Vascular risk levels affect the predictive value of platelet reactivity for the occurrence of MACE in patients on clopidogrel. Systematic review and meta-analysis of individual patient data

Machine learning insights into thrombo-ischemic risks and bleeding events through platelet lysophospholipids and acylcarnitine species

Coronary artery disease (CAD) often leads to adverse events resulting in significant disease burdens. Underlying risk factors often remain inapparent prior to disease incidence and the cardiovascular (CV) risk is not exclusively explained by traditional risk factors. Platelets inherently promote atheroprogression and enhanced platelet functions and distinct platelet lipid species are associated with disease severity in patients with CAD. Lipidomics data were acquired using mass spectrometry and processed alongside clinical data applying machine learning to model estimates of an increased CV risk in a consecutive CAD cohort (n = 595). By training machine learning models on CV risk measurements, stratification of CAD patients resulted in a phenotyping of risk groups. We found that distinct platelet lipids are associated with an increased CV or bleeding risk and independently predict adverse events. Notably, the addition of platelet lipids to conventional risk factors resulted in an increased diagnostic accuracy of patients with adverse CV events. Thus, patients with aberrant platelet lipid signatures and platelet functions are at elevated risk to develop adverse CV events. Machine learning combining platelet lipidome data and common clinical parameters demonstrated an increased diagnostic value in patients with CAD and might improve early risk discrimination and classification for CV events.

Laboratory Markers of Platelet Production and Turnover

Platelets are formed from bone marrow megakaryocytes, circulate in blood for 7-10 days, and then are destroyed in the spleen and/or liver. Platelet production depends on the megakaryocyte population state in the bone marrow: number and size of the cells. The platelet turnover, i.e., the number of platelets passing through the bloodstream in a certain time, is determined by both the rate of their production and the rate of their destruction. The review considers laboratory markers, which are used to assess platelet production and turnover in the patients with hematologic and cardiovascular pathologies. These markers include some characteristics of platelets themselves: (i) content of reticulated ("young") forms in the blood detected by their staining with RNA dyes; (ii) indicators of the platelet size determined in hematology analyzers (mean volume, percentage of large forms) and in flow cytometers (light scattering level). Alterations of platelet production and turnover lead to the changes in blood plasma concentrations of such molecules as thrombopoietin (TPO, main mediator of megakaryocyte maturation and platelet formation in the bone marrow) and glycocalicin (soluble fragment of the membrane glycoprotein Ib detached from the surface of platelets during their destruction). Specific changes in the markers of platelet production and turnover have been observed in: (i) hypoproductive thrombocytopenias caused by suppression of megakaryocytes in the bone marrow; (ii) immune thrombocytopenias caused by accelerated clearance of the autoantibody-sensitized platelets; and (iii) thrombocytosis (both primary and reactive). The paper presents the data indicating that in patients with cardiovascular diseases an increased platelet turnover and changes in the corresponding markers (platelet size indexes and content of reticulated forms) are associated with the decreased efficacy of antiplatelet drugs and increased risk of thrombotic events, myocardial infarction, and unstable angina (acute coronary syndrome).

Biomarkers for Antiplatelet Therapies in Acute Ischemic Stroke: A Clinical Review

