Randomized comparison of a high clopidogrel maintenance dose in patients with diabetes mellitus and coronary artery disease: results of the Optimizing Antiplatelet Therapy in Diabetes Mellitus (OPTIMUS) study

Hyperactivity and Pro-inflammatory Functions of Platelets in Diabetes

Cardiovascular complications claim the lives of up to 70% of patients with diabetes mellitus (DM). The mechanisms increasing cardiovascular risk in DM remain to be fully understood and successfully addressed. Nonetheless, there is increasing evidence in the scientific literature of the participation of platelets in the cardiovascular complications of DM. Multiple reports describe the hyperactivity of platelets in DM and their participation in inflammatory responses. The understanding of the mechanisms underlying the contribution of platelets to cardiovascular pathologies in DM will help the development of targeted therapeutic strategies able to reduce cardiovascular risk in these patients. In this literature review, we summarise our current understanding of the molecular mechanisms leading to the contribution of platelets to cardiovascular risk in DM. Both platelet haemostatic activity leading to thrombus formation and their participation to inflammatory processes are stimulated by the biochemical conditions associated with DM. We also present evidence on how DM affect the efficacy of existing therapeutic treatments for thrombosis and, by converse, how antidiabetic drugs may affect platelet function and the haemostasis/thrombosis balance. Taken together, the growing evidence of the different and unexpected roles of platelets in the progression of DM provides a strong rationale for the design of cardiovascular drugs targeting specifically platelets, their pro-inflammatory activity and their activation mechanisms in this disease. Overall, this article provides an important up-to-date overview of the pathophysiological alterations of platelets in DM, which need to be taken into account for the effective management of cardiovascular health in this disease.

International Consensus Statement on Platelet Function and Genetic Testing in Percutaneous Coronary Intervention: 2024 Update

Current evidence indicates that dual antiplatelet therapy with aspirin plus a P2Y12 inhibitor is essential for the prevention of thrombotic events after percutaneous coronary interventions. However, dual antiplatelet therapy is associated with increased bleeding which may outweigh the benefits. This has set the foundations for customizing antiplatelet treatments to the individual patient. However, bleeding and ischemic risks are often present in the same patient, making it difficult to achieve this balance. The fact that oral P2Y12 inhibitors (clopidogrel, prasugrel, and ticagrelor) have diverse pharmacodynamic profiles that affect clinical outcomes supports the rationale for using platelet function and genetic testing to individualize antiplatelet treatment regimens. Indeed, up to one-third of patients treated with clopidogrel, but a minority of those treated with prasugrel or ticagrelor, exhibit high residual platelet reactivity resulting in an increased thrombotic risk. On the other hand, prasugrel and ticagrelor are frequently associated with low platelet reactivity and increased bleeding risk compared with clopidogrel without providing any additional reduction in ischemic events compared with patients who adequately respond to clopidogrel. The use of platelet function and genetic testing may allow for a guided selection of oral P2Y12 inhibitors. However, the nonuniform results of randomized controlled trials have led guidelines to provide limited recommendations on the implementation of these tests in patients undergoing percutaneous coronary intervention. In light of recent advancements in the field, this consensus document by a panel of international experts fills in the guideline gap by providing updates on the latest evidence in the field as well as recommendations for clinical practice.

CYP2C19 Genetic Testing for Oral P2Y12 Inhibitor Therapy: A Scientific Statement From the American Heart Association

There is significant variability in the efficacy and safety of oral P2Y12 inhibitors, which are used to prevent ischemic outcomes in common diseases such as coronary and peripheral arterial disease and stroke. Clopidogrel, a prodrug, is the most used oral P2Y12 inhibitor and is activated primarily after being metabolized by a highly polymorphic hepatic cytochrome CYP2C219 enzyme. Loss-of-function genetic variants in CYP2C219 are common, can result in decreased active metabolite levels and increased on-treatment platelet aggregation, and are associated with increased ischemic events on clopidogrel therapy. Such patients can be identified by CYP2C19 genetic testing and can be treated with alternative therapy. Conversely, universal use of potent oral P2Y12 inhibitors such as ticagrelor or prasugrel, which are not dependent on CYP2C19 for activation, has been recommended but can result in increased bleeding. Recent clinical trials and meta-analyses have demonstrated that a precision medicine approach in which loss-of-function carriers are prescribed ticagrelor or prasugrel and noncarriers are prescribed clopidogrel results in reducing ischemic events without increasing bleeding risk. The evidence to date supports CYP2C19 genetic testing before oral P2Y12 inhibitors are prescribed in patients with acute coronary syndromes or percutaneous coronary intervention. Clinical implementation of such genetic testing will depend on among multiple factors: rapid availability of results or adoption of the concept of performing preemptive genetic testing, provision of easy-to-understand results with therapeutic recommendations, and seamless integration in the electronic health record.

Perioperative platelet reactivity over time in patients undergoing vascular surgery: An observational pilot study

BACKGROUND

Despite Antiplatelet therapy (APT), cardiovascular patients undergoing revascularisation remain at high risk for thrombotic events. Individual response to APT varies substantially, resulting in insufficient protection from thrombotic events due to high on-treatment platelet reactivity (HTPR) in ≤40% of patients. Individual variation in platelet response impairs APT guidance on a single patient level. Unfortunately, little is known about individual platelet response to APT over time, timing for accurate residual platelet reactivity measurement, or the optimal test to monitor residual platelet reactivity.

AIMS

To investigate residual platelet reactivity variability over time in individual patients undergoing carotid endarterectomy (CEA) treated with clopidogrel.

METHODS

Platelet reactivity was determined in patients undergoing CEA in a prospective, single-centre, observational study using the VerifyNow (change in turbidity from ADP-induced binding to fibrinogen-coated beads), the VASP assay (quantification of phosphorylation of vasodilator-stimulated phosphoprotein), and a flow-cytometry-based assay (PACT) at four perioperative time points. Genotyping identified slow (CYP2C19*2 and CYP2C19*3) and fast (CYP2C19*17) metabolisers.

RESULTS

Between December 2017 and November 2019, 50 patients undergoing CEA were included. Platelet reactivity measured with the VerifyNow (p = < .001) and VASP (p = .029) changed over time, while the PACT did not. The VerifyNow identified patients changing HTRP status after surgery. The VASP identified patients changing HTPR status after eight weeks (p = .018). CYP2C19 genotyping identified 13 slow metabolisers.

CONCLUSION

In patients undergoing CEA, perioperative platelet reactivity measurements fluctuate over time with little agreement between platelet reactivity assays. Consequently, HTPR status of individual patients measured with the VerifyNow and VASP assay changed over time. Therefore, generally used perioperative platelet reactivity measurements seem unreliable for adjusting perioperative APT strategy.

