Double-blind study of the safety of clopidogrel with and without a loading dose in combination with aspirin compared with ticlopidine in combination with aspirin after coronary stenting : the clopidogrel aspirin stent international cooperative study (CLASSICS)

Peri-operative anti-inflammatory drug use and seizure recurrence after resective epilepsy surgery: Target trials emulation

We conducted a retrospective observational study to examine whether anti-inflammatory medications prescribed peri-operatively of resective brain surgery can reduce long-term seizure recurrence for individuals with drug-resistant focal epilepsy. We used insurance-claims data from across the United States to screen medications prescribed to 1,993 individuals undergoing epilepsy. We then validated the results in a well-characterized cohort of 671 epilepsy patients from a major surgical center. Twelve medications met the screening criteria and were evaluated, identifying dexamethasone and zonisamide as potentially beneficial. Dexamethasone reduced seizure recurrence by 42% over 9 years of follow-up (hazard-ratio = 0.742; 95% CI = 0.662, 0.831), and zonisamide reduced recurrence by 33% (HR = 0.782; 95% CI = 0.667, 0.917). While dexamethasone could not be validated, analysis of zonisamide in the clinical cohort corroborated the beneficial effect (HR = 0.828; 95% CI = 0.706, 0.971). If prospectively validated, this study suggests surgeons could improve long-term outcomes of epilepsy surgery by medically reducing neuro-inflammation in the surgical bed.

The pharmacology of antiplatelet agents for primary, secondary, and tertiary prevention of ischemic stroke

INTRODUCTION

Ischemic etiology accounts for two thirds of all strokes in which platelet activation and aggregation play a major role. A variety of antiplatelet therapies have been tested for primary, secondary, and tertiary prevention, with certain patient subtypes benefiting more than others from a specific regimen.

AREAS COVERED

This review aims at synthetizing current evidence on pharmacology of antiplatelet agents approved for primary, secondary, and tertiary stroke prevention and their application among possible patient subtypes that may benefit more from their administration.

EXPERT OPINION

Management of ischemic stroke has largely evolved over the past decades. A better understanding of stroke pathophysiology has allowed to identify patients who can benefit most from antiplatelet therapies, with varying degrees of benefit depending on whether these agents are being used for primary, secondary, or tertiary prevention. Importantly, the antiplatelet treatment regimens currently available have expanded and no longer limited to aspirin but include other drugs such as P2Y12 and phosphodiesterase inhibitors, also used in combination, as well as precision medicine approaches using genetic testing aiming at optimizing the safety and efficacy in this population.

Clopidogrel resistance and its relevance: Current concepts

Clopidogrel is the most widely used P2Y12 receptor inhibitor (P2Y12i) as a part of dual antiplatelet therapy along with aspirin. Clopidogrel is a pro-drug and is metabolized to its active metabolite by the hepatic enzyme cytochrome P4502C19 (CYP2C19). This active metabolite is responsible for the antiplatelet action of clopidogrel. Recent studies have demonstrated that single nucleotide polymorphisms in the CYP2C19 gene, including CYP2C19*2,*3,*4, and *5 alleles, result in reduced production of the active metabolite of clopidogrel, and hence reduced inhibition of platelet aggregation. This in turn enhances the incidence of stent thrombosis and recurrent cardiovascular (CV) events. We report a case of coronary stent thrombosis due to clopidogrel resistance proven by CYP2C19 genotyping. We then review the literature on clopidogrel resistance and its impact on CV outcomes. Subsequently, we discuss the methods of diagnosis of resistance, evidence from clinical trials for tailoring clopidogrel therapy, the role of potent P2Y12 inhibitors, the current guidelines, and future directions.

Consideration of the Medical Economics of Cardiac Genetics, Focusing on the Cost-Effectiveness of P2Y12 Inhibitor Selection Based on the CYP2C19 Loss-of-Function Allele: A Semi-Systematic Review

Medical economics is essential in cardiac genetics for the clinical application and development of research results. However, related economic evaluations are unclear, and limited systematic reviews are available on the cost-effectiveness of drug selection based on the CYP2C19 LOF allele. This review analyzed research in the MEDLINE database from January 2012 to June 2023 using more evidence than a well-designed cohort study, owing to the lack of relevant research in the database. For example, cost-effectiveness analyses are often reported as simulation assays, and were included in this analysis. No conditions related to patient background or antiplatelet drug therapy were selected. This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement (2020). Twenty-one cardiac genetic studies were selected, of which nineteen involved antiplatelet therapy after PCI. A universal group consisting of clopidogrel and other drugs was used as the baseline and compared with the drug selection groups based on the CYP2C19 LOF allele. The incremental cost–effectiveness ratio was generally below 50,000 (US$/Qaly), and drug selection based on the CYP2C19 LOF allele was the most cost-effective, followed by universal clopidogrel. Although cardiac genetic and economic data are rudimentary, this review indicates that antiplatelet therapy (drug selection based on the CYP2C19 LOF allele) after PCI is generally cost-effective.

Shortened Duration of Dual Antiplatelet Therapy Following Percutaneous Coronary Intervention: A Contemporary Clinical Review

Percutaneous coronary intervention with stent implantation is an integral aspect of minimally interventional cardiac procedures. The technology and techniques behind stent design and implantation have evolved rapidly over several decades. However, continued discourse remains around optimal peri- and post-interventional management with dual antiplatelet therapy to minimise both major cardiovascular or cerebrovascular events and iatrogenic bleeding risk. Standard guidelines around dual antiplatelet therapy historically recommended long-term dual antiplatelet therapy for 12 months (with consideration for >12 months in certain patients); however, emerging data and generational improvements in the safety of drug-eluting stents have ushered in a new era of short-term therapy to reduce the incidence of major bleeding events. This case review will provide an overview of the current state of guidelines around duration of dual antiplatelet therapy and examine recent updates and continued gaps in existing research.

Comparison of In-Hospital Major Adverse Cardiovascular Events in Patients with Acute Myocardial Infarction Treated with Ticagrelor or Clopidogrel in the Emergency Department: A Propensity Score Matched Retrospective Cohort Study

BACKGROUND

Dual antiplatelet therapy (DAPT) is a standard treatment option for acute myocardial infarction (AMI). The difference between the efficacy of ticagrelor and clopidogrel in the emergency department (ED) before percutaneous coronary intervention (PCI) remains unknown. The present study compared the in-hospital major adverse cardiovascular event (MACE) rates between patients with AMI treated with clopidogrel and those treated with ticagrelor in the ED before PCI.

