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

Plant-Derived Compounds and Extracts as Modulators of Plasmin Activity-A Review

Functionality of the fibrinolytic system is based on activity of its central enzyme, plasmin, responsible for the removal of fibrin clots. Besides the hemostasis, fibrinolytic proteins are also involved in many other physiological and pathological processes, including immune response, extracellular matrix degradation, cell migration, and tissue remodeling. Both the impaired and enhanced activity of fibrinolytic proteins may result in serious physiological consequences: prothrombotic state or excessive bleeding, respectively. However, current medicine offers very few options for treating fibrinolytic disorders, particularly in the case of plasmin inhibition. Although numerous attempts have been undertaken to identify natural or to develop engineered fibrinolytic system modulators, structural similarities within serine proteases of the hemostatic system and pleiotropic activity of fibrinolytic proteins constitute a serious problem in discovering anti- or profibrinolytic agents that could precisely affect the target molecules and reduce the risk of side effects. Therefore, this review aims to present a current knowledge of various classes of natural inhibitors and stimulators of the fibrinolytic system being well-defined low-molecular plant secondary metabolites or constituents of plant extracts as well as plant peptides. This work also discusses obstacles caused by low specificity of most of natural compounds and, hence, outlines recent trends in studies aimed at finding more efficient modulators of plasmin activity, including investigation of modifications of natural pharmacophore templates.

Association Between the Use of Pre- and Post-thrombolysis Anticoagulation With All-Cause Mortality and Major Bleeding in Patients With Pulmonary Embolism

Objective

To explore the comparative clinical efficacy and safety outcomes of anticoagulation before (pre-) or following (post-) thrombolytic therapy in systemic thrombolytic therapy for pulmonary embolism (PE).

Methods

PubMed, the Cochrane Library, EMBASE, EBSCO, Web of Science, and CINAHL databases were searched from inception through 1 May 2021. All randomized clinical trials comparing systemic thrombolytic therapy vs. anticoagulation alone in patients with PE and those that were written in English were eligible. The primary efficacy and safety outcomes were all-cause mortality and major bleeding, respectively. Odds ratios (OR) estimates and associated 95% confidence intervals (CIs) were calculated. A Bayesian network analysis was performed using R studio software, and then the efficacy and safety rankings were derived.

Results

This network meta-analysis enrolled 15 trials randomizing 2,076 patients. According to the plot rankings, the anticoagulant therapy was the best in terms of major bleeding, and the post-thrombolysis anticoagulation was the best in terms of all-cause mortality. Taking major bleeding and all-cause mortality into consideration, the most safe–effective treatment was the post-thrombolysis anticoagulation in patients who needed thrombolytic therapy. The net clinical benefit analysis comparing associated ICH benefits vs. mortality risks of post-thrombolysis anticoagulation demonstrated a net clinical benefit of 1.74%.

Conclusion

The systemic thrombolysis followed by anticoagulation had a better advantage in all-cause mortality and major bleeding than the systemic thrombolysis before anticoagulation. The adjuvant anticoagulation treatment of systemic thrombolytic therapy should be optimized.

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

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

Regenerative strategies for the consequences of myocardial infarction: Chronological indication and upcoming visions

Heart muscle injury and an elevated troponin level signify myocardial infarction (MI), which may result in defective and uncoordinated segments, reduced cardiac output, and ultimately, death. Physicians apply thrombolytic therapy, coronary artery bypass graft (CABG) surgery, or percutaneous coronary intervention (PCI) to recanalize and restore blood flow to the coronary arteries, albeit they were not convincingly able to solve the heart problems. Thus, researchers aim to introduce novel substitutional therapies for regenerating and functionalizing damaged cardiac tissue based on engineering concepts. Cell-based engineering approaches, utilizing biomaterials, gene, drug, growth factor delivery systems, and tissue engineering are the most leading studies in the field of heart regeneration. Also, understanding the primary cause of MI and thus selecting the most efficient treatment method can be enhanced by preparing microdevices so-called heart-on-a-chip. In this regard, microfluidic approaches can be used as diagnostic platforms or drug screening in cardiac disease treatment. Additionally, bioprinting technique with whole organ 3D printing of human heart with major vessels, cardiomyocytes and endothelial cells can be an ideal goal for cardiac tissue engineering and remarkable achievement in near future. Consequently, this review discusses the different aspects, advancements, and challenges of the mentioned methods with presenting the advantages and disadvantages, chronological indications, and application prospects of various novel therapeutic approaches.

Can VA-ECMO Be Used as an Adequate Treatment in Massive Pulmonary Embolism?

