Targeting thrombin long-term after an acute coronary syndrome: Opportunities and challenges

Sono-responsive smart nanoliposomes for precise and rapid hemostasis application

Massive hemorrhage caused by injuries and surgical procedures is a major challenge in emergency medical scenarios. Conventional means of hemostasis often fail to rapidly and efficiently control bleeding, especially in inaccessible locations. Herein, a type of smart nanoliposome with ultrasonic responsiveness, loaded with thrombin (thrombin@liposome, named TNL) was developed to serve as an efficient and rapid hemostatic agent. Firstly, the hydrophilic cavities of the liposomes were loaded onto the sono-sensitive agent protoporphyrin. Secondly, a singlet oxygen-sensitive chemical bond was connected with the hydrophobic and hydrophilic ends of liposomes in a chemical bond manner. Finally, based on the host guest effect between ultrasound and the sono-sensitizer, singlet oxygen is continuously generated, which breaks the hydrophobic and hydrophilic ends of liposome fragments, causing spatial collapse of the TNL structure, swiftly releases thrombin loaded in the hydrophilic capsule cavity, thereby achieving accurate and rapid local hemostasis (resulted in a reduction of approximately 67% in bleeding in the rat hemorrhage model). More importantly, after thorough assessments of biocompatibility and biodegradability, it has been confirmed that TNL possesses excellent biosafety, providing a new avenue for efficient and precise hemostasis.

Thrombin as target for prevention of recurrent events after acute coronary syndromes

The mechanism underlying thrombus formation in acute coronary syndrome (ACS) involves both platelets and thrombin. While both pathways are targeted in acute care, platelet inhibition has been predominantly administered in the chronic phase, yet thrombin plays a key role in platelet activation and fibrin formation. Among ACS patients, there is also a persistent chronic increase in thrombin generation, which is associated with a higher rate of adverse events. In the setting of post-ACS care with rivaroxaban or vorapaxar, targeting thrombin has been associated with decreased thrombin generation and reduced cardiovascular events, but has been associated with increased bleeding risk. We explored the evidence supporting thrombin generation in the pathophysiology of recurrent events post-ACS and the role of thrombin as a viable therapeutic target. One specific target is factor XI inhibition, which is involved in thrombin generation, but may also allow for the preservation of normal hemostasis.

Prognostic importance of biomarkers associated with haemostatic, vascular and endothelial disturbances in acute coronary syndrome patients in relation to kidney function

BACKGROUND

Patients with kidney failure have a high risk for cardiovascular events. We aimed to evaluate the prognostic importance of selected biomarkers related to haemostasis, endothelial function, and vascular regulation in patients with acute coronary syndrome (ACS), and to study whether this association differed in patients with renal dysfunction.

METHODS

Plasma was collected in 1370 ACS patients included between 2008 and 2015. Biomarkers were analysed using a Proximity Extension Assay and a Multiple Reaction Monitoring mass spectrometry assay. To reduce multiplicity, biomarkers correlating with eGFR were selected a priori among 36 plasma biomarkers reflecting endothelial and vascular function, and haemostasis. Adjusted Cox regression were used to study their association with the composite outcome of myocardial infarction, ischemic stroke, heart failure or death. Interaction with eGFR strata above or below 60 ml/min/1.73 m² was tested.

RESULTS

Tissue factor, proteinase-activated receptor, soluble urokinase plasminogen activator surface receptor (suPAR), thrombomodulin, adrenomedullin, renin, and angiotensinogen correlated inversely with eGFR and were selected for the Cox regression. Mean follow-up was 5.2 years during which 428 events occurred. Adrenomedullin, suPAR, and renin were independently associated with the composite outcome. Adrenomedullin showed interaction with eGFR strata (p = 0.010) and was associated with increased risk (HR 1.88; CI 1.44-2.45) only in patients with eGFR ≥60 ml/min/ 1.73 m².

CONCLUSIONS

Adrenomedullin, suPAR, and renin were associated with the composite outcome in all. Adrenomedullin, involved in endothelial protection, showed a significant interaction with renal function and outcome, and was associated with the composite outcome only in patients with preserved kidney function.

Evaluation of Effectiveness and Tolerability of Fondaparinux in the Management of Symptomatic Acute Coronary Syndrome: A Real-World Evidence-Based Study on an Indian Population

INTRODUCTION

Fondaparinux is a low molecular weight heparin anticoagulant used to manage the full spectrum of acute coronary syndrome (ACS) patients and has proved its efficacy and safety in multiple clinical trials. However, there are limited data available showing whether the same results could be reproduced in real-world practice on an Indian population. Our objective was to determine the effectiveness and tolerability of fondaparinux in the management of symptomatic ACS in real-world clinical practice.

METHODS

The EMR data of hospitalized ACS patients (n = 611), from January 2015 to January 2020, representing UA or NSTEMI or STEMI and were prescribed fondaparinux (2.5 mg once daily) to manage ACS were analyzed. The effectiveness was analyzed as recurrence of ACS and tolerability as total incidence of major bleeding during hospitalization, at 30 days and 180 days. Appropriate statistical analysis was used with a statistically significance of p value < 0.05.

RESULTS

The incidence of recurrent ACS was not seen during hospitalization and in the first 30 days, while in only 0.65% (n = 4) patients, ACS reoccurred within 180 days. In a mean duration of 172.75 ± 3.20 days, UA was reported in 0.49% (n = 3) patients, NSTEMI in 0.16% (n = 1) of patients, and STEMI was not documented. None of the major bleeding events occurred during the entire study period, whereas minor bleeding events were reported during hospitalization 0.98% (n = 6) and at 30 days 0.16% (n = 1). The bleeding events were statistically insignificant (p value > 0.05). No incidences of stent thrombosis were reported during the entire study period.

CONCLUSIONS

In the real world, fondaparinux was found to be effective and tolerable when used to manage symptomatic ACS patients regardless of revascularization procedure with no incidence of stent thrombosis, and minimal recurrent ACS and insignificant increase in bleeding events.

Anticoagulant Therapy for Acute Coronary Syndromes

Anticoagulation in conjunction with antiplatelet therapy is central to the management of acute coronary syndromes (ACS). When used effectively it is associated with a reduction in recurrent ischaemic events including myocardial infarction and stent thrombosis as well as a reduction in death. Effective ischaemic risk reduction whilst balancing bleeding risk remains a clinical challenge. This article reviews the current available evidence for anticoagulation in ACS and recommendations from the European Society of Cardiology.

Novel oral anticoagulants for acute coronary syndrome

Acute coronary syndrome (ACS) is a cardiovascular condition with a multifactorial pathophysiology that includes atherosclerotic plaques, platelet activation and thrombin production, among others. Thrombin production and the prothrombotic state of ACS patients have provided a role for anticoagulants to treat patients during the acute event and has led to subsequent research for the post-acute state. Warfarin has an indication for ACS, however, it is restricted to specific patients and many factors limit its use. Therefore, novel oral anticoagulants (NOACs) are being explored for ACS. Limitations for the use of NOACs in ACS are centered on the increased risk of bleeding that occurs when these agents are added to the current standard of care with dual antiplatelet therapy. Rivaroxaban is the only NOAC that has achieved approval in Europe for this indication with none of the NOAC currently approved in the US for use in ACS. Ongoing studies for rivaroxaban and apixaban may provide evidence to further clarify the place in therapy for NOAC agents in ACS management.