METHODS

We retrospectively collected the data of patients diagnosed as having AMI in the ED. Patients were only included if they had successfully received complete DAPT with aspirin and ticagrelor/clopidogrel in the ED and had undergone PCI. The patients were divided into two groups according to their DAPT regimen. The primary outcome was the rate of in-hospital MACEs. The secondary outcomes included an unexpected return to the ED within 72 h, readmission within 14 d, and revascularization.

RESULTS

A total of 1836 patients were enrolled. Patients in the ticagrelor group had a lower in-hospital MACE rate (3.01% versus 7.51%, p < 0.001) and in-hospital mortality rate (2.15% versus 5.70%, p < 0.001) than those in the clopidogrel group. Multivariate logistic regression analysis revealed ticagrelor was independently associated with a lower risk of in-hospital MACEs (odds ratio [OR]: 0.53, 95% CI: 0.32-0.88, p = 0.013). After propensity score matching, the risk of in-hospital MACEs remained significantly lower in the ticagrelor group (OR 0.42, 95% CI: 0.21-0.85, p = 0.016).

CONCLUSION

DAPT with ticagrelor and aspirin in the ED before PCI is associated with a lower in-hospital MACE rate among patients with AMI.

Novel Aspects Targeting Platelets in Atherosclerotic Cardiovascular Disease—A Translational Perspective

Platelets are important cellular targets in cardiovascular disease. Based on insights from basic science, translational approaches and clinical studies, a distinguished anti-platelet drug treatment regimen for cardiovascular patients could be established. Furthermore, platelets are increasingly considered as cells mediating effects “beyond thrombosis”, including vascular inflammation, tissue remodeling and healing of vascular and tissue lesions. This review has its focus on the functions and interactions of platelets with potential translational and clinical relevance. The role of platelets for the development of atherosclerosis and therapeutic modalities for primary and secondary prevention of atherosclerotic disease are addressed. Furthermore, novel therapeutic options for inhibiting platelet function and the use of platelets in regenerative medicine are considered.

Periprocedural P2Y12 inhibitors improve perioperative outcomes after carotid stenting by primarily decreasing strokes

OBJECTIVE

The continuation of antiplatelet agents in the periprocedural period around carotid stenting (CAS) procedures is felt to be mandatory to minimize the risk of periprocedural stroke. However, the optimal antiplatelet regimen is unclear, with some advocating dual antiplatelet therapy, and others supporting the use of P2Y₁₂ inhibitors alone. The objective of this study was to evaluate the periprocedural effect of P2Y₁₂ inhibitors for CAS.

METHODS

The Vascular Quality Initiative was used from years 2007 to 2020. All transcarotid artery revascularization (TCAR) and transfemoral carotid artery stenting (TF-CAS) procedures were included. Patients were stratified based on perioperative use of P2Y₁₂ inhibitors as well as symptomatic status. Primary end points were perioperative neurological events (strokes and transient ischemic attacks). Secondary end points were mortality and myocardial infarction.

RESULTS

A total of 31,036 CAS procedures were included for analysis, with 49.8% TCAR and 50.2% TF-CAS cases; 63.8% of patients were male and 82.3% of patients were on a P2Y₁₂ inhibitor. P2Y₁₂ inhibitor use was more common in males, asymptomatic patients, those older than 70 years, and concurrent statin use. P2Y₁₂ inhibitors were more likely to be used in TCAR cases than in TF-CAS cases (87.3% vs 76.8%; P < .001). The rate of periprocedural neurological events in the whole cohort was 2.6%. Patients on P2Y₁₂ inhibitors were significantly less likely to experience a periprocedural neurological event (2.3% vs 3.9%; P < .001) and mortality (0.6% vs 2.1%; P < .001) than those who were not on a P2Y₁₂ inhibitor. There was no effect on the rates of myocardial infarction. On multivariate analysis, both symptomatic and asymptomatic patients on P2Y₁₂ inhibitors were significantly less likely to develop perioperative neurological events. Additionally, the use of P2Y₁₂ inhibitors demonstrated an independent significant effect in reducing of the rate of perioperative stroke (odds ratio, 0.29; 95% confidence interval, 0.25-0.33). Finally, additional analysis of the types of P2Y₁₂ inhibitors used revealed that all seemed to be equally effective in decreasing the periprocedural neurological event rate.

CONCLUSIONS

The use of perioperative P2Y₁₂ inhibitors seems to markedly decrease the perioperative neurological event rate with TCAR and TF-CAS in both symptomatic and asymptomatic patients and should be strongly considered. Patients with contraindications to P2Y₁₂ inhibitors may not be appropriate candidates for any CAS procedure. Additionally, alternative types of P2Y₁₂ inhibitors seem to be equally effective as clopidogrel. Finally, an analysis of the Vascular Quality Initiative demonstrates that, even for TCAR cases, only 87.3% of patients seem to be on P2Y₁₂ inhibitors in the periprocedural period, leaving room for significant improvement.

Clopidogrel Resistance and Ticagrelor Replacement in Dual Antiplatelet Therapy for Carotid Artery Stenting

BACKGROUNDS

Resistance to the pharmacological effect of clopidogrel in patients undergoing dual antiplatelet therapy for carotid stenting may increase the risk of periprocedural neurological events. The purpose of the study was to describe the phenomenon of clopidogrel resistance in a series of patients undergoing carotid stenting.

METHODS

Data of patients who consecutively underwent carotid stenting from November 2016 to December 2020 for a significant stenosis and who underwent a dual antiplatelet therapy using acetyl-salicylic acid and clopidogrel were prospectively collected. Patients who were already taking a different thienopyridine were excluded. The effectiveness of antiplatelet drugs was assessed by the impedance aggregometry test. Primary endpoint was to evaluate the incidence of clopidogrel resistance and the effectiveness of ticagrelor as alternative therapy. P values < 0.05 were considered statistically significant.

