Potential mechanism of acute stent thrombosis with bivalirudin following percutaneous coronary intervention in acute coronary syndromes

Factors Impacting Stent Thrombosis in Patients With Percutaneous Coronary Intervention and Coronary Stenting: A Systematic Review and Meta-Analysis

Stent thrombosis (ST) is a frequently reported complication in cardiac patients with percutaneous coronary intervention (PCI) that adversely impacts their prognostic outcomes. Medical literature reveals several baseline characteristics of PCI patients that may predict their predisposition to ST and its potential complications. Our systematic review and meta-analysis aimed to determine the diagnostic significance of these baseline parameters in terms of determining the risk of ST among adult patients with PCI. 

We statistically evaluated 18 baseline characteristics of more than 15,500 PCI patients to delineate their stent thrombosis attribution. We included a number of articles focusing on baseline parameters in-stent thrombosis-related PCI scenarios. We explored the articles of interest based on inclusion/exclusion parameters across PubMed, JSTOR, Cochrane library, Google Scholar, and Embase. Medical subject headings (MeSH) words included “stent thrombosis,” “percutaneous coronary intervention,” and “coronary stenting.” We extracted the research articles published between 2005 and 2021 on April 20, 2021. The included studies also focused on procedures and clinical factors concerning their association with PCI-related ST.

Our findings ruled out the progression of abnormal left ventricular ejection fraction (LVEF)-related stent thrombosis in PCI patients (odds ratio {OR}: 9.68, 95% CI: 1.88-49.90, p=0.007). We found an insignificant clinical correlation between stent thrombosis and PCI in the setting of acute coronary syndrome (ACS). Our study outcomes further revealed the absence of stent thrombosis in PCI patients with antiplatelet prescription (OR: 32.42, 95% CI: 21.28-49.39). The findings affirmed the absence of ST in PCI patients receiving aspirin therapy (OR: 32.77, 95% CI: 18.73-57.34; OR: 4.59, 95% CI: 1.97-10.73). The majority of the included studies negated the clinical correlation of stent thrombosis with diabetes mellitus in the setting of PCI (OR: 0.49, 95% CI: 0.06-3.78). Our study did not reveal statistically significant results based on stent thrombosis in PCI patients with drug-eluting stents (OR: 2.91, 95% CI: 0.35-24.49). The findings also did not reveal the impact of cardiac biomarker elevation on stent thrombosis in PCI patients (OR: 8.42, 95% CI: 2.54-27.98, p=0.0005). Eight studies revealed a statistically insignificant correlation between myocardial infarction and stent thrombosis in PCI scenarios (OR: 2.69, 95% CI: 0.89-8.11, p=0.08). The clinical correlation between PCI and stent thrombosis/major bleeding in the setting of hypertension also proved statistically insignificant at 0.67 (OR: 1.31, 95% CI: 0.38-4.51, p=0.97). The study findings did not correlate mean body mass index and multivessel coronary artery disease with ST in PCI scenarios (OR: 1.98, 95% CI: 0.02-239.58, p=0.78; OR: 1.09, 95% CI: 0.58-2.04, p=0.80). Only two studies revealed statistically significant results confirming stent thrombosis in PCI patients with a prior history of PCI (OR: 0.49, 95% CI: 0.23-1.06; OR: 0.33, 95% CI: 0.02-5.59; p=0.03).

Our findings question the clinical significance of baseline characteristics in terms of predicting stent thrombosis in PCI patients. The results support the requirement of future studies to investigate complex interactions between procedural, medicinal, genetic, and patient-related factors contributing to the development of stent thrombosis in PCI patients. 

Self-regulated hirudin delivery for anticoagulant therapy

Pathological coagulation, a disorder of blood clotting regulation, induces a number of cardiovascular diseases. A safe and efficient system for the delivery of anticoagulants to mimic the physiological negative feedback mechanism by responding to the coagulation signal changes holds the promise and potential for anticoagulant therapy. Here, we exploit a "closed-loop" controlled release strategy for the delivery of recombinant hirudin, an anticoagulant agent that uses a self-regulated nanoscale polymeric gel. The cross-linked nanogel network increases the stability and bioavailability of hirudin and reduces its clearance in vivo. Equipped with the clot-targeted ligand, the engineered nanogels promote the accumulation of hirudin in the fibrous clots and adaptively release the encapsulated hirudin upon the thrombin variation during the pathological proceeding of thrombus for potentiating anticoagulant activity and alleviating adverse effects. We show that this formulation efficiently prevents and inhibits the clot formation on the mouse models of pulmonary embolism and thrombosis.