Effects of intravenous lysine acetylsalicylate versus oral aspirin on platelet responsiveness in patients with ST-segment elevation myocardial infarction: the ECCLIPSE-STEMI trial

Prasugrel and ticagrelor, new P2Y12-ADP receptor antagonists, are associated with greater pharmacodynamic inhibition and reduction of cardiovascular events in patients with an acute coronary syndrome. However, evidence is lacked about the effects of achieving faster and stronger cyclooxygenase inhibition with intravenous lysine acetylsalicylate (LA) compared to oral aspirin. Recently, we demonstrated in healthy volunteers that the administration of intravenous LA resulted in a significantly reduction of platelet reactivity compared to oral aspirin. Loading dose of LA achieves platelet inhibition faster, and with less variability than aspirin. However, there are no data of this issue in patients with an ST-segment elevation myocardial infarction (STEMI). This is a prospective, randomized, multicenter, open platelet function study conducted in STEMI patients. Subjects were randomly assigned to receive a loading dose (LD) of intravenous LA 450 mg plus oral ticagrelor 180 mg, or LD of aspirin 300 mg plus ticagrelor 180 mg orally. Platelet function was evaluated at baseline, 30 min, 1 h, 4 h and 24 h using multiple electrode aggregometry and vasodilator-stimulated phosphoprotein phosphorylation (VASP). The primary endpoint of the study is the inhibition of platelet aggregation (IPA) after arachidonic acid (AA) 0.5 mM at 30 min. Secondary endpoints were the IPA at 1, 4, and 24 h after AA, and non-AA pathways through the sequence (ADP and TRAP). A total of 32 STEMI patients were randomized (16 LA, 16 aspirin). The inhibition of platelet aggregation after AA 0.5 mM at 30 min was greater in subjects treated with LA compared with aspirin: 166 vs. 412 respectively (p = 0.001). This differential effect was observed at 1 h (p = 0.01), but not at 4 and 24 h. Subjects treated with LA presented less variability and faster inhibition of platelet aggregation wit AA compared with aspirin. The administration of intravenous LA resulted in a significantly reduction of platelet reactivity compared to oral aspirin on ticagrelor inhibited platelets in patients with STEMI. Loading dose of LA achieves an earlier platelet inhibition, and with less variability than aspirin.Trial Registration: Unique identifier: NCT02929888; URL: http://www.clinicaltrials.gov.

Ideal P2Y12 Inhibitor in Acute Coronary Syndrome: A Review and Current Status

Dual antiplatelet therapy (DAPT) has remained the cornerstone for management of acute coronary syndrome (ACS) over the years. Clopidogrel has been the quintessential P2Y12 receptor (platelet receptor for Adenosine 5' diphosphate) inhibitor for the past two decades. With the demonstration of unequivocal superior efficacy of prasugrel/ticagrelor over clopidogrel, guidelines now recommend these agents in priority over clopidogrel in current management of ACS. Cangrelor has revived the interest in injectable antiplatelet therapy too. Albeit the increased efficacy of these newer agents comes at the cost of increased bleeding and this becomes more of a concern when combined with aspirin. Which P2Y12i is superior over another has been intensely debated over last few years after the ISAR-REACT 5 study with inconclusive data. Three novel antiplatelet agents are already in the pipeline for ACS with all of them succeeding in phase II studies. The search for an ideal antiplatelet remains a need of the hour for optimal reduction of ischemic events in ACS.

Cardiovascular disease in type 2 diabetes mellitus: progress toward personalized management

Cardiovascular diseases (CVDs) are the main cause of death among patients with type 2 diabetes mellitus (T2DM), particularly in low- and middle-income countries. To effectively prevent the development of CVDs in T2DM, considerable effort has been made to explore novel preventive approaches, individualized glycemic control and cardiovascular risk management (strict blood pressure and lipid control), together with recently developed glucose-lowering agents and lipid-lowering drugs. This review mainly addresses the important issues affecting the choice of antidiabetic agents and lipid, blood pressure and antiplatelet treatments considering the cardiovascular status of the patient. Finally, we also discuss the changes in therapy principles underlying CVDs in T2DM.

Phosphoinositide 3-Kinases as Potential Targets for Thrombosis Prevention

As integral parts of pathological arterial thrombi, platelets are the targets of pharmacological regimens designed to treat and prevent thrombosis. A detailed understanding of platelet biology and function is thus key to design treatments that prevent thrombotic cardiovascular disease without significant disruption of the haemostatic balance. Phosphoinositide 3-kinases (PI3Ks) are a group of lipid kinases critical to various aspects of platelet biology. There are eight PI3K isoforms, grouped into three classes. Our understanding of PI3K biology has recently progressed with the targeting of specific isoforms emerging as an attractive therapeutic strategy in various human diseases, including for thrombosis. This review will focus on the role of PI3K subtypes in platelet function and subsequent thrombus formation. Understanding the mechanisms by which platelet function is regulated by the various PI3Ks edges us closer toward targeting specific PI3K isoforms for anti-thrombotic therapy.

Acute coronary syndromes in diabetic patients, outcome, revascularization, and antithrombotic therapy

Diabetes exacerbates the progression of atherosclerosis and is associated with increased risk of developing acute coronary syndrome (ACS). Approximatively 25-30% of patients admitted for ACS have diabetes. ACS occurs earlier in diabetics and is associated with increased mortality and a higher risk of recurrent ischemic events. An increased proinflammatory and prothrombotic state is involved in the poorer outcomes of diabetic patients. In the past decade advancement in both percutaneous coronary intervention (PCI) and coronary artery by-pass graft (CABG) techniques and more potent antiplatelet drugs like prasugrel and ticagrelor improved outcomes of diabetic patients with ACS, but this population still experiences worse outcomes compared to non-diabetic patients. While in ST elevation myocardial infarction urgent PCI is the method of choice for revascularization, in patients with non-ST elevation ACS an early invasive approach is suggested by the guidelines, but in the setting of multivessel (MV) or complex coronary artery disease (CAD) the revascularization strategy is less clear. This review describes the accumulating evidence regarding factors involved in promoting increased incidence and poor prognosis of ACS in patients with diabetes, the evolution over time of prognosis and outcomes, revascularization strategies and antithrombotic therapy studied until now.

Impact of Diabetes on Platelet Function in Acute Ischemic Stroke Patients Taking Dual Antiplatelet Therapy

Objectives: Diabetes mellitus (DM) is a significant risk factor for ischemic stroke and associated with platelet reactivity. We aim to evaluate the effect of DM on platelet function in acute ischemic stroke patients taking dual antiplatelet therapy (DAPT).

Methods: We consecutively included patients with acute ischemic stroke taking DAPT. Platelet function was assessed by thromboelastography and the arachidonic acid (AA) or adenosine diphosphate (ADP) induced platelet inhibition rate were used to confirmed the high-residual on-treatment platelet reactivity (HRPR) to aspirin or clopidogrel. We classified patients into DM and non-DM groups. The association between DM and platelet function was assessed and the confounding factors were adjusted by propensity score matching (PSM) analysis. The independent risk factors of HRPR were determined by multivariate logistic regression analysis.

Results: A total of 1,071 acute ischemic stroke patients, 712 in the non-DM group and 359 in the DM group, were included. Patients with DM had a significantly higher maximum amplitude (63.0 vs. 62.0 mm, P < 0.01), ADP-induced clot strength (34.6 vs. 30.3 mm, P < 0.01) and clopidogrel HRPR rate (22.6% vs. 17.3%, P = 0.038) than those without DM. Among 662 patients after PSM, the maximum amplitude (63.1 vs. 62.5 mm, P = 0.032), ADP-induced clot strength (34.6 vs. 29.3 mm, P < 0.01) and clopidogrel HRPR rate (23.0% vs. 15.7%, P = 0.018) is still higher in the DM group. DM was an independent factor of clopidogrel HRPR (OR = 1.48, 95% CI: 1.03–2.07, P < 0.05).

Conclusions: In acute ischemic stroke patients taking DAPT, DM is associated with increased platelet reactivity and higher prevalence of clopidogrel HRPR.