RESULTS

Two-hundred patients (80 females, 40%) underwent stenting for carotid stenosis (94% asymptomatic). The phenomenon of clopidogrel resistance was observed in 38 patients (19%), in whom clopidogrel was replaced by ticagrelor (90 mg/bis in die) with 100% effectiveness at aggregometry test. Platelet counts was associated to clopidogrel resistance (P = 0.001). There was no stent thrombosis at 30 days, neither major hemorrhagic events; a total of 12/200 major adverse cardiovascular events occurred (6%), including 1 in the group of patients who took ticagrelor and 11 in group of patients under clopidogrel (2.6% versus 6.7%, P = 0.55).

CONCLUSIONS

Clopidogrel was ineffective in 19% of patients undergoing carotid stenting. Platelet count seemed to affect this phenomenon. In these patients, clopidogrel was effectively replaced by ticagrelor.

High-on-treatment platelet reactivity predicts adverse outcome after carotid artery stenting: A prospective study

BACKGROUND AND PURPOSE

High-on-treatment platelet reactivity (HTPR) has been established as a predictor of major adverse cardiovascular events (MACE) in patients undergoing percutaneous coronary interventions on dual antiplatelet therapy (DAPT), but no data are available on its predictive value in patients on DAPT after carotid artery stenting (CAS). We aimed to evaluate the possible association between HTPR in patients on aspirin plus clopidogrel therapy after CAS and subsequent MACE.

METHODS

All consecutive patients treated with CAS in a single institution were enrolled in a prospective clinical study. HTPR was evaluated with 5 different laboratory assays carried out just before CAS. MACE incidence (cerebral ischemia, myocardial infarction, stent thrombosis, acute limb ischemia and vascular death) was evaluated at 30 days and thereafter at yearly visits.

RESULTS

A total of 300 patients were enrolled in the study, and eight were then excluded because blood samples resulted unsuitable for the laboratory testing or CAS aborted for technical problems. Median follow-up was 5.8 years and during this period 47 MACE occurred. HTPR detected by multiplate electronic aggregometry (MEA) and the VASP phosphorylation assay (VASP) were associated with a significantly enhanced risk of MACE (p = 0.048 and p = 0.038, respectively). However, HTPR to three tests (HTPR3) was more strongly predictive of increased risk of a vascular event at follow up (p = 0.005) at bivariate analysis and also at Cox regression multivariate analysis (p = 0.002).

CONCLUSIONS

HTPR to three different assays (mainly to VASP + PFA P2Y+ VerifyNow) in patients on DAPT after CAS has predictive value for subsequent MACE. Prospective studies to assess whether platelet function testing-guided antiplatelet therapy is superior to standard DAPT in patient undergoing CAS should be considered.

An Uncommon Case of Acute Coronary Stent Thrombosis

Coronary stent thrombosis is an uncommon complication of percutaneous coronary intervention, which can result in myocardial infarction and often death. We present a case of acute stent thrombosis in a patient with newly diagnosed triple vessel coronary artery disease occurring within less than an hour of stent placement along with a review of the literature.

Guided vs. conventional anti-platelet therapy for patients with acute coronary syndrome: A meta-analysis of randomized controlled trials

Background

Whether guided antiplatelet therapy in patients with acute coronary syndrome (ACS) is effective in improving net clinical benefits compared with conventional antiplatelet therapy remains controversial. Therefore, we assessed the safety and efficacy of guided antiplatelet therapy in patients with ACS and undergoing percutaneous coronary intervention.

Method

We searched PubMed, EMBASE, and Cochrane Library databases to select the relevant randomized controlled trials comparing the guided and conventional antiplatelet therapy in patients with ACS. The primary and safety outcomes are major adverse cardiovascular events (MACE) and major bleeding, respectively. The efficacy outcomes included myocardial infarction, stent thrombosis, all-cause death, and cardiovascular death. We selected the relative risk (RR) and 95% confidence intervals (CIs) as effect size and calculated it using the Review Manager software. In addition, we evaluated the final results by trial sequential analysis (registered by PROSPERO, CRD 42020210912).

Results

We selected seven randomized controlled trials and included 8,451 patients in this meta-analysis. Guided antiplatelet therapy can significantly reduce the risk of MACE (RR 0.64, 95% CI 0.54-0.76, P < 0.00001), myocardial infarction (RR 0.62, 95% CI 0.49-0.79, P = 0.0001), all-cause death (RR 0.61, 95% CI 0.44-0.85, P = 0.003), and cardiovascular death (RR 0.66, 0.49-0.90, P = 0.009). In addition, there is no significant difference between the two groups in stent thrombosis (RR 0.67, 95% CI 0.44-1.03, P = 0.07) and major bleeding (RR 0.86, 95% CI 0.65-1.13, P = 0.27). The subgroup analysis showed that the guided group based on genotype tests could bring benefits in MACE and myocardial infarction.

Conclusions

The guided antiplatelet therapy is not only associated with a comparable risk of bleeding but also with a lower risk of MACE, myocardial infarction, all-cause death, cardiovascular death, and stent thrombosis than the conventional strategy in patients with ACS.

The Evolution of Antiplatelet Therapy After Percutaneous Coronary Interventions: A 40-Year Journey

Antiplatelet therapy has a critical role to play in the successful management of patients undergoing percutaneous coronary intervention (PCI). Over the past 40 years, a multitude of participants worldwide have been enrolled in trials evaluating the impact of antiplatelet agents on clinical outcomes. The use of aspirin in unstable angina in the Canadian Aspirin trial was key to establishing the benefit of aspirin in acute coronary syndrome. The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) trial demonstrated that the P2Y12 inhibitor clopidogrel, when added to aspirin, reduced major cardiovascular events. While the use of antiplatelet agents in coronary artery disease antedates the introduction of PCI and remains the cornerstone of secondary prevention of atherosclerotic cardiovascular disease, strategies aiming to optimise their best use are still constantly evolving. In this review, the major randomised trials shaping current clinical practice for the use of aspirin and P2Y12 inhibitors in patients undergoing PCI are summarised, with a focus on aspirin-free strategies and on the role of P2Y12 inhibitor treatment before PCI, two major topics of ongoing investigation that are critical to patient care but that are not addressed in current practice guidelines. Multiple questions remain regarding the use of antiplatelet agents after PCI, including the personalisation of dosing, intensity, pharmacologic formulation, and duration of antiplatelet therapy based on individual patient characteristics and the optimal treatment of patients at high bleeding risk.