Stroke is one of the world's leading causes of disability and death. Antiplatelet agents are administered to acute ischemic stroke patients as secondary prevention. Clopidogrel involves biotransformation by cytochrome P450 (CYP) enzymes into an active metabolite, and single nucleotide polymorphisms (SNPs) can influence the efficacy of this biotransformation. Despite the therapeutic advantages of aspirin, there is significant inter-individual heterogeneity in response to this antiplatelet drug. In this clinical review, the recent advances in the biomarkers of antiplatelet agents in acute ischemic stroke are discussed. The studies reviewed herein highlight the clinical relevance of antiplatelet resistance, pharmacotherapy of antiplatelet agents predicting drug response, strategies for identifying aspirin resistance, pharmacogenetic variants of antiplatelet agents, miRNAs, and extracellular vesicles (EVs) as biomarkers toward the personalized approach in the management of acute ischemic stroke. The precise pathways contributing to antiplatelet resistance are not very well known but are presumably multi-factorial. It is essential to understand the clinical relevance of clopidogrel and aspirin-related single nucleotide polymorphism (SNPs) as potential predictive and prognostic biomarkers. Prasugrel is a next-generation antiplatelet agent that prevents ADP-platelet activation by binding irreversibly to P2Y12 receptor. There are sporadic reports of prasugrel resistance and polymorphisms in the Platelet endothelial aggregation receptor-1 (PEAR1) that may contribute to a change in the pharmacodynamics response. Ticagrelor, a direct-acting P2Y12-receptor antagonist, is easily absorbed and partly metabolized to major AR-C124910XX metabolite (ARC). Ticagrelor's primary active metabolite, ARC124910XX (ARC), is formed via the most abundant hepatic cytochrome P450 (CYP) enzyme, CYP3A4, and CYP3A5. The integration of specific biomarkers, genotype as well as phenotype-related data in antiplatelet therapy stratification in patients with acute ischemic stroke will be of great clinical significance and could be used as a guiding tool for more effective, personalized therapy.

Endothelial Shear Stress and Platelet FcγRIIa Expression in Intracranial Atherosclerotic Disease

Intracranial atherosclerotic disease (ICAD) has been characterized by the degree of arterial stenosis and downstream hypoperfusion, yet microscopic derangements of endothelial shear stress at the luminal wall may be key determinants of plaque growth, vascular remodeling and thrombosis that culminate in recurrent stroke. Platelet interactions have similarly been a principal focus of treatment, however, the mechanistic basis of anti-platelet strategies is largely extrapolated rather than directly investigated in ICAD. Platelet FcγRIIa expression has been identified as a potent risk factor in cardiovascular disease, as elevated expression markedly increases the risk of recurrent events. Differential activation of the platelet FcγRIIa receptor may also explain the variable response of individual patients to anti-platelet medications. We review existing data on endothelial shear stress and potential interactions with the platelet FcγRIIa receptor that may alter the evolving impact of ICAD, based on local pathophysiology at the site of arterial stenosis. Current methods for quantification of endothelial shear stress and platelet activation are described, including tools that may be readily adapted to the clinical realm for further understanding of ICAD.

Pharmacogenomic polygenic response score predicts ischaemic events and cardiovascular mortality in clopidogrel-treated patients

AIMS

Clopidogrel is prescribed for the prevention of atherothrombotic events. While investigations have identified genetic determinants of inter-individual variability in on-treatment platelet inhibition (e.g. CYP2C19*2), evidence that these variants have clinical utility to predict major adverse cardiovascular events (CVEs) remains controversial.

METHODS AND RESULTS

We assessed the impact of 31 candidate gene polymorphisms on adenosine diphosphate (ADP)-stimulated platelet reactivity in 3391 clopidogrel-treated coronary artery disease patients of the International Clopidogrel Pharmacogenomics Consortium (ICPC). The influence of these polymorphisms on CVEs was tested in 2134 ICPC patients (N = 129 events) in whom clinical event data were available. Several variants were associated with on-treatment ADP-stimulated platelet reactivity (CYP2C19*2, P = 8.8 × 10-54; CES1 G143E, P = 1.3 × 10-16; CYP2C19*17, P = 9.5 × 10-10; CYP2B6 1294 + 53 C > T, P = 3.0 × 10-4; CYP2B6 516 G > T, P = 1.0 × 10-3; CYP2C9*2, P = 1.2 × 10-3; and CYP2C9*3, P = 1.5 × 10-3). While no individual variant was associated with CVEs, generation of a pharmacogenomic polygenic response score (PgxRS) revealed that patients who carried a greater number of alleles that associated with increased on-treatment platelet reactivity were more likely to experience CVEs (β = 0.17, SE 0.06, P = 0.01) and cardiovascular-related death (β = 0.43, SE 0.16, P = 0.007). Patients who carried eight or more risk alleles were significantly more likely to experience CVEs [odds ratio (OR) = 1.78, 95% confidence interval (CI) 1.14-2.76, P = 0.01] and cardiovascular death (OR = 4.39, 95% CI 1.35-14.27, P = 0.01) compared to patients who carried six or fewer of these alleles.