Intensified antiplatelet therapy in patients after percutaneous coronary intervention with high on-treatment platelet reactivity: the OPTImal Management of Antithrombotic Agents (OPTIMA)-2 Trial

High on-treatment platelet reactivity (HOPR) is associated with increased risk of cardiovascular events in patients undergoing percutaneous coronary intervention (PCI). We randomised post-PCI patients with HOPR after 5 days of standard dual antiplatelet therapy (DAPT) to intensified therapy with aspirin 100 mg once daily in combination with either clopidogrel 150 mg once daily, clopidogrel 75 mg once daily plus cilostazol 100 mg twice daily, ticagrelor 90 mg twice daily, or standard therapy with clopidogrel 75 mg once daily (STD) for 1 month, after which all patients were switched to standard DAPT for a further 11 months. The primary outcome was residual HOPR rate at 1 month. We screened 1724 patients with light transmission aggregation studies and randomised 434 with HOPR. At 1 month the proportion of patients with persistent HOPR was significantly lower in the intensified therapy groups compared with STD group. Compared to the group receiving STD therapy, those receiving intensified therapy had significantly lower rate of major adverse cardiovascular events (MACE) at both 1 month and 12 months with no significant increase in bleeding. In patients with post-PCI HOPR, 1 month of intensified antiplatelet therapy provides greater platelet inhibition and improves outcomes without increasing bleeding. Clinical Trial Registration URL: http://www.clinicaltrials.gov; Unique Identifier: NCT01955200.

PharmVar GeneFocus: CYP2C19

The Pharmacogene Variation Consortium (PharmVar) catalogues star (*) allele nomenclature for the polymorphic human CYP2C19 gene. CYP2C19 genetic variation impacts the metabolism of many drugs and has been associated with both efficacy and safety issues for several commonly prescribed medications. This GeneFocus provides a comprehensive overview and summary of CYP2C19 and describes how haplotype information catalogued by PharmVar is utilized by the Pharmacogenomics Knowledgebase and the Clinical Pharmacogenetics Implementation Consortium (CPIC).

Impact of Neointimal Condition and Platelet Reactivity on Intrastent Thrombus at Long-Term Follow-up After 2nd- and 3rd-Generation Drug-Eluting Stent Implantation - Insights From a Coronary Angioscopy and Pharmacodynamic Study

BACKGROUND

Although the incidence of very late stent failure (VLSF) is reduced with newer generation drug-eluting stent (DES), the mechanism of VLSF has not been fully explored.

METHODS AND RESULTS

This study evaluated both local vascular healing using coronary angioscopy and systemic factors determined by platelet reactivity at long-term follow-up after 2nd- and 3rd-generation DES implantation in patients with acute coronary syndrome. Coronary angioscopy was performed to assess neointimal coverage (NIC), yellow color (YC) grade and presence of thrombus. The obtained findings were compared with 2nd- and 3rd-DES. Platelet aggregation was assessed by light transmittance aggregometry. 100 consecutive patients were prospectively enrolled: 2nd- (n=50) and 3rd-DES (n=50). 3rd-DES patients had significantly higher NIC grade and lower YC grade compared with 2nd-DES. The presence of thrombus was tended to be lower with 3rd-DES than with 2nd-DES (8% vs. 18%, P=0.11). Patients with thrombus had significantly higher maximum platelet aggregation and higher prevalence of high on-treatment platelet reactivity (HPR) than those without thrombus. Multivariable analysis showed stent strut exposure and HPR as independent predictors of thrombus.

CONCLUSIONS

Newer generation DES contribute to better vascular healing depending on the degree of neointimal coverage. In addition to local factors at the stented lesion, systemic factors such as degree of platelet reactivity might also contribute to VLSF.

Increased Intraplatelet ADMA Level May Promote Platelet Activation in Diabetes Mellitus

Background

Antiplatelet therapy has become a standard therapeutic approach in the secondary prevention of cardiovascular system disorders of thrombotic origin. Patients with concomitant diabetes mellitus (DM) obtain fewer benefits from this treatment. Hence, the pathophysiology of altered platelet function in response to glucose metabolism impairment should be of particular interest.

Objectives

The aim of our study was to verify if the platelet expression of the asymmetric dimethylarginine (ADMA) in diabetic patients differs in comparison to the nondiabetic ones. The correlation of platelet-ADMA with platelet activation and aggregation as well as with other risk factors was also investigated. Material and Methods. A total of 61 subjects were enrolled in this study, including thirty-one type 2 diabetic subjects without diabetes-related organ damage. Physical examination was followed by blood collection with an assessment of platelet aggregation, traditional biochemical cardiovascular risk factors, and evaluation of nitric oxide bioavailability parameters in plasma and thrombocytes. Subsequently, the assessment of endothelial function using Peripheral Arterial Tonometry and Laser Doppler Flowmetry (LDF) was performed.

Results

In the DM group, elevated concentration of intraplatelet ADMA and higher ADMA/SDMA ratio compared to the control group was observed. It was accompanied by higher ADP-mediated platelet aggregation and lower microvascular response to a local thermal stimulus measured by LDF in the diabetes group.

Conclusions

Type 2 diabetes is related to higher intraplatelet concentration of asymmetric dimethylarginine (ADMA), which may result in impaired platelet-derived nitric oxide synthesis and subsequent increased platelet activity, as assessed by the ADP-induced aggregation. Laser Doppler Flowmetry, compared to EndoPAT 2000, appears to be a more sensitive indicator of the impaired microvasculature vasodilation in diabetics without the presence of clinically significant target organ damage.

The Effect of Diabetes on Prognosis Following Myocardial Infarction Treated with Primary Angioplasty and Potent Antiplatelet Therapy

PURPOSE

To investigate the prognostic significance of diabetes mellitus (DM) in patients with high risk acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (pPCI) in the era of potent antithrombotics.

METHODS

Data from 1230 ST-segment elevation myocardial infarction (STEMI) patients enrolled in the PRAGUE-18 (prasugrel vs. ticagrelor in pPCI) study were analyzed. Ischemic and bleeding event rates were calculated for patients with and without diabetes. The independent impact of diabetes on outcomes was evaluated after adjustment for outcome predictors.

RESULTS

The prevalence of DM was 20% (N = 250). Diabetics were older and more often female. They were more likely to have hypertension, hyperlipoproteinemia, multivessel coronary disease and left main disease, and be obese. The primary net-clinical endpoint (EP) containing death, spontaneous nonfatal MI, stroke, severe bleeding, and revascularization at day 7 occurred in 6.1% of patients with, and in 3.5% of patients without DM (HR 1.8; 95% CI 0.978-3.315; P = 0.055). At one year, the key secondary endpoint defined as cardiovascular death, spontaneous MI, or stroke occurred in 8.8% with, and 5.5% without DM (HR 1.621; 95% CI 0.987-2.661; P = 0.054). In those with DM the risk of total one-year mortality (6.8% vs. 3.9% (HR 1.773; 95% CI 1.001-3.141; P = 0.047)) and the risk of nonfatal reinfarction (4.8% vs. 2.2% (HR 2.177; 95% CI 1.077-4.398; P = 0.026)) were significantly higher compared to in those without DM. There was no risk of major bleeding associated with DM (HR 0.861; 95% CI 0.554-1.339; P = 0.506). In the multivariate analysis, diabetes was independently associated with the one-year risk of reinfarction (HR 2.176; 95% Confidence Interval, 1.055-4.489; p = 0.035).

CONCLUSION

Despite best practices STEMI treatment, diabetes is still associated with significantly worse prognoses, which highlights the importance of further improvements in the management of this high-risk population.

Long-term effect of clopidogrel in patients with and without diabetes: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Previous studies have shown that patients with diabetes mellitus (DM) respond poorly to clopidogrel treatment.

AIM

To systematically evaluate the efficacy of clopidogrel for the treatment of acute coronary syndromes or ischemic stroke in patients with or without DM.

METHODS

PubMed, the Cochrane Central Register of Controlled Trials, and EMBASE were searched from 1980 on 27 June 2019 to identify relevant randomized controlled trials that compared the effect of a combination of clopidogrel and aspirin with aspirin alone. A random-effects meta-analysis was used to estimate the hazard ratio (HR) and its 95% confidence interval (CI). Sensitivity analysis was performed using a fixed-effect model. The I 2 statistic was used to evaluate the heterogeneity of the study data.