Elevated serum C1q is an independent predictor of high residual platelet reactivity in CAD patients receiving clopidogrel therapy

Background

Inflammation increases the risk of thrombosis in coronary artery disease (CAD) patients and affects the antiplatelet efficacy of clopidogrel. C1q interacts with platelets to activate platelets and induce thrombosis by participating in and regulating the inflammatory response. Whether C1q affects adenosine diphosphate (ADP)-induced platelet reactivity during clopidogrel therapy was unclear and our study aimed to explore the issue.

Method

We enrolled 1,334 CAD patients receiving clopidogrel therapy and evaluated the association between C1q level and high residual platelet reactivity (HRPR) using logistic regression and restricted cubic spline (RCS). HRPR was defined as ADP-induced maximum amplitude (MA_ADP) > 47 mm plus ADP-induced platelet aggregation (ADP_i) < 50%.

Results

A total of 516 patients (38.7%) performed HRPR. The frequency of HRPR increases with the increase in C1q level (26.3%, 38.4%, 43.2%, and 46.7% for the 1st to 4th quartile of C1q). The result of multivariate logistic regression demonstrated elevated C1q as an independent predictor for HRPR (2^nd quartile: OR = 1.722, 95% CI 1.215–2.440; 3^rd quartile: OR = 2.015, 95% CI 1.413–2.874; 4^th quartile: OR = 2.362, 95% CI 1.631–3.421, compared to the 1st quartile). RCS depicted the nonlinear relationship between C1q and HRPR risk (p for non-linear < 0.05).

Conclusion

The current research is the first to explore the association of C1q and ADP-induced platelet reactivity and to demonstrate elevated C1q as an independent risk factor for HRPR in CAD patients during clopidogrel therapy.

Current and Future Insights for Optimizing Antithrombotic Therapy to Reduce the Burden of Cardiovascular Ischemic Events in Patients with Acute Coronary Syndrome

The pharmacological treatment strategies for acute coronary syndrome (ACS) in recent years are constantly evolving to develop more potent antithrombotic agents, as reflected by the introduction of more novel P2Y₁₂ receptor inhibitors and anticoagulants to reduce the ischemic risk among ACS patients. Despite the substantial improvements in the current antithrombotic regimen, a noticeable number of ACS patients continue to experience ischemic events. Providing effective ischemic risk reduction while balancing bleeding risk remains a clinical challenge. This updated review discusses the currently approved and widely used antithrombotic agents and explores newer antithrombotic treatment strategies under development for the initial phase of ACS.

Antiplatelet therapy after percutaneous coronary intervention

Antiplatelet therapy is key to reducing local thrombotic complications and systemic ischaemic events among patients undergoing percutaneous coronary interventions (PCI), but it is inevitably associated with increased bleeding. The continuous refinement in stent technologies, together with the high incidence of ischaemic recurrences after PCI and the understanding of prognostic implications associated with bleeding, have led to a substantial evolution in antiplatelet treatment regimens over the past decades. Numerous investigations have been conducted to better stratify patients undergoing PCI according to their ischaemic and bleeding risks and to implement antithrombotic regimens accordingly. Evidence from these investigations have resulted in a number of antithrombotic treatment options as recommended by recent guidelines. In this State-of-the-Art review we provide the rationale, summarise the evidence, and discuss current and future directions of antiplatelet treatment regimens after PCI.

Antiplatelet Therapy in Patients Undergoing Elective Percutaneous Coronary Intervention

PURPOSE OF REVIEW

The evidence for use of dual antiplatelet therapy (DAPT) for patients undergoing percutaneous coronary intervention (PCI) in the elective setting is relatively sparse and is based on data from more than two decades ago. We will review the evidence supporting the use of DAPT with focus on stable patients undergoing elective PCI, including the role of potent P₂Y₁₂ inhibitors, modified DAPT durations, and more recently, aspirin discontinuation.

RECENT FINDINGS

Clopidogrel is the recommended P₂Y₁₂ inhibitor in the elective PCI setting. The benefit of more potent P₂Y₁₂ inhibitors such as ticagrelor or prasugrel in stable patients is unproven, but their use might be reasonable in those with high clinical or angiographic features of increased ischemic risk without increased risk of bleeding. Moreover, extending DAPT beyond 12 months is associated with a reduction in ischemic events but also increased bleeding. In contrast, shortening DAPT (3-6 months) reduces bleeding compared with 1 year of treatment, but it is also probably associated with increased ischemic events, mainly in higher-risk patients undergoing complex PCI. Recently, early aspirin discontinuation at 3 months (and perhaps as early as 1 month) following PCI reduces bleeding, with no evidence to suggest an increase in ischemic events. Clopidogrel is the P₂Y₁₂ inhibitor of choice, while more data are required to support the use of more potent P₂Y₁₂ inhibitors in stable patients. The duration of DAPT should be tailored to individual patient ischemic and bleeding risks. New strategies, such as early aspirin discontinuation, are promising to reduce bleeding risk without increase in ischemic risk.

2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The guideline for coronary artery revascularization replaces the 2011 coronary artery bypass graft surgery and the 2011 and 2015 percutaneous coronary intervention guidelines, providing a patient-centric approach to guide clinicians in the treatment of patients with significant coronary artery disease undergoing coronary revascularization as well as the supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from May 2019 to September 2019, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, CINHL Complete, and other relevant databases. Additional relevant studies, published through May 2021, were also considered.

STRUCTURE

Coronary artery disease remains a leading cause of morbidity and mortality globally. Coronary revascularization is an important therapeutic option when managing patients with coronary artery disease. The 2021 coronary artery revascularization guideline provides recommendations based on contemporary evidence for the treatment of these patients. The recommendations present an evidence-based approach to managing patients with coronary artery disease who are being considered for coronary revascularization, with the intent to improve quality of care and align with patients' interests.