CONCLUSION

Several polymorphisms impact clopidogrel response and PgxRS is a predictor of cardiovascular outcomes. Additional investigations that identify novel determinants of clopidogrel response and validating polygenic models may facilitate future precision medicine strategies.

Assessing platelet reactivity after drug eluting stent implantation: state of the art

Introduction: Platelets play a pivotal role in the occurrence of recurrent ischemic events in coronary artery disease patients who are treated with drug-eluting stents and are on dual antiplatelet therapy (DAPT).Areas covered: High platelet reactivity (HPR) to adenosine diphosphate during clopidogrel therapy is a strong predictor of post-stenting ischemic event occurrences. However, uniform use of potent P2Y₁₂ receptors blockers to overcome HPR is associated with elevated bleeding risk. Selective de-escalation of P2Y₁₂ receptor blocker therapy based on PFT in patients with acute coronary syndrome treated with stenting has been shown to be associated with a similar risk of ischemic event occurrence but with a reduced risk of bleeding. This review aims to discuss the role of PFT in guiding DAPT in patients treated with DES. We searched electronic databases from January 2000 to December 2019 for literatures evaluating the role of platelet function assessment after drug eluting stents.Expert opinion: Platelet function guided therapy improves patient outcomes by lessening bleeding and limiting the overuse of highly potent P2Y₁₂ inhibitors. Interest in this area of de-escalation of therapy will likely grow as the consequences of bleeding are better recognized and the cost of healthcare gains greater focus.

Cost-effectiveness of Platelet Function-Guided Strategy with Clopidogrel or Ticagrelor

Some patients treated with dual antiplatelet therapy (DAPT) following acute coronary syndrome (ACS) can still exhibit heightened residual platelet reactivity (HRPR), which is potentially linked to adverse vascular outcomes. Better tailored DAPT strategies are needed to address this medical need. Aim: To assess the cost-effectiveness of guided DAPT with clopidogrel or ticagrelor in addition to aspirin when using VerifyNow P2Y₁₂ testing in post-ACS patients. Methods: The costs were calculated per 1,000 patients aged >55 years. It was assumed that all patients received either generic clopidogrel or ticagrelor for 1 year, and underwent VerifyNow P2Y₁₂ assay testing before DAPT maintenance. Results: Guided DAPT will prevent five more MIs and six more deaths per 1,000 patients than a standard prescription of generic clopidogrel. The total predictive value of costs per patient is 32% lower if a guided strategy is used than if ticagrelor is given to all patients. Conclusion: Assessment of heightened residual platelet reactivity with P2Y₁₂ assay in triaging DAPT post-ACS patients for 1 year is a cost-effective strategy that would reduce financial burden compared to routine administration of more expensive antiplatelet agents.

Platelet Function Test Use for Patients with Coronary Artery Disease in the Early 2020s

In the field of antithrombotics, precision medicine is of particular interest, as it may lower the incidence of potentially life-threatening side effects. Indeed, antiplatelet drugs such as P2Y₁₂ inhibitors are one of the most common causes of emergency admissions for drug-related adverse events. The last ten years have seen a continuous debate on whether platelet function tests (PFTs) should be used to tailor antiplatelet drugs to cardiovascular patients. Large-scale randomized studies investigating the escalation of antiplatelet therapies according to the results of PFTs were mostly negative. Potent P2Y₁₂ inhibitors are recommended as a first-line treatment in acute coronary syndrome patients, bringing the bleeding risk at the forefront. De-escalation from prasugrel or ticagrelor to clopidogrel is now considered, with or without the use of a PFT. This review covers recent advances in escalation and de-escalation strategies based on PFTs in various clinical settings. It also describes the main features of the most popular platelet function tests as well as the potential added value of genetic testing. Finally, we detail practical suggestions on how PFTs could be used in clinical practice.