RESULTS

Six randomized controlled trials, comprising 43352 participants (13491 with and 29861 without DM) who had received antiplatelet therapy for ≥ 3 mo, were included in the meta-analysis. Compared with aspirin alone, a combination of clopidogrel and aspirin significantly reduced the risk of any cardiovascular event in patients without DM (HR = 0.78, 95%CI: 0.71-0.86, P < 0.001; I 2 = 23%, P = 0.26). Clopidogrel plus aspirin also significantly reduced cardiovascular risk in patients with DM, although the effect was smaller (HR = 0.89, 95%CI: 0.81-0.99, P = 0.030; I 2 = 0%, P = 0.74). Nevertheless, there was no significant difference in the efficacy of clopidogrel at reducing the risk of cardiovascular events in patients with DM vs those without (P for interaction = 0.062).

CONCLUSION

Thus, the present study shows that the addition of clopidogrel to aspirin significantly lowers cardiovascular risk in patients with or without DM who have experienced ischemic cardiovascular disease. The beneficial effect of the addition of clopidogrel to aspirin for patients with DM was lower than that in patients without DM, although the modifying effect of DM did not reach significance.

Incremental role of glycaemic variability over HbA1c in identifying type 2 diabetic patients with high platelet reactivity undergoing percutaneous coronary intervention

BACKGROUND

Diabetic patients with on-treatment high platelet reactivity (HPR) show an increased risk of thrombotic events. Whether measuring glycated haemoglobin (HbA1c) levels and/or glycaemic variability (GV) may help identifying diabetic patients at higher risk deserving tailored antiplatelet and/or glucose lowering strategies is unknown. We aimed to investigate the relationship between GV, HbA1c levels and platelet reactivity in patients with type 2 diabetes mellitus (DM) undergoing percutaneous coronary intervention (PCI).

METHODS

Platelet reactivity was measured in type 2 DM patients using VerifyNow P2Y12 assay. HPR was defined as P2Y12 Reaction Unit (PRU) > 240. GV was expressed through mean amplitude of glycaemic excursions (MAGE) and coefficient of variance (CV) by using the iPro™ continuous glucose recorder.

RESULTS

Thirty-five patients (age 70 ± 9 years, 86% male, mean HbA1c 7.2 ± 1.0%) on clopidogrel therapy were enrolled. HbA1c was independently associated with HPR (OR 7.25, 95% CI 1.55-33.86, p = 0.012). Furthermore, when factored into the model, GV indexes provided independent (OR 1.094, 95% CI 1.007-1.188, p < 0.034) and additional (p < 0.001) diagnostic significance in identifying diabetic patients with HPR.

CONCLUSIONS

Glyco-metabolic state significantly correlates with HPR in well-controlled type 2 DM patients on clopidogrel therapy. HbA1c identifies patients at higher thrombotic risk but the highest diagnostic accuracy is achieved by combining GV and HbA1c. Whether individualized antithrombotic and glucose-lowering therapies based on the assessment of these parameters may reduce the incidence of thrombotic events in patients undergoing PCI should be further investigated.

The Efficacy of P2Y12 Reactive Unit to Predict the Periprocedural Thromboembolic and Hemorrhagic Complications According to Clopidogrel Responsiveness and Safety of Modification of Dual Antiplatelet Therapy : A Meta-Analysis

The efficacy of P2Y12 reaction unit (PRU) of VerifyNow still remains as a controversial issue in neurointervention. So we investigated the usefulness of PRU of VerifyNow to predict the peri-procedural thromboembolic events (TE) and hemorrhagic events (HE). And we evaluated the safety of modified dual antiplatelet therapy (DAPT) or triple antiplatelet therapy (TAPT) for clopidogrel hyporesponders. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science and Scopus on August 19 2018. Data was collected the 1) incidence of TE between clopidogrel responder and clopidogrel hypo-responder, 2) incidence of HE between clopidogrel hyper-responder and clopidogrel responder and hypo-responder, and 3) incidence of TE and HE between modified DAPT or TAPT and standard DAPT in clopidogrel hypo-responder. High cut-off value of PRU was defined as PRU >40% or <220. Fifteen studies were enrolled. Clopidogrel responder showed lower incidence of TE than hypo-responder (risk ratio [RR], 0.32; 95% confidence interval [CI], 0.17-0.61; p<0.001). With the high cut-off value of PRU, clopidogrel responder showed more lower incidence of TE than hypo-responder (RR, 0.11; 95% CI, 0.02-0.45; p=0.002). The incidence of periprocedural HE have higher on clopidogrel hyper-responder than clopidogrel responder and hypo-responder (RR, 4.26; 95% CI, 1.10-16.44; p=0.04; I2=66%). The incidence of periprocedural TE after changing regimen of DAPT for clopidogrel hypo-responder have a tendency to reduce, but there was no significant difference between modified DAPT or TAPT group and standard DAPT group (p>0.05). The incidence of periprocedural HE after changing regimen of DAPT for clopidogrel hypo-responder was no significant difference between modified DAPT or TAPT group and standard DAPT group (p>0.05). PRU is a useful tool as a predictor of peri-procedural TE or HE on neurointervention. PRU has a threshold effect of cut-off value to predict the peri-procedural TE. Modified DAPT or TAPT to prevent TE in clopidogrel hypo-responders could not reduce the incidence of TE. We should investigate the further research about modification of regiment on neurointervention.

Medical Therapy for Long-Term Prevention of Atherothrombosis Following an Acute Coronary Syndrome: JACC State-of-the-Art Review

Following an acute coronary syndrome (ACS), heightened predisposition to atherothrombotic events may persist for years. Advances in understanding the pathobiology that underlies this elevated risk furnish a mechanistic basis for devising long-term secondary prevention strategies. Recent progress in ACS pathophysiology has challenged the focus on single "vulnerable plaques" and shifted toward a more holistic consideration of the "vulnerable patient," thus highlighting the primacy of medical therapy in secondary prevention. Despite current guideline-directed medical therapy, a consistent proportion of post-ACS patients experience recurrent atherothrombosis due to unaddressed "residual risk": contemporary clinical trials underline the pivotal role of platelets, coagulation, cholesterol, and systemic inflammation and provide a perspective on a personalized, targeted approach. Emerging data sheds new light on heretofore unrecognized residual risk factors. This review aims to summarize evolving evidence relative to secondary prevention of atherothrombosis, with a focus on recent advances that promise to transform the management of the post-ACS patient.

Enhanced Platelet Response to Clopidogrel in Zucker Diabetic Fatty Rats due to Impaired Clopidogrel Inactivation by Carboxylesterase 1 and Increased Exposure to Active Metabolite

Clopidogrel (Clop), a thienopyridine antiplatelet prodrug, is metabolized by cytochrome P450s (CYPs) to an active metabolite, Clop-AM, and hydrolyzed by carboxylesterase (CES)1 to the inactive Clop-acid. Patients with type 2 diabetes (T2DM) tend to have a poor response to Clop due to reduced generation of Clop-AM. Whether a similar response occurs in the Zucker diabetic fatty (ZDF) rat, a commonly used animal model of T2DM, has not been explored. In this work, we compared ZDF and control rats for hepatic CES1- and CYP-mediated Clop metabolism; pharmacokinetics of Clop, Clop-AM, and Clop-acid; and the antiplatelet efficacy of Clop. In contrast to clinical findings, Clop-treated ZDF rats displayed significantly less (50%) maximum platelet aggregation at 4 hours than control rats; the enhanced efficacy was accompanied by higher formation of Clop-AM and lower formation of Clop-acid. In vitro studies showed that hepatic levels of CES1 protein and activity and Ces1e mRNA were significantly lower in ZDF than in control rats, as were the mRNA levels of CYP2B1/2, CYP2C11, and CYP3A2, and levels of CYP2B6-, CYP2C19-, and CYP3A4-related proteins and enzymatic activities in liver microsomes of ZDF rats. Interestingly, liver microsomes of ZDF rats produced higher levels of Clop-AM than that of control rats despite their lower CYP levels, although the addition of fluoride ion, an esterase inhibitor, enhanced Clop-AM formation in control rats more than in ZDF rats. These results suggest that the reduction in CES1-based Clop inactivation indirectly enhances Clop efficacy in ZDF rats by making more Clop available for CYP-mediated Clop-AM formation.