Antiplatelet Therapy After Percutaneous Coronary Intervention - Past, Current and Future Perspectives

Optimal antiplatelet therapy after percutaneous coronary intervention (PCI) has been changed in parallel with the improvements of coronary stent and antiplatelet therapy. Over the past 25 years, dual antiplatelet therapy (DAPT) with aspirin plus P2Y₁₂inhibitor has been the standard of care used after coronary stent implantation. First-generation drug-eluting stent (DES) appeared to increase the risk of late stent thrombosis, and duration of DAPT was prolonged to 12 months. DAPT duration up to 12 months was the dominant strategy after DES implantation in the subsequent >10 years, although there was no dedicated randomized controlled trial supporting this recommendation. The current recommendation of DAPT duration is getting shorter due to the development of new-generation DES, use of a P2Y₁₂inhibitor as a monotherapy, and the increasing prevalence of high-bleeding risk patients. Furthermore, an aspirin-free strategy is now emerging as one of the novel strategies of antiplatelet therapy after PCI. This review gives an overview of the history of antiplatelet therapy and provides current and future perspectives on antiplatelet therapy after PCI.

Genetic testing in patients undergoing percutaneous coronary intervention: rationale, evidence and practical recommendations

INTRODUCTION

Clopidogrel is the most frequently utilized P2Y12 inhibitor and is characterized by broad interindividual response variability resulting in impaired platelet inhibition and increased risk of thrombotic complications in a considerable number of patients. The potent P2Y12 inhibitors, prasugrel and ticagrelor, can overcome this limitation but at the expense of an increased risk of bleeding. Genetic variations of the cytochrome P450 (CYP) 2 C19 enzyme, a key determinant in clopidogrel metabolism, have been strongly associated with clopidogrel response profiles prompting investigations of genetic-guided selection of antiplatelet therapy.

AREAS COVERED

The present manuscript focuses on the rationale for the use of genetic testing to guide the selection of platelet P2Y12 inhibitors among patients undergoing percutaneous coronary intervention (PCI). Moreover, a comprehensive appraisal of the available evidence and practical recommendations is provided.

EXPERT COMMENTARY

Implementation of genetic testing as a strategy to guide the selection of therapy can result in escalation (i.e. switching to prasugrel or ticagrelor) or de-escalation (i.e. switching to clopidogrel) of P2Y12 inhibiting therapy. Most recent investigations support the clinical benefit of a genetic guided selection of antiplatelet therapy in patients undergo PCI. Integrating the results of genetic testing with clinical and procedural variables represents a promising strategy for a precision medicine approach for the selection of antiplatelet therapy among patients undergoing PCI.

Evolution of antithrombotic therapy in patients undergoing percutaneous coronary intervention: a 40-year journey

Since its introduction in 1977, percutaneous coronary intervention has become one of the most commonly performed therapeutic procedures worldwide. Such widespread diffusion, however, would have not been possible without a concomitant evolution of the pharmacotherapies associated with this intervention. Antithrombotic agents are fundamental throughout the management of patients undergoing coronary stent implantation, starting from the procedure itself to the long-term prevention of cardiovascular events. The last 40 years of interventional cardiology have seen remarkable improvements in both drug therapies and device technologies, which largely reflected a progressive understanding of the pathophysiological mechanisms of coronary artery disease, as well as procedure- and device-related adverse events. The purpose of this article is to provide an overview of the important milestones in antithrombotic pharmacology that have shaped clinical practice of today while also providing insights into knowledge gaps and future directions.

Associations of PER3 polymorphisms with clopidogrel resistance among Chinese Han people treated with clopidogrel

Background

Changes in circadian rhythm are related to various diseases, such as immune system diseases and cardiovascular diseases. The PERIOD3 (PER3) clock gene is one of the most important genes in the rhythm regulation system. Our goal was to evaluate the possible association between the PER3 rs228729 (T/C) polymorphism or PER3 rs2797685(T/C) polymorphism and clopidogrel resistance (CR) and to study the impact of clinical baseline data on clopidogrel resistance.

Methods

PER3 polymorphisms rs2797685 (T/C) and rs228729 (T/C) were assessed in 156 patients with (72) and without (84) CR. Blood samples were collected and analyzed after the application of clopidogrel for interventional therapy.

Results

Age, albumin, PLT, and PCT levels influenced the risk of CR (p < 0.05). For rs2797685, when the PCT value was greater than 0.19, patients with the TT + TC genotype had an increased risk of clopidogrel resistance compared with those with the CC genotype (PCT ≥ 0.19, p = 0.014; PCT p = 0.004). In patients with albumin values greater than 40 or PCT greater than 0.19, those with the rs228729 TT + TC genotype had an increased risk of clopidogrel resistance compared with those with the CC genotype (albumin≥40, TT+TC:CC, p = 0.01, albumin p = 0.005; PCT ≥ 0.19, TT+TC:CC, p < 0.001, PCT p = 0.004). Logistic regression analysis of clinical baseline data and genotype showed that high albumin is a protective factor against clopidogrel resistance. The PER3 gene polymorphism has no clear correlation with clopidogrel resistance.

Conclusion

In summary, our research shows that PER3 SNPs may be helpful to assess the pathogenesis of CR.

Efficacy of aspirin, clopidogrel, and ticlopidine in stroke prevention: A population-based case-cohort study in Taiwan

Background

In real-world practice settings, there is insufficient evidence on the efficacy of antiplatelet drugs, including clopidogrel, aspirin, and ticlopidine, in stroke prevention.

Purpose

To compare the efficacies between aspirin and clopidogrel and aspirin and ticlopidine in stroke prevention.

Methods

This population-based case-cohort study utilized the data obtained from a randomized sample of one million subjects in the Taiwan National Health Insurance Research Database. Patients who were hospitalized owing to the primary diagnosis of ischemic stroke from January 1, 2000 to December 31, 2010 and treated with aspirin, ticlopidine, or clopidogrel were included in the study. Propensity score matching with a 1:4 ratio was performed to compare aspirin with ticlopidine and clopidogrel. The criteria for inclusion were the use of one of the three antiplatelet drugs for more than 14 days within the first month after the stroke and then continued use of the antiplatelet drugs until the study endpoint of recurrent stroke.