Introduction: Massive acute pulmonary embolism (MAPE) with obstructive cardiogenic shock is associated with a mortality rate of more than 50%. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has been increasingly used in refractory cardiogenic shock with very good results. In MAPE, although it is currently recommended as part of initial resuscitation, it is not yet considered a stand-alone therapy. Material and Methods: All patients with MAPE requiring the establishment of VA-ECMO and admitted to our tertiary intensive care unit were analysed over a period of 10 years. The characteristics of these patients, before, during and after ECMO were extracted and analysed. Results: A total of 36 patients were included in the present retrospective study. Overall survival was 64%. In the majority of cases, the haemodynamic and respiratory status of the patient improved significantly within the first 24 h on ECMO. The 30-day survival significantly increased when ECMO was used as stand-alone therapy (odds ratio (OR) 15.58, 95% confidence interval (CI) 2.65–91.57, p = 0.002). Nevertheless, when ECMO was implanted following the failure of thrombolysis, the bleeding complications were major (17 (100%) vs. 1 (5.3%) patients, p < 0.001) and the 30-day mortality increased significantly (OR 0.11, 95% CI 0.022–0.520, p = 0.006). Conclusions: The present retrospective study is certainly one of the most important in terms of the number of patients with MAPE and shock treated with VA-ECMO. This short-term mechanical circulatory support, used as a stand-alone therapy in MAPE, allows for the optimal stabilisation of patients.

Catheter directed thrombolytic therapy and aspiration thrombectomy in intermediate pulmonary embolism with long term results

BACKGROUND

Catheter directed thrombolysis (CDT) and thrombectomy represent well established techniques for the treatment of intermediate pulmonary embolism (IPE). The long-term effect of catheter directed thrombolysis of IPE is unknown.

METHODS

Clinical, interventional and echocardiographic data from 80 consecutive patients with IPE who were treated with CDT were evaluated. Primary end-points were technical success and major adverse events. Secondary end-points were cardiovascular mortality, all-cause mortality, clinical success, rate of bleeding complications, improvement in pulmonary pressure and echocardiography parameters. CDT completed with alteplase (10 mg bolus and 1 mg/h maintenance dose) through a pig-tail catheter for 24 h. After 24 h, control pulmonary angiography was performed.

RESULTS

In total, 80 patients with a mean age of 59.0 ± 16.8 years were treated. CDT was successful after the first post-operative day in 72 (90%) patients, but thrombus aspiration and fragmentation was performed due to failed thrombolysis in 8 (10%) patients. Final technical and clinical success was reached in 79 (98.8%) and 77 (96.3%) patients, respectively. The mean CDT time in IPE was 27.8 ± 9.6 h. Invasive pulmonary pressure dropped from 57.5 ± 16.7 to 38.9 ± 13.5 (p < 0.001). A caval filter was implanted in 4 (5%) patients. The 1-year major adverse events and cardiovascular mortality rate was 4.0% and 1.4%, respectively. Access site complications (6 major and 6 minor) were encountered in 12 (16.2%) patients.

CONCLUSIONS

Catheter directed thrombolysis in submassive pulmonary embolism had excellent results. However, additional mechanical thrombectomy was necessary in some patients to achieve good clinical outcomes.

Fibrin Matrices as (Injectable) Biomaterials: Formation, Clinical Use, and Molecular Engineering

This review focuses on fibrin, starting from biological mechanisms (its production from fibrinogen and its enzymatic degradation), through its use as a medical device and as a biomaterial, and finally discussing the techniques used to add biological functions and/or improve its mechanical performance through its molecular engineering. Fibrin is a material of biological (human, and even patient's own) origin, injectable, adhesive, and remodellable by cells; further, it is nature's most common choice for an in situ forming, provisional matrix. Its widespread use in the clinic and in research is therefore completely unsurprising. There are, however, areas where its biomedical performance can be improved, namely achieving a better control over mechanical properties (and possibly higher modulus), slowing down degradation or incorporating cell-instructive functions (e.g., controlled delivery of growth factors). The authors here specifically review the efforts made in the last 20 years to achieve these aims via biomimetic reactions or self-assembly, as much via formation of hybrid materials.