The prognostic value of multiple electrode aggregometry and light transmittance aggregometry in stable cardiovascular patients with type 2 diabetes mellitus

AIM

Limited data are available regarding the clinical relevance of platelet function measurements in stable patients with coronary artery disease (CAD). Our aim is to evaluate the agreement between multiple electrode aggregometry (MEA) and light transmittance aggregometry (LTA) in detecting clopidogrel low responders and their prognostic value in CAD patients with type 2 diabetes mellitus (T2DM) on dual platelet inhibition.

METHODS

LTA and MEA were performed in 122 stable cardiovascular patients with T2DM. The upper quartile of patients according to maximum LTA (LTAmax) and MEA measurements were defined as clopidogrel low responders. Agreement between the two methods was evaluated by kappa statistics. We assessed the potential correlation between antiplatelet response and clinical outcome and the optimal cutoff value according to ROC analysis to predict the occurrence of major adverse cardiovascular events (MACE), during 1-year follow-up period.

RESULTS

Cohen's kappa coefficients (0.214) indicated fair agreement (70.2%) between LTA and MEA. A total of 25 MACE occurred in 108 patients (23.1%). Patients with MACE had higher LTAmax than those without (57.1 ± 16.5 vs 49.3 ± 18.3, respectively, p = 0.023). MEA measurements were similar between patients with and without MACE (30.1 ± 15.4 vs 30.6 ± 20.8, respectively; p = 0.84). Multiple logistic regression showed LTAmax response as an independent predictor of death from cardiovascular causes (Odds Ratio, adjusted:0.2;0.05-0.81). ROC analysis indicated that LTAmax cutoff of 62.5% best predicted death (AUC = 0.67, sensitivity = 78%, specificity = 61.5%).

CONCLUSIONS

The assessment of platelet responsiveness remains highly test-specific. Our results support the prognostic role of LTA, but not MEA testing, for death risk evaluation in stable cardiovascular T2DM patients.

Statins significantly reduce mortality in patients receiving clopidogrel without affecting platelet activation and aggregation: a systematic review and meta-analysis

BACKGROUND

Combination of statins and clopidogrel is frequently administered in patients with coronary artery disease (CAD). They are mainly activated and eliminated in the liver by cytochrome P450 isoenzyme 3A4 (CYP3A4). The aim was to clarify whether the coadministration of clopidogrel and statins attenuate respective efficacy.

METHODS

PubMed, Embase, the Cochrane Library, Web of Science and Clinical Trials. gov were searched for until August 2018. Randomized controlled trials (RCTs) and cohort studies were taken into quality evaluation. Data were pooled using random effect models to estimate standard mean difference (SMD) or risk ratio (RR) with 95% confidence interval (CI).

RESULTS

In total, 28 studies representing 25,267 participants were included. Statins reduce the mortality of patients administered clopidogrel (RR 0.54; 95% CI 0.40,0.74; p = 0.000), no differences were found in platelet aggregation (PA) (SMD 0.02; 95% CI -0.38,0.42; p = 0.920) and the expressions of P-selectin (SMD -0.04; 95% CI -0.14,0.05; p = 0.346), CD40L (SMD 0.09; 95% CI -0.29,0.48; p = 0.633), CD63 (SMD 0.09; 95% CI -0.01,0.19; p = 0.079) and PAC-1 (SMD 0.03; 95% CI -0.08,0.13; p = 0.633). Furthermore, CYP3A4 metabolized or non-CYP3A4 metabolized statins have no discrepancies in PA (SMD 0.13; 95% CI -0.31,0.58; p = 0.556), P-selectin (SMD 0.17; 95% CI -0.16,0.51; p = 0310), death (RR 0.89; 95% CI 0.38,2.07; p = 0.791), except for triglyceride (TG) (SMD -0.19; 95% CI -0.33,-0.06; p = 0.005).

CONCLUSIONS

This meta-analysis confirmed that statins reduce mortality in patients undergoing clopidogrel treatment without affecting platelet activation and aggregation.

Diabetes and antiplatelet therapy: from bench to bedside

Diabetes mellitus (DM) is a metabolic disorder associated with accelerated atherogenesis and an increased risk of atherothrombotic complications. Multiple mechanisms contribute to the pro-thrombotic status which characterizes DM patients underscoring the importance of antiplatelet therapies used for secondary prevention in these patients. For many years, dual antiplatelet therapy (DAPT) with aspirin and the P2Y₁₂ inhibitor clopidogrel has represented the mainstay of treatment following an acute coronary syndrome (ACS) or in patients undergoing percutaneous coronary interventions (PCI). Although DAPT reduces the incidence of atherothrombotic recurrences, these rates remain high in DM patients underscoring the need for more efficacious therapies. Oral platelet P2Y₁₂ receptor inhibitors with enhanced potency, such as prasugrel and ticagrelor, as well as antiplatelet therapies such as vorapaxar inhibiting the thrombin-mediated platelet signaling pathway, constitute treatment opportunities for patients with DM and have shown to be associated with a greater reduction in ischemic recurrences, albeit at the cost of more bleeding. This article reviews currently available antiplatelet agents and delivers an update on the advances and drawbacks of these agents used for secondary prevention in DM patients experiencing an ACS or undergoing PCI.

Adverse clinical outcomes associated with double dose clopidogrel compared to the other antiplatelet regimens in patients with coronary artery disease: a systematic review and meta-analysis

BACKGROUND

Recently, several newer antiplatelet treatment strategies have been used in patients with coronary artery disease (CAD). Apart from the dual antiplatelet therapy (DAPT) consisting of aspirin and clopidogrel, double dose clopidogrel (DDC), triple antiplatelet therapy (TAPT) consisting of aspirin, clopidogrel and cilostazol and other newer antiplatelet agents have shown to be effective in different ways. In this analysis, we aimed to systematically compare the adverse clinical outcomes and the bleeding events which were observed when DDC was compared to the other antiplatelet regimens in patients with CAD.

METHODS

English publications comparing DDC with other antiplatelet regimens were searched from MEDLARS/MEDLINE, EMBASE, www.ClinicalTrials.gov and Google Scholar. Adverse cardiovascular outcomes and bleeding events were the study endpoints. Statistical analysis was carried out by the RevMan 5.3 software whereby odds ratios (OR) with 95% confidence intervals (CIs) were calculated.

RESULTS

A total number of 23,065 participants were included. Results of this analysis showed major adverse cardiac events (MACEs), all-cause mortality, cardiac death, stroke, stent thrombosis, revascularization and myocardial infarction (MI) to have been similarly manifested in patients who were treated with DDC versus the control group with OR: 0.98, 95% CI: 0.78-1.22; p = 0.83, OR: 0.95, 95% CI: 0.77-1.17; p = 0.62, OR: 0.97, 95% CI: 0.79-1.20; p = 0.81, OR: 0.98, 95% CI: 0.65-1.48; p = 0.94, OR: 0.84, 95% CI: 0.40-1.75; p = 0.64, OR: 0.88, 95% CI: 0.52-1.49; p = 0.63, and OR: 0.89, 95% CI: 0.65-1.21; p = 0.45 respectively. Any minor and major bleedings were also similarly manifested. When DDC was compared to DAPT, no significant difference was observed in any bleeding event with OR: 1.58, 95% CI: 0.86-2.91; p = 0.14. Even when DDC was compared with either ticagrelor or prasugrel or TAPT, still no significant difference was observed in terms of bleeding outcomes.