Results

During the 3-year follow-up period, the recurrent stroke rates were 1.62% (42/2585), 1.48% (3/203), and 2.55% (8/314) in the aspirin, ticlopidine, and clopidogrel groups, respectively. Compared with the patients treated with aspirin, those treated with clopidogrel and ticlopidine showed competing risk-adjusted hazard ratios of recurrent stroke of 2.27 (1.02–5.07) and 0.62 (0.08–4.86), respectively.

Conclusion

Compared with the patients treated with aspirin, those treated with clopidogrel were at a higher risk of recurrent stroke. For stroke prevention, aspirin was superior to clopidogrel whereas ticlopidine was not inferior to aspirin.

Safety and efficacy of P2Y12 inhibitor monotherapy in patients undergoing percutaneous coronary interventions

Introduction: Antiplatelet therapy represents a key strategy for the prevention of thrombotic complications in patients with both acute and chronic coronary syndromes, particularly those undergoing percutaneous coronary intervention (PCI). Nevertheless, dual antiplatelet therapy (DAPT) is associated with a bleeding risk proportionate to its duration. Ever growing appreciation of the prognostic implications associated with bleeding and the development of safer stent platforms over the past years have led to a number of novel antiplatelet treatment strategies being tested among patients undergoing PCI. Areas covered: P2Y₁₂ inhibitor monotherapy after ashort course DAPT has emerged as ableeding reduction strategy to mitigate such risk while still preventing thrombotic complications. In this review we describe the latest evidence regarding the safety and efficacy of P2Y₁₂ inhibitor monotherapy in patients undergoing PCI in different clinical settings. Expert opinion: P2Y₁₂ inhibitor monotherapy after a brief period of DAPT has emerged as an effective approach to reduce the risk of bleeding without any tradeoff in efficacy (i.e., thrombotic complications). This strategy has shown consistent findings in a number of different clinical settings of patients undergoing PCI. Nevertheless, unanswered questions on the ideal patient and the precise P2Y₁₂ monotherapy regimen warrant further investigation.

CYP2C19 genotype-guided antiplatelet therapy: promises and pitfalls

Pharmacogenetic variants can alter the mechanism of action (pharmacodynamic gene variants) or kinetic processes such as absorption, distribution, metabolism and elimination (pharmacokinetic gene variants). Many initial successes in precision medicine occurred in the context of genes encoding the cytochromes P450 (CYP enzymes). CYP2C19 activates the antiplatelet drug clopidogrel, and polymorphisms in the CYP2C19 gene are known to alter the outcome for patients taking clopidogrel in the context of cardiovascular disease. CYP2C19 loss-of-function alleles are specifically associated with increased risk for coronary stent thrombosis and major adverse cardiovascular events in patients taking clopidogrel following percutaneous coronary intervention. We explore successes and challenges encountered as the clinical and scientific communities advance CYP2C19 genotyping in the context of routine patient care.

Novel Mouse Model for Studying Hemostatic Function of Human Platelets

OBJECTIVE

Platelets are critical to the formation of a hemostatic plug and the pathogenesis of atherothrombosis. Preclinical animal models, especially the mouse, provide an important platform to assess the efficacy and safety of antiplatelet drugs. However, these studies are limited by inherent differences between human and mouse platelets and the species-selectivity of many drugs. To circumvent these limitations, we developed a new protocol for the adoptive transfer of human platelets into thrombocytopenic nonobese diabetic/severe combined immune deficiency mice, that is, a model where all endogenous platelets are replaced by human platelets in mice accepting xenogeneic tissues. Approach and Results: To demonstrate the power of this new model, we visualized and quantified hemostatic plug formation and stability by intravital spinning disk confocal microscopy following laser ablation injury to the saphenous vein. Integrin α_IIbβ₃-dependent hemostatic platelet plug formation was achieved within ≈30 seconds after laser ablation injury in humanized platelet mice. Pretreatment of mice with standard dual antiplatelet therapy (Aspirin+Ticagrelor) or PAR1 inhibitor, L-003959712 (an analog of vorapaxar), mildly prolonged the bleeding time and significantly reduced platelet adhesion to the site of injury. Consistent with findings from clinical trials, inhibition of PAR1 in combination with dual antiplatelet therapy markedly prolonged bleeding time in humanized platelet mice.

CONCLUSIONS

We propose that this novel mouse model will provide a robust platform to test and predict the safety and efficacy of experimental antiplatelet drugs and to characterize the hemostatic function of synthetic, stored and patient platelets.

Antithrombotic Treatment After Coronary Intervention: Agreement and Controversy

Percutaneous revascularisation has evolved dramatically in the past few decades. The approach to the management of ischaemic heart disease has changed due to the development of new devices and techniques as well as the availability of new drugs and treatment strategies. Its use in combination with antiplatelet therapies has been essential to protect against stent thrombosis. The length of time this combination therapy is used has been modified in recent years and has been the subject of extensive research. The effect of prolonging the time it is taken or shortening it has been evaluated in different clinical conditions. In practice, the decisions regarding antithrombotic therapy after percutaneous coronary intervention are informed by the patient’s profile and the characteristics of the procedures performed. In this article, we review the use of antiplatelet/anticoagulant therapy after percutaneous coronary intervention focusing on trials and guidelines addressing variable durations for combination regimens and the alternatives.

Involvement of P2 receptors in hematopoiesis and hematopoietic disorders, and as pharmacological targets

Several reports have shown the presence of P2 receptors in hematopoietic stem cells (HSCs). These receptors are activated by extracellular nucleotides released from different sources. In the hematopoietic niche, the release of purines and pyrimidines in the milieu by lytic and nonlytic mechanisms has been described. The expression of P2 receptors from HSCs until maturity is still intriguing scientists. Several reports have shown the participation of P2 receptors in events associated with modulation of the immune system, but their participation in other physiological processes is under investigation. The presence of P2 receptors in HSCs and their ability to modulate this population have awakened interest in exploring the involvement of P2 receptors in hematopoiesis and their participation in hematopoietic disorders. Among the P2 receptors, the receptor P2X7 is of particular interest, because of its different roles in hematopoietic cells (e.g., infection, inflammation, cell death and survival, leukemias and lymphomas), making the P2X7 receptor a promising pharmacological target. Additionally, the role of P2Y12 receptor in platelet activation has been well-documented and is the main example of the importance of the pharmacological modulation of P2 receptor activity. In this review, we focus on the role of P2 receptors in the hematopoietic system, addressing these receptors as potential pharmacological targets.