Altered functions of platelets during aging

PURPOSE OF REVIEW

Platelets are specialized effector cells that rapidly respond to sites of vascular injury. However, emerging data demonstrate that platelets possess diverse functions that also mediate inflammatory responses and neurological diseases. These functions are relevant to disease processes prevalent among older adults and likely influence susceptibility to thrombotic and inflammatory disorders.

RECENT FINDINGS

Platelet counts decrease in aged individuals whereas platelet reactivity increases. The platelet transcriptome is altered in aged individuals resulting in altered platelet function and exaggerated inflammation. Platelet signaling to monocytes in aging results in significantly more cytokines because of increased platelet-derived granzyme A. Platelet activation in aging appears to be driven, in part, because of increased reactive oxygen species and activation of the mammalian target of rapamycin pathway. Increased platelet hyperactivity in diseases is associated with aging, such cardiovascular disease and sepsis, exaggerate inflammation and thrombosis. Noncanonical functions of platelets influence the development of neurological diseases including Alzheimer's disease.

SUMMARY

Although there have been advances dissecting the molecular mechanisms regarding aging-related changes in platelets, many knowledge gaps still remain. Studies filling these gaps are likely to identify new mechanisms driving aging-related changes in platelet gene expression and function, and contributing to injurious thrombo-inflammation in older adults.

A brief review on resistance to P2Y12 receptor antagonism in coronary artery disease

Background

Platelet inhibition is important for patients with coronary artery disease. When dual antiplatelet therapy (DAPT) is required, a P2Y₁₂-antagonist is usually recommended in addition to standard aspirin therapy. The most used P2Y₁₂-antagonists are clopidogrel, prasugrel and ticagrelor. Despite DAPT, some patients experience adverse cardiovascular events, and insufficient platelet inhibition has been suggested as a possible cause. In the present review we have performed a literature search on prevalence, mechanisms and clinical implications of resistance to P2Y₁₂ inhibitors.

Methods

The PubMed database was searched for relevant papers and 11 meta-analyses were included. P2Y₁₂ resistance is measured by stimulating platelets with ADP ex vivo and the most used assays are vasodilator stimulated phosphoprotein (VASP), Multiplate, VerifyNow (VN) and light transmission aggregometry (LTA).

Discussion/conclusion

The frequency of high platelet reactivity (HPR) during clopidogrel therapy is predicted to be 30%. Genetic polymorphisms and drug-drug interactions are discussed to explain a significant part of this inter-individual variation. HPR during prasugrel and ticagrelor treatment is estimated to be 3–15% and 0–3%, respectively. This lower frequency is explained by less complicated and more efficient generation of the active metabolite compared to clopidogrel. Meta-analyses do show a positive effect of adjusting standard clopidogrel treatment based on platelet function testing. Despite this, personalized therapy is not recommended because no large-scale RCT have shown any clinical benefit. For patients on prasugrel and ticagrelor, platelet function testing is not recommended due to low occurrence of HPR.

Complex Drug-Drug-Gene-Disease Interactions Involving Cytochromes P450: Systematic Review of Published Case Reports and Clinical Perspectives

Drug pharmacokinetics (PK) is influenced by multiple intrinsic and extrinsic factors, among which concomitant medications are responsible for drug-drug interactions (DDIs) that may have a clinical relevance, resulting in adverse drug reactions or reduced efficacy. The addition of intrinsic factors affecting cytochromes P450 (CYPs) activity and/or expression, such as genetic polymorphisms and diseases, may potentiate the impact and clinical relevance of DDIs. In addition, greater variability in drug levels and exposures has been observed when such intrinsic factors are present in addition to concomitant medications perpetrating DDIs. This variability results in poor predictability of DDIs and potentially dramatic clinical consequences. The present review illustrates the issue of complex DDIs using systematically searched published case reports of DDIs involving genetic polymorphisms, renal impairment, cirrhosis, and/or inflammation. Current knowledge on the impact of each of these factors on drug exposure and DDIs is summarized and future perspectives for the management of such complex DDIs in clinical practice are discussed, including the use of advanced Computerized Physician Order Entry (CPOE) systems, the development of model-based dose optimization strategies, and the education of healthcare professionals with respect to personalized medicine.