CONCLUSIONS

In patients with CAD, adverse clinical outcomes were not significantly different when DDC was compared to the other antiplatelet regimens. In addition, bleeding events were also similarly manifested when DDC was compared to DAPT, TAPT or ticagrelor/prasugrel.

Changes in platelet morphology indices in relation to duration of disease and glycemic control in children with type 1 diabetes mellitus

BACKGROUND

There is limited data on platelet alterations in children with type 1 diabetes mellitus (T1DM). We planned to study the effect of glycemic control and duration of T1DM on platelet morphology in children with T1DM.

METHODS

We conducted an observational study on 260 children; 130 with T1DM (cases) and 130 healthy controls, in a tertiary care pediatric hospital. Platelet indices including Platelet count (PLT), Mean Platelet Volume (MPV), Platelet Distribution Width (PDW), Platelet-Large cell ratio (P-LCR), Plateletcrit (PCT) were measured, and their means were compared between cases and controls and various subgroups among the cases.

RESULTS

The MPV, PDW and P-LCR were significantly higher (p < 0.05) in cases when compared to controls and in children with suboptimal glycemic control compared to optimal control. PLT was considerably lower in cases compared to controls. In children with new-onset T1DM, only PDW was significantly raised when compared to controls. MPV and P-LCR had a significant positive correlation with duration of T1DM.

CONCLUSIONS

Children with T1DM have altered morphological parameter(s) which progress over time. Poor glycemic control is a significant risk factor for abnormal platelet indices.

Efficacy of 2.5-mg Prasugrel in Elderly or Low-Body-Weight Patients

BACKGROUND

Due to concern about bleeding complications, a maintenance dose of prasugrel 2.5 mg may be used in elderly or low-body-weight patients in Japan. There is little information, however, on the efficacy and safety of a 2.5-mg maintenance dose of prasugrel.

METHODS AND RESULTS

In this single-center, prospective, open-label, cross-over study, a total of 44 elderly (≥75 years old) or low body-weight (<50 kg) Japanese patients >1 month after percutaneous coronary intervention who were treated with aspirin 81-100 mg and clopidogrel 75 mg were randomized to either prasugrel 2.5 mg or 3.75 mg instead of clopidogrel for 14 days, with a cross-over directly to the alternate treatment for another 14 days. Platelet inhibition was assessed with the VerifyNow assay (Accumetrics, San Diego, CA, USA) at 3 time points: baseline; day 14; and day 28. P2Y12 reaction units (PRU) ≤95 was defined as low on-treatment platelet reactivity (LPR), and PRU ≥262 as high on-treatment platelet reactivity (HPR). The prevalence of LPR was 2.2% in patients treated with clopidogrel, 2.2% in those with prasugrel 2.5 mg, and 22.7% in those with prasugrel 3.75 mg (P<0.001). Clopidogrel resulted in the higher prevalence of HPR compared with 2.5-mg and 3.75-mg prasugrel (40.9% vs. 18.2% vs. 6.8%, P<0.001).

CONCLUSIONS

Prasugrel 2.5 mg may be more appropriate in elderly or lower-body-weight Japanese patients.

Differential impact of diabetes mellitus on antiplatelet effects of prasugrel and clopidogrel

Background

Although prasugrel exerts stronger antiplatelet effects compared with clopidogrel, the factors affecting platelet reactivity under prasugrel have not been fully determined. This study aimed to find the novel mechanistic differences between two thienopyridines and identify the factor that influence platelet reactivity to each drug.

Methods

Forty patients with stable angina who underwent elective percutaneous coronary intervention were randomly assigned to receive either prasugrel (20 mg) or clopidogrel (300 mg) as a loading dose. Platelet function (light transmission, laser light scattering, and vasodilator-stimulated phosphoprotein phosphorylation) and plasma active metabolite levels were measured after the loading dose.

Results

Prasugrel consistently inhibited adenosine diphosphate receptor P2Y₁₂ signalling to abolish amplification of platelet aggregation. Prasugrel abolished even small platelet aggregates composed of less than 100 platelets. On the other hand, clopidogrel inhibited large aggregates but increased small and medium platelet aggregates. Diabetes was the only independent variable for determining antiplatelet effects and active metabolite concentration of prasugrel, but not clopidogrel. Sleep-disordered breathing was significantly correlated with platelet reactivity in patients who had clopidogrel.

Conclusions

Prasugrel efficiently abolishes residual P2Y₁₂ signalling that causes small platelet aggregates, but these small aggregates are not inhibited by clopidogrel. Considering the differential effect of diabetes on antiplatelet effects between these two drugs, the pharmacokinetics of prasugrel, other than cytochrome P450 metabolism, might be affected by diabetes.

Trial registration

UMIN-CTR UMIN000017624, retrospectively registered 21 May 2015.

Modifying Effect of Diabetes on the Short-term Effect of Clopidogrel in Patients with Myocardial Infarction

Background:

Patients with diabetes are reported having inadequate response to clopidogrel treatment compared with patients without diabetes. The present study aims to investigate the effect of clopidogrel treatment in lowering in-hospital major adverse cardiovascular events (MACEs) among hospitalized myocardial infarction (MI) patients with and without diabetes.

Materials and Methods:

This is a post hoc analysis of the third phase of Clinical Pathways in Acute Coronary Syndromes program study. Between October 2011 and November 2014, a total of 14,997 patients with MI were consecutively recruited from 101 county hospitals without the capacity to perform onsite percutaneous coronary intervention (PCI).

Results:

The mean age of the 14,997 patients with MI was 64.8 ± 12.2 years, and 67.5% of the participants were male. Of these patients, 1920 (12.8%) were classified as diabetes when presenting at the hospital, and 12,875 (85.9%) patients received in-hospital clopidogrel treatment. In total, 167 patients (8.7%) with and 955 patients (7.3%) without diabetes experienced an in-hospital MACE. Multivariable-adjusted relative risk (RR) associated with clopidogrel treatment for in-hospital MACEs was 0.79 (95% confidence interval [CI]: 0.68–0.93) among all MI patients, and it was also consistent between patients with (RR = 0.79, 95% CI: 0.54–1.16) and without diabetes (RR = 0.79, 95% CI: 0.65–0.95; P for interaction = 0.970). Propensity score-matched subgroup analyses yielded similar results.

Conclusion:

Our large-scale study of real-world data from non-PCI-capable hospitals in China demonstrated that clopidogrel treatment was associated with a lower risk of in-hospital MACEs in MI patients, and this effect was not modified by diabetes.

The Evolving Concept of Dual Antiplatelet Therapy after Percutaneous Coronary Intervention: Focus on Unique Feature of East Asian and "Asian Paradox"

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor is essential after percutaneous coronary intervention (PCI), while many studies have focused on determining the optimal degree of platelet inhibition and optimal DAPT duration to minimize complications after PCI. Current guidelines developed by the American College of Cardiology/American Heart Association and the European Society of Cardiology summarize previous studies and provide recommendations. However, these guidelines are mainly based on Western patients, and their characteristics might differ from those of East Asian patients. Previous data suggested that East Asian patients have unique features with regard to the response to antiplatelet agents. On comparing Western and East Asian patients, it was found that East Asian patients have a lower rate of ischemic events and higher rate of bleeding events after PCI, despite a higher on-treatment platelet reactivity, which is referred to as the “East Asian paradox.” As the main purpose of DAPT is to minimize ischemic and bleeding complications after PCI, these differences should be clarified before adopting the guidelines for East Asian patients. Therefore, in this article, we will review various issues regarding DAPT in East Asian patients, with a focus on the unique characteristics of East Asian patients, previous studies regarding antiplatelet agents in East Asian patients, and a guideline from an East Asian perspective.