The Current State of MicroRNAs as Restenosis Biomarkers

In-stent restenosis corresponds to the diameter reduction of coronary vessels following percutaneous coronary intervention (PCI), an invasive procedure in which a stent is deployed into the coronary arteries, producing profuse neointimal hyperplasia. The reasons for this process to occur still lack a clear answer, which is partly why it remains as a clinically significant problem. As a consequence, there is a vigorous need to identify useful non-invasive biomarkers to differentiate and follow-up subjects at risk of developing restenosis, and due to their extraordinary stability in several bodily fluids, microRNA research has received extensive attention to accomplish this task. This review depicts the current understanding, diagnostic potential and clinical challenges of microRNA molecules as possible blood-based restenosis biomarkers.

Antithrombotic Therapy for Percutaneous Cardiovascular Interventions: From Coronary Artery Disease to Structural Heart Interventions

Percutaneous cardiovascular interventions have changed dramatically in recent years, and the impetus given by the rapid implementation of novel techniques and devices have been mirrored by a refinement of antithrombotic strategies for secondary prevention, which have been supported by a significant burden of evidence from clinical studies. In the current manuscript, we aim to provide a comprehensive, yet pragmatic, revision of the current available evidence regarding antithrombotic strategies in the domain of percutaneous cardiovascular interventions. We revise the evidence regarding antithrombotic therapy for secondary prevention in coronary artery disease and stent implantation, the complex interrelation between antiplatelet and anticoagulant therapy in patients undergoing percutaneous coronary intervention with concomitant atrial fibrillation, and finally focus on the novel developments in the secondary prevention after structural heart disease intervention. A special focus on treatment individualization is included to emphasize risk and benefits of each therapeutic strategy.

Time Course of Reendothelialization with Polyzene-F Nanocoated Cobra PzF™ Coronary Stent on Rabbit Iliac Arteries

PURPOSE

Evaluation of reendothelialization with a new thin struts cobalt chromium alloy stent coated with a nano-layer of Polyzene™-F (PzF) in a rabbit iliac artery model.

METHODS

Fifteen stented external rabbit iliac arteries were harvested at Day 7 for electron microscopy analysis following Cobra PzF stents implantation to assess reendothelialization and compare to historical data. Ten additional rabbits were used to assess time course of reendothelialization at 3 and 5 days.

RESULTS

At Day 7, almost complete coverage of endothelial cells was observed with a coverage of 99.54 ± 0.25% of the stented area. No thrombus area was noted. At Day 3, more than half of examined pieces was reendothelialized and reached 78.30 ± 3.7% at Day 5 (p < .01 between each group). All stents were well expanded against the arterial wall and no struts were mal-apposed.

CONCLUSIONS

Reendothelialization was rapid and complete at Day 7. This is the fastest reendothelization process after stenting in this model. No stent occlusion was observed.

Nanoparticle Doped PEDOT for Enhanced Electrode Coatings and Drug Delivery

In order to address material limitations of biologically interfacing electrodes, modified silica nanoparticles are utilized as dopants for conducting polymers. Silica precursors are selected to form a thiol modified particle (TNP), following which the particles are oxidized to sulfonate modified nanoparticles (SNPs). The selective inclusion of hexadecyl trimethylammonium bromide allows for synthesis of both porous and nonporous SNPs. Nonporous nanoparticle doped polyethylenedioxythiophene (PEDOT) films possess low interfacial impedance, high charge injection (4.8 mC cm-2 ), and improved stability under stimulation compared to PEDOT/poly(styrenesulfonate). Porous SNP dopants can serve as drug reservoirs and greatly enhance the capability of conducting polymer-based, electrically controlled drug release technology. Using the SNP dopants, drug loading and release is increased up to 16.8 times, in addition to greatly expanding the range of drug candidates to include both cationic and electroactive compounds, all while maintaining their bioactivity. Finally, the PEDOT/SNP composite is capable of precisely modulating neural activity in vivo by timed release of a glutamate receptor antagonist from coated microelectrode sites. Together, this work demonstrates the feasibility and potential of doping conducting polymers with engineered nanoparticles, creating countless options to produce composite materials for enhanced electrical stimulation, neural recording, chemical sensing, and on demand drug delivery.

Platelet function testing in pigs using the Multiplate® Analyzer

For endovascular research pigs are an established animal model. However, experiences regarding analyses of platelet inhibition in pigs using the Multiplate® Analyzer are limited. The aims of the present study were to investigate if (1) the Multiplate® Analyzer is a suitable method for examination of porcine platelet function using manufacturers’ recommendations for human blood, and (2) platelet inhibition can be induced with acetylsalicylic acid (ASA) and clopidogrel in pigs reliably, and if (3) non-responders to one of the drug can be detected. Additionally we examined differences in (4) the effectiveness of ASA between oral administration and intravenous application, and (5) between domestic pigs (German Landrace; GL) and miniature pigs (MP). We investigated platelet function of 36 unmedicated pigs (GL n = 28; MP n = 8). In addition, 32 blood samples taken from medicated pigs (GL n = 15; MP n = 17) were analysed. Platelet inhibition was induced in four different ways: (1) 500 mg ASA intravenously (n = 11), (2) 500 mg ASA intravenously and 450 mg clopidogrel orally (n = 5), (3) 250 mg ASA orally (n = 11), (4) 250 mg ASA orally and 75 mg clopidogrel orally (n = 5). Results of the ASPI and ADP test of the Multiplate® Analyzer subtests in unmedicated and medicated pigs were in a comparable range to results known from humans. Application of ASA decreased the mean values of the ASPI test significantly regardless of the application method. Joined administration of ASA and clopidogrel also decreased the mean values of the ADP test significantly. Both, oral and intravenous administrations of ASA as well as oral administration of clopidogrel effectively inhibited platelet function in pigs. One pig did not respond to clopidogrel. We found no differences between domestic and miniature pigs regarding reference values in unmedicated pigs and the effectiveness of ASA and clopidogrel.