Acute myocardial infarction occurring while on chronic clopidogrel therapy ('clopidogrel failure') is associated with high incidence of clopidogrel poor responsiveness and stent thrombosis

Objectives

The clinical significance of the laboratory-based phenomenon of clopidogrel hypo-responsiveness and platelet reactivity associated with acute myocardial infarction, despite chronic clopidogrel therapy, is largely unknown. We aimed to determine platelet reactivity and clinical and angiographic features in 29 consecutive patients sustaining an acute myocardial infarction despite chronic (≥1 month) clopidogrel therapy.

Methods

Platelet reactivity was determined on admission using conventional aggregometry. All patients underwent coronary angiography within 24 hours of admission. Patients were matched with clopidogrel-naïve acute myocardial infarction patients. Clopidogrel-naïve patients received a 600 mg clopidogrel loading dose and 75 mg/day thereafter.

Results

Of the 29 study patients, 19 (66%) presented with ST-elevation myocardial infarction, and in 25% the infarction was related to angiographically-proved definite stent thrombosis. Two-thirds of these patients were poor responders to clopidogrel (adenosine diphosphate-induced platelet aggregation >50%) and dual antiplatelet poor responsiveness was found in 57% in the chronic clopidogrel therapy group. Compared with clopidogrel-naïve patients, chronic clopidogrel therapy patients were more likely to demonstrate clopidogrel poor responsiveness (66% versus 38%, p = 0.02), to be diabetic (52% versus 33%, p = 0.1) and to have multi-vessel coronary disease (79% versus 55%, p = 0.03).

Conclusions

Patients sustaining acute coronary syndrome despite chronic clopidogrel therapy are more likely to exhibit inadequate platelet inhibition with clopidogrel.

Genome-wide and candidate gene approaches of clopidogrel efficacy using pharmacodynamic and clinical end points-Rationale and design of the International Clopidogrel Pharmacogenomics Consortium (ICPC)

RATIONALE

The P2Y12 receptor inhibitor clopidogrel is widely used in patients with acute coronary syndrome, percutaneous coronary intervention, or ischemic stroke. Platelet inhibition by clopidogrel shows wide interpatient variability, and high on-treatment platelet reactivity is a risk factor for atherothrombotic events, particularly in high-risk populations. CYP2C19 polymorphism plays an important role in this variability, but heritability estimates suggest that additional genetic variants remain unidentified. The aim of the International Clopidogrel Pharmacogenomics Consortium (ICPC) is to identify genetic determinants of clopidogrel pharmacodynamics and clinical response.

STUDY DESIGN

Based on the data published on www.clinicaltrials.gov, clopidogrel intervention studies containing genetic and platelet function data were identified for participation. Lead investigators were invited to share DNA samples, platelet function test results, patient characteristics, and cardiovascular outcomes to perform candidate gene and genome-wide studies.

RESULTS

In total, 17 study sites from 13 countries participate in the ICPC, contributing individual patient data from 8,829 patients. Available adenosine diphosphate-stimulated platelet function tests included vasodilator-stimulated phosphoprotein assay, light transmittance aggregometry, and the VerifyNow P2Y12 assay. A proof-of-principle analysis based on genotype data provided by each group showed a strong and consistent association between CYP2C19*2 and platelet reactivity (P value=5.1 × 10-40).

CONCLUSION

The ICPC aims to identify new loci influencing clopidogrel efficacy by using state-of-the-art genetic approaches in a large cohort of clopidogrel-treated patients to better understand the genetic basis of on-treatment response variability.