Impact of acute exacerbations on platelet reactivity in chronic obstructive pulmonary disease patients

Background

A higher risk of atherothrombotic cardiovascular events, which are platelet-driven processes, has been described during acute exacerbations of chronic obstructive pulmonary disease (AECOPD). However, the relevance of platelet reactivity during AECOPD and whether this is affected by antiplatelet agents are not fully elucidated to date. This study aimed to evaluate whether platelet reactivity is augmented during an exacerbation in COPD patients with and without antiplatelet therapy and its association with systemic inflammatory parameters.

Materials and methods

Prospective, observational, ex vivo investigation was conducted in consecutive patients suffering an exacerbation of COPD. Platelet reactivity was assessed during AECOPD and at stable state. Platelet function assays included: 1) vasodilator-stimulated phosphoprotein assay expressed as P2Y₁₂ reactivity index (PRI), 2) multiple electrode aggregometry and 3) optical aggregometry. Systemic inflammatory parameters such as leukocyte count, interleukin-6 and fibrinogen were also assessed.

Results

Higher platelet reactivity was observed during AECOPD compared to stability measured by vasodilator-stimulated phosphoprotein (PRI: 75.2%±1.9% vs 68.8%±2.4%, p=0.001). This augmented platelet aggregability was also observed in the subset of patients on antiplatelet therapy (PRI: 72.8%±3.1% vs 61.7%±7.5%, p=0.071). Consistent findings were observed with all other platelet function tests. Patients with greater enhancement of inflammatory markers during AECOPD were more likely to present a higher increase in platelet reactivity.

Conclusion

Platelet reactivity is increased during AECOPD, which may contribute to the augmented cardiovascular risk of these patients. Additionally, the increase in platelet reactivity might be associated with an increment in inflammatory markers during exacerbations.

[Coronary thrombosis: Physiopathology and treatment in the era of tailored medicine]

Coronary thrombosis remains the leading cause for cardiovascular death in France. Great advances have been made in the knowledge of the basic mechanism involved in coronary thrombogenesis and in antithrombotic treatments. They have led to substantial survival benefit after myocardial infarction and enabled development of tailored therapeutic strategies, especially for high-risk patients. Direct oral anticoagulants have now entered the game for secondary prevention after coronary thrombosis.

Identification of poor response to P2Y12 inhibitors in ACS patients with a new ELISA-based vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation assay

A new ELISA technique has been developed to measure the vasodilator-associated stimulated phosphoprotein (VASP) platelet reactivity index (PRI) in clopidogrel-treated patients. This technique has not been evaluated in acute coronary syndrome (ACS) patients or in prasugrel-treated patients. We assessed the accuracy of ELISA-VASP to identify high on-treatment platelet reactivity (HPR) in ACS patients in comparison with established platelet function tests. Platelet reactivity was measured in 240 ACS patients treated with clopidogrel (75 or 150 mg) or prasugrel (5 or 10 mg) using flow cytometry (FC-VASP) and the ELISA-VASP technique, light transmission aggregometry (LTA) and VerifyNow-P2Y12 assay (VN-P2Y12). When using the ELISA-VASP PRI, the rate of patients with HPR in the overall ACS population was 15.5%, including a 27% rate in clopidogrel-treated patients and a 4% rate in prasugrel-treated patients. There was a strong correlation between ELISA-VASP PRI and FC-VASP PRI (r = 0.83, r2 = 0.68 p < 0.0001) with an area under the receiver-operating characteristics (ROC) curve to identify HPR (VASP-PRI >50% with FC-VASP) of 0.94, p<0.0001. The threshold of 60% for ELISA-VASP PRI provided the best accuracy (likelihood ratio= 23.67) to identify patients with HPR when compared to FC-VASP, LTA or VN-P2Y12 assays. In conclusion, ELISA-VASP is a fast, easy-to-use and specific test to identify HPR in ACS patients on thienopyridines. A 60% threshold value displays the best accuracy to identify HPR in these patients.

Decrease in high on-treatment platelet reactivity (HPR) prevalence on switching from clopidogrel to prasugrel: Insights from the switching anti-platelet (SWAP) study

The prevalence of high platelet reactivity (HPR) in patients who have switched from clopidogrel to prasugrel during maintenance phase after an acute coronary syndrome (ACS) event is unknown. Therefore, the effect of switching from clopidogrel to prasugrel on the prevalence of HPR was evaluated. This analysis from the previously reported SWAP (SWitching Anti Platelet) study assessed HPR at baseline, 2 and 24 hours, and seven days after switching from clopidogrel to prasugrel maintenance dose (MD), with or without a prasugrel loading dose (LD) using four definitions: maximum platelet aggregation (MPA) >65% (primary endpoint), MPA >50%, P2Y12 reaction units (PRU) >235, and platelet reactivity index (PRI) ≥50%. A total of 95 patients were available for analysis; 56 patients provided DNA for genetic assessments of cytochrome P450 (CYP) 2C19. There were 26 (27.4%) patients with HPR at the end of the clopidogrel run-in (defined as MPA >65%). The HPR prevalence varied by each definition and ranged from 19% (PRU >235) to 68% (PRI ≥50%). A significantly higher HPR prevalence was observed during clopidogrel versus the combined prasugrel therapy groups at seven days as measured by MPA >65% (21.2% vs. 4.5%, p>0.05), PRU >235 (18.8% vs. 0%, p=0.001), and PRI ≥50% (66.7% vs. 7.9%, p<0.0001). There was a significantly higher percentage of subjects carrying at least one reduced function allele with HPR measured by MPA >65% (p=0.02) or PRU >235 (p=0.05) than non-carriers with HPR. Switching ACS patients during maintenance clopidogrel therapy to prasugrel with or without an LD is associated with a reduced HPR prevalence and may provide an alternative strategy to treat patients with HPR, independent of CYP2C19 genotype.

Platelet function profiles in the elderly: Results of a pharmacodynamic study in patients on clopidogrel therapy and effects of switching to prasugrel 5 mg in patients with high platelet reactivity

Studies specifically designed to assess clopidogrel response in the elderly as well as treatment alternatives to improve platelet inhibition in this highrisk population are lacking. This study aimed to define phar-macodynamic (PD) profiles, including high platelet reactivity (HPR) rates, among elderly patients on maintenance clopidogrel therapy and to assess the PD effects of prasugrel 5 mg/day in elderly with HPR. This was a prospective observational PD study enrolling consecutive ≥75-year-old patients on maintenance clopidogrel therapy (75 mg/day) who were tested for clopidogrel response by the VerifyNow P2Y12 assay and light transmittance aggregometry (LTA). HPR rates were estimated using multiple definitions. HPR patients identified by the VerifyNow P2Y12 assay [P2Y12 reaction unit (PRU) ≥230] were switched to prasugrel 5 mg/day, and platelet function testing was performed after 15 days of treatment. PD testing was completed in 100 patients. The HPR prevalence varied between 25% and 32%, depending on the definition used. A PRU ≥230 was observed in 25 patients; of these, 20 switched to prasugrel 5 mg/day. This resulted in significant reduction in PRU mean values (279.8 ± 45.1 vs. 171.7 ± 65.2, p=0.0002) with an absolute between-treatment difference of 108.1 (95% confidence intervals 75.2–140.9). Accordingly, switching to prasugrel 5 mg/day overcame HPR in most (80%) patients. Consistently, all LTA measures were significantly lower after prasugrel compared with clopidogrel. In conclusion, a considerable proportion of elderly patients exhibit HPR while on standard clopidogrel therapy. Switching to 5 mg/day prasugrel in elderly patients with HPR is associated with enhanced platelet inhibition and overcomes HPR in the majority of these patients.