Impact of Multidisciplinary Pulmonary Embolism Response Team Availability on Management and Outcomes

Treatment strategies for complex patients with pulmonary embolism (PE) are often debated given patient heterogeneity, multitude of available treatment modalities, and lack of consensus guidelines. Although multidisciplinary Pulmonary Embolism Response Teams (PERT) are emerging to address this lack of consensus, their impact on patient outcomes is not entirely clear. This analysis was conducted to compare outcomes of all patients with PE before and after PERT availability. We analyzed all adult patients admitted with acute PE diagnosed on computed tomography scans in the 18 months before and after the institution of PERT at a large tertiary care hospital. Among 769 consecutive inpatients with PE, PERT era patients had lower rates of major or clinically relevant nonmajor bleeding (17.0% vs 8.3%, p = 0.002), shorter time-to-therapeutic anticoagulation (16.3 hour vs 12.6 hour, p = 0.009) and decreased use of inferior vena cava filters (22.2% vs 16.4%, p = 0.004). There was an increase in the use of thrombolytics/catheter-based strategies, however, this did not achieve statistical significance (p = 0.07). There was a significant decrease in 30-day/inpatient mortality (8.5% vs 4.7%, p = 0.03). These differences in outcomes were more pronounced in intermediate and high-risk patients (mortality 10.0% vs 5.3%, p = 0.02). The availability of multidisciplinary PERT was associated with improved outcomes including 30-day mortality. Patients with higher severity of PE seemed to derive most benefit from PERT availability.

Ultrasound assisted thrombolysis in intermediate-risk patients with pulmonary thromboembolism

Background: Systemic thrombolytic therapy is not recommended for patients with intermediate-risk pulmonary embolism (PE) because of major bleeding and intracranial bleeding overcomes the benefit of reperfusion. Patients and methods: A total of 342 PE patients with intermediate-risk PE from the multicenter Serbian PE registry were involved in the study. Of this group, 227 were not treated with reperfusion therapy (anticoagulation only), 91 were treated with conventional thrombolysis protocols at the discretion of their physicians and 24 patients were treated with ultrasound assisted catheter thrombolysis (USACT) with the EKOS® system. All patients treated with USACT had at least one factor which is associated with an increased risk of bleeding. Other patient characteristics were similar across the treatment groups. All-cause and PE-related mortality at 30 days and rate of major bleeding at 7 days were the main efficacy and safety outcomes of the study. Results: The 30-day all-cause mortality were 11.5% versus 17.6% versus 0.0% for no reperfusion, conventional thrombolysis protocols and USACT groups (p = 0.056), respectively. The difference between the rate of 30-day PE-related mortality was in a favour of EKOS and no reperfusion compare to conventional protocols (0.0% vs. 3.5% vs. 11.0%, p = 0.013, respectively). Major bleeding at 7 days, was presented in 1.8% versus 7.7% versus 8.0% (p = 0.021) in no reperfusion, conventional thrombolysis and USACT groups with no intracranial bleeding. Conclusion: In the patients with intermediate-risk PE and at least one bleeding factor, USACT could be an alternative treatment to anticoagulant therapy only and conventional thrombolytic protocols.

A Narrative Review on Thrombolytics in Advanced CKD: Is it an Evidence-Based Therapy?

PURPOSE

A timely pharmacoinvasive strategy consisting of thrombolytic therapy (TT) plays a pivotal role in three major scenarios: acute ischemic stroke (AIS), acute myocardial infarction (STEMI), and massive pulmonary embolism (PE). Presence of advanced chronic kidney disease (CKD) (estimated glomerular filtration rate < 30 mL/min/1.73 m2), known to disturb thrombotic/thrombolytic equilibrium, causes difficulties for clinicians in evaluating risk-benefit balance, as current guidelines do not address the relationship between TT and the advanced CKD. This narrative review aims to evaluate the most important scientific resources regarding the evidences, benefits, and risks of using thrombolytics in advanced CKD.

METHODS

We searched the electronic database of PubMed for studies evaluating the relationship between renal dysfunction and TT in patients with STEMI, AIS, and massive PE. Randomized controlled trials (RCTs), observational studies including prospective or retrospective cohort studies, reviews, meta-analyses, and guidelines were included if referring to TT for one of the three scenarios in advanced CKD.

RESULTS

Prothrombotic conditions in CKD, associated with an increased risk of hemorrhages, can affect the safety and efficacy of TT. Concerns regarding in-hospital bleeding events and poor clinical outcomes subsequent to TT in advanced CKD continue to cause underutilization or delaying routine reperfusion therapy.

CONCLUSIONS

The impact of TT on the outcomes of advanced CKD patients is poorly understood to date, with scarce data available in current guidelines and conflicting results from observational studies. Until evidence-based data from RCTs will be obtained, the clinical challenge of maximizing benefits for this high-risk subgroup lays in the hands of practicing clinicians.