Atherothrombosis and Thromboembolism: Position Paper from the Second Maastricht Consensus Conference on Thrombosis

Atherothrombosis is a leading cause of cardiovascular mortality and long-term morbidity. Platelets and coagulation proteases, interacting with circulating cells and in different vascular beds, modify several complex pathologies including atherosclerosis. In the second Maastricht Consensus Conference on Thrombosis, this theme was addressed by diverse scientists from bench to bedside. All presentations were discussed with audience members and the results of these discussions were incorporated in the final document that presents a state-of-the-art reflection of expert opinions and consensus recommendations regarding the following five topics: 1. Risk factors, biomarkers and plaque instability: In atherothrombosis research, more focus on the contribution of specific risk factors like ectopic fat needs to be considered; definitions of atherothrombosis are important distinguishing different phases of disease, including plaque (in)stability; proteomic and metabolomics data are to be added to genetic information. 2. Circulating cells including platelets and atherothrombosis: Mechanisms of leukocyte and macrophage plasticity, migration, and transformation in murine atherosclerosis need to be considered; disease mechanism-based biomarkers need to be identified; experimental systems are needed that incorporate whole-blood flow to understand how red blood cells influence thrombus formation and stability; knowledge on platelet heterogeneity and priming conditions needs to be translated toward the in vivo situation. 3. Coagulation proteases, fibrin(ogen) and thrombus formation: The role of factor (F) XI in thrombosis including the lower margins of this factor related to safe and effective antithrombotic therapy needs to be established; FXI is a key regulator in linking platelets, thrombin generation, and inflammatory mechanisms in a renin-angiotensin dependent manner; however, the impact on thrombin-dependent PAR signaling needs further study; the fundamental mechanisms in FXIII biology and biochemistry and its impact on thrombus biophysical characteristics need to be explored; the interactions of red cells and fibrin formation and its consequences for thrombus formation and lysis need to be addressed. Platelet-fibrin interactions are pivotal determinants of clot formation and stability with potential therapeutic consequences. 4. Preventive and acute treatment of atherothrombosis and arterial embolism; novel ways and tailoring? The role of protease-activated receptor (PAR)-4 vis à vis PAR-1 as target for antithrombotic therapy merits study; ongoing trials on platelet function test-based antiplatelet therapy adjustment support development of practically feasible tests; risk scores for patients with atrial fibrillation need refinement, taking new biomarkers including coagulation into account; risk scores that consider organ system differences in bleeding may have added value; all forms of oral anticoagulant treatment require better organization, including education and emergency access; laboratory testing still needs rapidly available sensitive tests with short turnaround time. 5. Pleiotropy of coagulation proteases, thrombus resolution and ischaemia-reperfusion: Biobanks specifically for thrombus storage and analysis are needed; further studies on novel modified activated protein C-based agents are required including its cytoprotective properties; new avenues for optimizing treatment of patients with ischaemic stroke are needed, also including novel agents that modify fibrinolytic activity (aimed at plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor.

Reduced Antiplatelet Effect of Aspirin Does Not Predict Cardiovascular Events in Patients With Stable Coronary Artery Disease

Background

Increased platelet aggregation during antiplatelet therapy may predict cardiovascular events in patients with coronary artery disease. The majority of these patients receive aspirin monotherapy. We aimed to investigate whether high platelet‐aggregation levels predict cardiovascular events in stable coronary artery disease patients treated with aspirin.

Methods and Results

We included 900 stable coronary artery disease patients with either previous myocardial infarction, type 2 diabetes mellitus, or both. All patients received single antithrombotic therapy with 75 mg aspirin daily. Platelet aggregation was evaluated 1 hour after aspirin intake using the VerifyNow Aspirin Assay (Accriva Diagnostics) and Multiplate Analyzer (Roche; agonists: arachidonic acid and collagen). Adherence to aspirin was confirmed by serum thromboxane B₂. The primary end point was the composite of nonfatal myocardial infarction, ischemic stroke, and cardiovascular death. At 3‐year follow‐up, 78 primary end points were registered. The primary end point did not occur more frequently in patients with high platelet‐aggregation levels (first versus fourth quartile) assessed by VerifyNow (hazard ratio: 0.5 [95% CI, 0.3–1.1], P=0.08) or Multiplate using arachidonic acid (hazard ratio: 1.0 [95% CI, 0.5–2.1], P=0.92) or collagen (hazard ratio: 1.4 [95% CI, 0.7–2.8], P=0.38). Similar results were found for the composite secondary end point (nonfatal myocardial infarction, ischemic stroke, stent thrombosis, and all‐cause death) and the single end points. Thromboxane B₂ levels did not predict any end points. Renal insufficiency was the only clinical risk factor predicting the primary and secondary end points.