Influence of Direct Thrombin Inhibitor and Low Molecular Weight Heparin on Platelet Function in Patients with Coronary Artery Disease: A Prospective Interventional Trial

INTRODUCTION

The interaction between anticoagulants and platelet function is complex. Previous publications showed mixed results regarding the role of heparins in platelet aggregation. On the other hand, the direct thrombin inhibitor (DTI) dabigatran might enhance the risk of myocardial infarction in patients with atrial fibrillation, which could be related to increased platelet aggregability.

METHODS

This was a prospective, interventional study of patients with chronic coronary artery disease (CAD) taking low-dose aspirin. The objective of the current study was to compare the effects of dabigatran versus enoxaparin on platelet aggregability. Subjects initially were on orally administered dabigatran for 5 days followed by subcutaneously administered enoxaparin after a 30-day washout period. Platelet function was assessed at baseline and after each intervention by multiple electrode aggregometry (MEA-ASPI) (primary endpoint), serum thromboxane B2 (TXB2), VerifyNow Aspirin™, and coagulation tests (secondary endpoints).

RESULTS

Compared to baseline MEA-ASPI values, dabigatran increased platelet aggregation while enoxaparin decreased platelet aggregation (+ 5 U ± 24.1 vs - 6 U ± 22.2, respectively, p = 0.012). The TXB2 assay showed the same pattern (+ 2 pg/ml for dabigatran vs - 13 pg/ml for enoxaparin, p = 0.011). None of the additional tests showed significant differences between the groups. Individually, compared to baseline TXB2 results, enoxaparin significantly decreased platelet activation [33 (16.5-95) pg/mL vs 20 (10-52) pg/mL, respectively, p = 0.026], but no significant differences were observed with dabigatran.

CONCLUSIONS

DTI and anti-Xa drugs exert opposite effects on platelet function. A significant decrease in platelet activation through COX1 (also known as prostaglandin G/H synthase 1) was observed with enoxaparin, but no significant differences in platelet function were observed with dabigatran.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02389582.

A systematic review and meta-analysis of bivalirudin application in peripheral endovascular procedures

OBJECTIVE

The direct thrombin inhibitor bivalirudin (BIV) was shown to be superior to unfractionated heparin (UFH) in percutaneous coronary interventions for reducing procedural blood loss. The aim of this study was to compare outcome profiles of BIV and UFH in peripheral endovascular procedures (PEPs) by synthesizing the currently available data.

METHODS

Following the PRISMA statement, we conducted a comprehensive literature search using Medline, Cochrane CENTRAL, PubMed, EMBASE, CINAHL Google scholar, and clinicaltrials.gov. We recruited randomized, controlled trials and well-conducted observational studies that compared UFH and BIV in PEPs requiring anticoagulation, excluding endovascular cardiac procedures and coronary interventions. Random-effects meta-analyses were conducted to compare the outcome profiles of these two agents.

RESULTS

Thirteen articles containing 14 studies involving a total of 21,057 patients were enrolled. Of these, 2 were randomized controlled trials, 2 were prospective cohort studies, and 10 were retrospective studies. There were no significant differences between BIV and UFH in terms of procedural success rates, major and minor perioperative bleeding, transfusion, perioperative transient ischemic attack, or hemorrhagic strokes. However, compared with UFH, BIV had significantly lower odds ratios (OR) of perioperative mortality (OR, 0.58; 95% confidence interval [CI], 0.40-0.86), major adverse cardiovascular events (OR, 0.65; 95% CI, 0.51-0.83), net adverse clinical events (OR, 0.75; 95% CI, 0.63-0.88), perioperative myocardial infarction (OR, 0.73; 95% CI, 0.55-0.98), major vascular complications (OR, 0.59; 95% CI, 0.39-0.91), and minor vascular complications (OR, 0.58; 95% CI, 0.40-0.84).

