, malignancy, and COVID-19.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Half-Dose Versus Full-Dose Alteplase for Treatment of Pulmonary Embolism

OBJECTIVES

Recent evidence suggests that half-dose thrombolysis for pulmonary embolism may provide similar efficacy with reduced bleeding risk compared with full-dose therapy, but comparative studies are lacking. We aimed to evaluate the effectiveness and safety of half-dose versus full-dose alteplase for treatment of pulmonary embolism.

DESIGN

A retrospective cohort study comparing outcomes in patients receiving half-dose (50 mg) versus full-dose (100 mg) alteplase for pulmonary embolism. We used propensity score matching and sensitivity analyses to address confounding and hospital-level clustering.

SETTING

Data from 420 hospitals obtained from the Premier Healthcare Database between January 2010 and December 2014.

SUBJECTS

Adult critically ill patients with acute pulmonary embolism treated with IV alteplase therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

This study included 3,768 patients: 699 (18.6%) in the half-dose and 3,069 (81.4%) in the full-dose group. At baseline, patients receiving half-dose alteplase required vasopressor therapy (23.3% vs 39.4%; p < 0.01) and invasive ventilation (14.3% vs 28.5%; p < 0.01) less often, compared with full dose. After propensity matching (n = 548 per group), half-dose alteplase was associated with increased treatment escalation (53.8% vs 41.4%; p < 0.01), driven mostly by secondary thrombolysis (25.9% vs 7.3%; p < 0.01) and catheter thrombus fragmentation (14.2% vs 3.8%; p < 0.01). Hospital mortality was similar (13% vs 15%; p = 0.3). There was no difference in cerebral hemorrhage (0.5% vs 0.4%; p = 0.67), gastrointestinal bleeding (1.6% vs 1.6%; p = 0.99), acute blood loss anemia (6.9% vs 4.6%; p = 0.11), use of blood products (p > 0.05 for all), or documented fibrinolytic adverse events (2.6% vs 2.8%; p = 0.82).

CONCLUSIONS

Compared with full-dose alteplase, half-dose was associated with similar mortality and rates of major bleeding. Treatment escalation occurred more often in half-dose-treated patients. These results question whether half-dose alteplase provides similar efficacy with improved safety, and highlights the need for further study before use of half-dose alteplase therapy can be routinely recommended in patients with pulmonary embolism.

Long-term results of low-dose tissue plasminogen activator therapy in acute pulmonary embolism

Recombinant tissue plasminogen activator (rt-PA) is the most commonly used thrombolytic agent in patients with high risk and intermediate to high mortality risk acute pulmonary embolism (PE). Clinical trials have shown early efficacy and safety of low-dose rt-PA. This study investigated the effects of low-dose rt-PA treatment on acute PE in long-term prognosis, recurrence of pulmonary thromboembolism, or the development of late complications. In this study, 48 patients undergoing low-dose rt-PA for the relative contraindications of thrombolytic therapy and 48 patients undergoing standard-dose therapy were evaluated retrospectively. Long-term follow-up investigated the chronic PE, recurrence, and causes of morbidity and mortality.

In both treatment groups, embolism-induced mortality and overall mortality rates were similar in the first 30 days (p=1.000, p=0.714, respectively). Overall mortality rates in long-term follow-up were 41.7% in the low-dose treatment group and 16.7% in the standard-dose treatment group (p=0.013). The mortality rate at the first year was higher in the low-dose-treated group (p=0.011) and most of the deaths were due to accompanying comorbidities. There was no difference in PE recurrence and duration of recurrence between the groups (p=0.598, p=0.073, respectively). Intracranial hemorrhage due to therapy developed in one patient in both groups.

Low-dose thrombolytic therapy in acute PE reduces PE-related mortality in the early period. Long-term follow-up showed that thrombolytic therapy did not affect mortality rates independently of the dose and PE recurrence.