Conclusions

This study is the largest to investigate platelet aggregation in stable coronary artery disease patients receiving aspirin as single antithrombotic therapy. We found that high platelet‐aggregation levels did not predict cardiovascular events.

Individualized dual antiplatelet therapy based on platelet function testing in patients undergoing percutaneous coronary intervention: a meta-analysis of randomized controlled trials

Background

High on-treatment platelet reactivity (HPR) represents a strong risk factor for thrombotic events after PCI. We aim to evaluate the efficacy and safety of individualizing intensified dual antiplatelet therapy (DAPT) in PCI-treated patients with HPR based on platelet function testing (PFT).

Methods

Electronic databases were searched for randomized control trials that reported the clinical outcomes of using an intensified antiplatelet protocol with P2Y₁₂ receptor inhibitor comparing with standard maintenance dose of clopidogrel on the basis of platelet function testing. Clinical endpoints were assessed.

Results

From 2005 to 2016, thirteen clinical studies comprising 7290 patients were included for analysis. Compared with standard antiplatelet therapy with clopidogrel, the intensified protocol based on platelet function testing was associated with a significant reduction in major adverse cardiovascular events (RR:0.55, 95% CI: 0.36–0.84, p = 0.005), cardiovascular death (RR:0.60, 95% CI: 0.38–0.96, p = 0.03), stent thrombosis (RR:0.58, 95% CI: 0.36–0.93, p = 0.02) and target vessel revascularization (RR:0.33, 95% CI: 0.14–0.76, p = 0.009). No significant difference was found in the rate of bleeding events between intensified and standard protocol.

Conclusions

Compared with standard clopidogrel therapy, individualized intensified antiplatelet therapy on the basis of platelet reactivity testing reduces the incidence of cardiovascular events in patient undergoing PCI, without increasing the risk of bleeding.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0582-6) contains supplementary material, which is available to authorized users.

Newly Formed Reticulated Platelets Undermine Pharmacokinetically Short-Lived Antiplatelet Therapies

Supplemental Digital Content is available in the text.

Objective—

Aspirin together with thienopyridine P2Y₁₂ inhibitors, commonly clopidogrel, is a cornerstone of antiplatelet therapy. However, many patients receiving this therapy display high on-treatment platelet reactivity, which is a major therapeutic hurdle to the prevention of recurrent thrombotic events. The emergence of uninhibited platelets after thrombopoiesis has been proposed as a contributing factor to high on-treatment platelet reactivity. Here, we investigate the influences of platelet turnover on platelet aggregation in the face of different dual-antiplatelet therapy strategies.

Approach and Results—

Traditional light transmission aggregometry, cytometry, advanced flow cytometric imaging, and confocal microscopy were used to follow the interactions of populations of platelets from healthy volunteers and patients with stable cardiovascular disease. Newly formed, reticulated platelets overproportionately contributed to, and clustered at, the core of forming aggregates. This phenomenon was particularly observed in samples from patients treated with aspirin plus a thienopyridine, but was absent in samples taken from patients treated with aspirin plus ticagrelor.

Conclusions—

Reticulated platelets are more reactive than older platelets and act as seeds for the formation of platelet aggregates even in the presence of antiplatelet therapy. This is coherent with the emergence of an uninhibited subpopulation of reticulated platelets during treatment with aspirin plus thienopyridine, explained by the short pharmacokinetic half-lives of these drugs. This phenomenon is absent during treatment with ticagrelor, because of its longer half-life and ability to act as a circulating inhibitor. These data highlight the important influences of pharmacokinetics on antiplatelet drug efficacies, especially in diseases associated with increased platelet turnover.