Incidence of neutropenia in patients with ticlopidine/Ginkgo biloba extract combination drug for vascular events: A post-marketing cohort study

BACKGROUND AND PURPOSE

The ticlopidine/Ginkgo biloba ext. combination drug (Yuclid) is used as an antiplatelet agent for prevention of vascular events since its approval in 2008. The purpose of this study is to explore the safety of ticlopidine/Ginkgo biloba combination, mainly regarding the incidence of neutropenia, through a post-marketing surveillance study.

METHODS

From March 2009 to October 2015, a total of 4839 subjects had been enrolled in this study. The enrollments were conducted by 152 doctors of 89 hospitals according to the regulations for post-marketing surveillance programs in Korea. If a subject was administered the drug once, he/she was included in the safety analysis set for any adverse events and bleedings, and the primary safety evaluation regarding neutropenia was conducted in subjects who completed 3-month blood test follow-up. We predefined that 1% reduction in neutropenia incidence by ticlopidine/Ginkgo biloba ext. combination from the previously reported incidence of ticlopidine of 2.3% was clinically meaningful.

RESULTS

Among the safety analysis set of 4831 patients (99.8% of the enrolled subjects), 3150 (65.1%) completed evaluation for neutropenia at 3 months which is the primary safety endpoint. The major causes of dropout were no follow-up visit at 3 months (n = 1016) and violation of the follow-up period (n = 503). Nine patients experienced neutropenia (Absolute neutrophil count [ANC] ≤ 1200mm3) and the estimated cumulative incidence at 3 months is 0.29% (95% confidence interval, 0.13%- 0.54%). Severe neutropenia (ANC ≤ 450mm3) did not occur in any patients.

CONCLUSIONS

The incidence of neutropenia with addition of Ginkgo biloba ext. to ticlopidine may be lower than the previously reported incidence of neutropenia with ticlopidine, which needs to be confirmed in randomized controlled trials.

Clopidogrel eluting electrospun polyurethane/polyethylene glycol thromboresistant, hemocompatible nanofibrous scaffolds

Biomaterials used as blood-contacting material must be hemocompatible and exhibit lower thrombotic potential while maintaining hemostasis and angiogenesis. With the aim of developing thromboresistant, hemocompatible nanofibrous scaffolds, polyurethane/polyethylene glycol scaffolds incorporated with 1, 5, and 10 wt% Clopidogrel were fabricated and evaluated for their physiochemical properties, biocompatibility, hemocompatibility, and antithrombotic potential. The results of physicochemical characterization revealed the fabrication of nanometer-sized scaffolds with smooth surfaces. The incorporation of both polyethylene glycol and Clopidogrel to polyurethane enhanced the hydrophilicity and water uptake potential of polyurethane/polyethylene glycol/Clopidogrel scaffolds. The dynamic mechanical analysis revealed the enhancement in mechanical strength of the polyurethane/polyethylene glycol scaffolds on incorporation of Clopidogrel. The polyurethane/polyethylene glycol/Clopidogrel scaffolds showed a tri-phasic drug release pattern. The results of hemocompatibility assessment demonstrated the excellent blood compatibility of the polyurethane/polyethylene glycol/Clopidogrel scaffolds, with the developed scaffolds exhibiting lower hemolysis, increased albumin and plasma protein adsorption while reduction in fibrinogen adsorption. Further, the platelet adhesion was highly suppressed and significant increase in coagulation period was observed for Clopidogrel incorporated scaffolds. The results of cell adhesion and cell viability substantiate the biocompatibility of the developed nanofibrous scaffolds with the HUVEC cell viability on polyurethane/polyethylene glycol, polyurethane/polyethylene glycol/Clopidogrel-1, 5, and 10% at day 7 found to be 12.35, 13.36, 14.85, and 4.18% higher as compared to polyurethane scaffolds, and the NIH/3T3 cell viability found to be 35.27, 70.82, 36.60, and 7.95% higher as compared to polyurethane scaffolds, respectively. Altogether the results of the study advocate the incorporation of Clopidogrel to the polyurethane/polyethylene glycol blend in order to fabricate scaffolds with appropriate antithrombotic property, hemocompatibility, and cell proliferation capacity and thus, might be successfully used as antithrombotic material for biomedical application.

Single-session inferior vena cava filter removal, recanalization, and endovenous reconstruction for chronic iliocaval thrombosis

OBJECTIVE

The objective of this study was to demonstrate the safety and efficacy of treatment of inferior vena cava filter (IVCF)-related chronic iliocaval thrombosis with single-session IVCF retrieval and iliocaval recanalization, thereby optimizing stent deployment and avoiding adverse events (AEs) related to stent placement across an obstructed filter.

METHODS

From January 2015 to April 2018, a cohort of 25 consecutive patients presented for treatment of IVCF-related chronic iliocaval thrombosis with filter retrieval, followed by recanalization with stent placement and adjunctive iliofemoral thrombectomy as needed. Inclusion criteria included computed tomography (CT) imaging and clinical presentations consistent with chronic (>30 days) IVCF-related chronic thrombosis. A retrospective analysis of technical success, clinical success as measured with the Venous Clinical Severity Score, use of advanced filter retrieval techniques, and AEs was performed. Primary patency was evaluated with CT at 1 to 3 months and 1 year. Data analysis was performed using a paired t-test.

RESULTS

There were 25 patients (median age, 58.0 years; standard deviation, 15.6 years) with eight types of IVCF encountered; all were treated in a single session. Technical success was achieved in all patients. Mean improvement in the Venous Clinical Severity Score was 1.4 (95% confidence interval, 1.0-1.7; P < .01) in the venous edema subscore and 0.6 (95% confidence interval, 0.2-1.0; P < .01) in the pain subscore. At 1 to 3 months, iliocaval stent patency was maintained in 96% of patients; unilateral iliac vein stent thrombus was seen in one patient. One-year follow-up was available in eight patients, with CT imaging demonstrating maintained patency. Median filter implantation time was 12.3 months (mean, 41.9 months; range, 0.8-245.1 months; standard deviation, 63.3 months). Advanced IVCF retrieval techniques were required for 17 procedures. One major AE and minor AE occurred; no patients died in the study period.

CONCLUSIONS

Single-session iliocaval recanalization with IVCF retrieval has high rates of technical and clinical success in patients with IVCF-related chronic iliocaval thrombosis.