Clinical efficacy of low dose recombinant tissue-type plasminogen activator for the treatment of acute intermediate-risk pulmonary embolism

OBJECTIVES

To investigate the efficacy and safety of initial thrombolysis by recombinant tissue-type plasminogen activator (rt-PA) in compared with anticoagulant therapy in patients with acute intermediate-risk pulmonary embolism (PE).  Methods: Sixty-six patients with acute intermediate-risk PE were randomly assigned to receive rt-PA or LMWH between June 2014 and June 2017 in our department. We obtained information regarding the difference in the right ventricle/left ventricle (RV/LV) ratio, pulmonary artery systolic pressure (PASP), clinical symptoms improvement, PE-related mortality, hemodynamic decompensation, recurrent PE, and major and minor bleeding.  Results: In the rt-PA group, the mean PASP was reduced from 52.0±12.2 at baseline to 34.8±9.4 (p less than 0.001) and the mean RV/LV ratio was reduced from 1.26±0.22 at baseline to 0.96±0.18 (p less than 0.001) at 24 hours. In the LMWH group, the mean PASP was 53.4±12.8 at baseline and 48.5±11.9 at 24 hours (p=0.11), and the mean RV/LV ratio was 1.22±0.19 at baseline and 1.17±0.21 at 24 hours (p=0.31). In comparison with the LMWH group, there was a significant reduction in PASP and an improvement in the symptom severity in the rt-PA group. At 90 days, there was no difference in mortality, recurrent venous thromboembolism and major bleeding as a safety outcome, but increased minor bleeding and decreased hemodynamic decompensation occurred in the rt-PA group. Conclusions: In patients with acute intermediate-risk PE, low dose thrombolytic therapy is considered safe and effective, it can be recommended as an alternative option in clinical treatment.

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.

Comparison of long-term outcomes of 50 and 100 mg rt-PA in the management of acute pulmonary thromboembolism

BACKGROUND

Pulmonary thromboembolism (PTE) is a life-threatening disease. In this study, we aimed to evaluate long-term outcomes of the use of 50 mg recombinant tissue-type plasminogen activator (rt-PA) in the management of PTE in terms of relapse, pulmonary hypertension (PH), mortality and hemorrhage and to compare with the use of 100 mg rt-PA.

METHODS

The study was designed as a retrospective cohort. Patients who were diagnosed as acute PTE and received either 50 or 100 mg rt-PA in a tertiary care hospital between 2010 and 2015 were included in the study. Rates of relapse, PH, mortality (in-hospital and long-term) and hemorrhage (major and minor) were calculated for each treatment group.

RESULTS

A total 117 patients, 73 females and 44 males, were evaluated. Eighty-three patients were administered 100 mg rt-PA, and 34 were administered 50 mg rt-PA. The mean age was lower in the 100 mg group compared to the 50 mg group (61 ± 15 vs 69 ± 14 years). There was a significant decrease in PH in each group at 3 months follow-up (P < .001). Although statistically nonsignificant, the relapse rate was lower in the 50 mg rt-PA group, but the 5-year mortality rate was higher in 50 mg rt-PA group (35.2% vs 27.7%, P = .50). Mortality was associated with older age and presence of malignancy.

CONCLUSIONS

Our results suggest that both doses of rt-PA have similar efficacy. The high mortality rate in the 50 mg group may have resulted from patient selection.

Clinical characteristics, risk factors and outcomes of South-East Asian patients with acute pulmonary embolism

BACKGROUND

The clinical features of acute PE have not been well studied in South-East Asia. We therefore sought to evaluate the clinical characteristics, risk factors and outcomes of patients diagnosed with acute pulmonary embolism (PE) in our region.

METHODS

From January 2008 to March 2013, 343 patients were admitted to our tertiary institution with acute PE. Data were collected retrospectively on baseline clinical characteristics, presenting signs and symptoms, results of electrocardiographic and imaging studies, therapeutic modality and hospital course.

RESULTS

91% of the patients presented with submassive PE. 6.1% of patients had saddle PE. The most common presenting symptom was dyspnea (72.3%) followed by chest pain (12.8%), hemoptysis (2.6%), syncope (2.6%) and cardiovascular collapse (1.2%). Risk factors for PE were idiopathic cause (33.5%), immobilization (21%), malignancy (6.1%) and hypercoagulable state (2.9%). The overall in-hospital mortality was 5%. Factors associated with mortality were massive PE, tachycardia at presentation, right ventricular dysfunction and cardiogenic shock. Bleeding complications occurred in 10.2% of patients (major bleeding in 3.5%).

CONCLUSION

Acute PE in the South-East Asian patients is associated with an overall mortality rate of 5%. The bleeding complications from treatment are also high.

Systemic Thrombolysis for Pulmonary Embolism: Who and How

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