CONCLUSIONS

Compared with UFH, PEPs using BIV had comparable procedural success rates and odds of perioperative transient ischemic attack and hemorrhagic stroke. However, procedures with BIV had a lower but nonsignificant odds of perioperative bleeding and transfusion. Depending on the procedures conducted, the patients who received BIV will have reduced or comparable odds of perioperative mortality, myocardial infarction, major adverse cardiovascular events, net adverse clinical events, and major and minor vascular complications. Therefore, BIV may be chosen solely as an alternative procedural anticoagulant to UFH for PEPs.

Design and synthesis of nanoscaled IQCA-TAVV as a delivery system capable of antiplatelet activation, targeting arterial thrombus and releasing IQCA

BACKGROUND

Arterial thrombosis has been associated with a series of pathological conditions, and the discovery of arterial thrombosis inhibitor is of clinical importance.

METHODS

By analyzing the pharmacophores of anti-platelet agents, thrombus targeting peptide and anti-thrombotic nano-systems 3S-1,2,3,4-tetrahydroisoquino-line-3-carbonyl-Thr-Ala-Arg-Gly-Asp(Val)-Val (IQCA-TAVV) was designed and prepared as a nano-scaled arterial thrombosis inhibitor.

RESULTS

In vitro the nanoparticles of IQCA-TAVV were able to adhere onto the surface of activated platelets, attenuate activated platelets to extend pseudopodia and inhibit activated platelets to form aggregators. In vivo IQCA-TAVV targeted arterial thrombus, dose dependently inhibited arterial thrombosis with a 1 nmol/kg of minimal effective dose, and the activity waŝ1670 folds of that of aspirin.

CONCLUSION

IQCA-TAVV represented the design, preparation and application of nanomedicine capable of adhering on the surface of activated platelets, attenuating platelet activation, targeting arterial thrombus and inhibiting arterial thrombosis.

Antithrombotic efficacy of bivalirudin compared to unfractionated heparin during percutaneous coronary intervention for acute coronary syndrome

Bivalirudin is associated with an increased risk of acute stent thrombosis (AST) compared to unfractionated heparin (UFH) in acute coronary syndrome patients (ACS) during short-duration percutaneous coronary intervention (PCI). The mechanisms involved are unknown. We aimed to investigate the antithrombotic efficacy of bivalirudin compared to UFH during PCI. In a monocenter study, we prospectively enrolled 30 patients undergoing PCI for a non-ST elevation ACS. They were randomly assigned to a single intravenous (IV) bolus of UFH (70 IU/kg) or an IV bolus of bivalirudin 0.75 mg/kg followed by a 1.75 mg/kg/h infusion during PCI. All patients received a loading dose (LD) of 180 mg of ticagrelor at the time of PCI. The VASP index and activated partial thromboplastin time (aPTT) were used to assess the course of platelet reactivity (PR) and antithrombotic activity. The two groups were similar regarding baseline, angiographic, and interventional characteristics. There was no difference between the two groups in the course of PR following ticagrelor LD. An optimal PR inhibition was obtained 4 h after the LD of ticagrelor. The level of antithrombotic activity was significantly lower in the bivalirudin group compared to the UFH group (p < 0.001) during PCI but similar at 2 and 4 h post-PCI. We observed that, in ACS undergoing PCI, the antithrombotic efficacy of an IV bolus of bivalirudin is significantly lower than that of a 70-IU/kg UFH bolus. This could contribute to the excess in thrombotic acute events observed during short-duration PCI.

Acute Coronary Stent Thrombosis in Modern Era: Etiology, Treatment, and Prognosis

Acute stent thrombosis (AST) is a rare but life-threatening complication of coronary artery stenting. AST remains a challenging task for cardiologists, despite the application of modern procedural techniques and dual-antiplatelet therapy strategies as well as improved understanding of the underlying pathophysiology. This review focuses on the prevalence, risk factors, prognosis, multiple potential underlying pathogenesis, knowledge gaps, and recommends diagnosis and individualized management strategies of AST.