Early determination of clopidogrel responsiveness by platelet reactivity index identifies patients at risk for cardiovascular events after myocardial infarction

While acute myocardial infarction (MI) is associated with impaired clopidogrel responsiveness, systematic evaluation is lacking due to the inability of functional aggregation-based assays to analyse clopidogrel responsiveness in the presence of glycoprotein IIb/IIIa inhibitors. Using the P2Y12-specific, non-aggregation-based platelet-reactivity-index (PRI) we assessed clopidogrel responsiveness in patients with acute MI. Clopidogrel responsiveness was determined 24 hours (h) after loading with 600 mg clopidogrel in 54 patients with acute MI admitted for coronary intervention. A PRI > 50% was considered as suboptimal inhibition. Overall response in MI patients was suboptimal with a median PRI of 58%. Diabetes, low high-density lipoprotein and pre-hospital clopidogrel loading were associated with impaired clopidogrel responsiveness. Patients loaded at first medical contact had a significantly weaker platelet inhibition by clopidogrel after 24 h (PRI 63%) compared to those loaded peri-interventionally (PRI 54%, p=0.014). Clinical outcome was assessed as a combination of cardiac death, non-fatal MI, stent thrombosis, ischaemic stroke, and urgent target vessel revascularisation after 12 months. The pre-selected cut-off of PRI ≤ 50% yielded a sensitivity of 87% at a specificity of 26%, whereas a PRI ≤ 57% determined by receiver-operating characteristics (ROC)-analysis yielded a sensitivity of 80% at a specificity of 56% (event rate: PRI ≤ 57%: 12.0%; PRI > 57%: 41.4%, p=0.0136). In conclusion, PRI detects clopidogrel responsiveness in acute MI patients requiring glycoprotein IIb/IIIa antagonism; and impaired clopidogrel responsiveness predisposes to clinical events. Pre-hospital clopidogrel loading was associated with impaired response and more adverse events challenging the concept of earliest oral clopidogrel loading in MI patients.

Prevalence of poor biological response to clopidogrel

The existence of poor biological response to clopidogrel has been shown in some patients. Despite the increasing number of studies, this phenomenon remains difficult to quantify. We performed a systematic review to estimate the prevalence of poor biological response to clopidogrel and investigate the factors known to modulate this. An exhaustive search was performed. Altogether 171 publications were identified, providing data for a total of 45,664 subjects. The estimated prevalence of poor biological response to clopidogrel ranged from 15.9% to 49.5% according to the platelet function assay employed. The assays most frequently used were light transmittance aggregometry (LTA), the vasodilator-stimulated phosphoprotein (VASP) assay and the Verify -now® assay. For all these assays, higher cut-off values were associated with a lower prevalence of poor biological response to clopidogrel. However, when choosing a fixed cut-off point for each assay, the prevalence of poor biological response to clopidogrel was highly variable suggesting that other factors could modulate poor biological response to clopidogrel. Finally, none of the studied factors could apparently explain the variability of poor biological response to clopidogrel. This meta-analysis shows that the prevalence of poor biological response depends on the assay employed, the cut-off value and on various unidentified additional factors.

Thrombosis in diabetes: a shear flow effect?

Cardiovascular events are the major cause of morbidity and mortality in Type 2 diabetes (T2D). This condition is associated with heightened platelet reactivity, contributing to increased atherothrombotic risk. Indeed, individuals with diabetes respond inadequately to standard antiplatelet therapy. Furthermore, they often experience recurrent events as well as side effects that include excess bleeding. This highlights the need for identification of novel regulators of diabetes-associated thrombosis to target for therapeutic intervention. It is well established that platelet aggregation, a process essential for thrombus formation, is tightly regulated by shear stress; however, the mechanisms underlying shear activation of platelets, particularly in the setting of diabetes, are still poorly understood. This review will address the limitations of current diagnostic systems to assess the importance of shear stress in the regulation of thrombus formation in T2D, and the inability to recapitulate the pro-thrombotic phenotype seen clinically in the setting of T2D. Moreover, we will discuss recent findings utilizing new technologies to define the importance of shear stress in thrombus formation and their potential application to the setting of diabetes. Finally, we will discuss the potential of targeting shear-dependent mechanisms of thrombus formation as a novel therapeutic approach in the setting of T2D.

Association of CYP2C19*2 polymorphism with clopidogrel response and 1-year major adverse cardiovascular events in a multiethnic population with drug-eluting stents

BACKGROUND

Patients undergoing elective percutaneous coronary intervention (PCI) with drug-eluting stents (DES) who have impaired clopidogrel response, have a higher risk of subsequent major adverse cardiovascular events (MACE).

AIM OF THE STUDY

To establish the relationship between CYP2C19 genotype, clopidogrel responsiveness and 1-year MACE.

MATERIALS & METHODS

Aspirin/clopidogrel responses were assessed with Multiplate Analyzer and CYP2C19*2 allele by SpartanRx.

RESULTS

A total of 42.0% carried ≥1 CYP2C19*2 allele. Prevalences of aspirin and clopidogrel high on-treatment platelet reactivity (HPR; local cutoffs: 300 AU*min for aspirin and 600 AU*min for clopidogrel) were 11.5% and 19.8% respectively. In multivariate ana-lysis, clopidogrel HPR was found to be an independent predictor for 1-year MACE (adj HR: 3.48, p = 0.022 ).

CONCLUSION

Having clopidogrel HPR could be a potentially modifiable risk factor guided by phenotyping.

Sepsis favors high-on-clopidogrel platelet reactivity

High-on-treatment platelet reactivity (HPR) is associated with ischemic events in patients on antiplatelet therapy with a history of cardiovascular disease. On the other hand, recent data have associated sepsis with adverse cardiovascular events in patients admitted with bacteremia or respiratory infection. We aimed to assess P2Y₁₂-mediated platelet reactivity (PR) during sepsis and recovery in patients under clopidogrel. This was a prospective observational study. Incoming patients presenting with signs/symptoms of sepsis already on a maintenance dose of clopidogrel of 75 mg qd for cardiovascular events were included in this study. Patients were assessed for their PR on presentation and following septic syndrome, using the VerifyNow point-of-care P2Y₁₂ assay. Patients were excluded in the presence of evidence of noncompliance to antiplatelet regimen or in need of discontinuation during this study. Twenty-two septic patients on clopidogrel were included in this study (Supplemental Figure S1). Clopidogrel was administered for previous stroke, coronary, and peripheral artery disease in 27.3, 40.9, and 31.8% of patients, respectively. The main site of infection was respiratory tract followed by urinary tract, while the same amounts of gram-negative and -positive pathogens were isolated. HPR was noted in 77% and 29% of patients during sepsis and recovery, respectively, presenting a significant decrease in P2Y₁₂ reaction units values during follow-up [240.7 ± 58.3 versus 179.5 ± 58.4, 95% CI (-102.7, -39.76), p = 0.0002]. Five patients died of infection, while no adverse cardiovascular events were noted in our study. Our study shows that sepsis may favor HPR, which is reversed when recovery occurs. This finding may underlie the adverse cardiovascular events in patients admitted with sepsis, possibly requiring alteration of antiplatelet regimen during the inflammation period.

Use of Platelet Function Testing Before Pipeline Embolization Device Placement

Background and Purpose—

Thromboembolic complications constitute a significant source of morbidity after neurointerventional procedures. Flow diversion using the pipeline embolization device for the treatment of intracranial aneurysms necessitates the use of dual antiplatelet therapy to reduce this risk. The use of platelet function testing before pipeline embolization device placement remains controversial.

Methods—

A retrospective review of prospectively maintained databases at 3 academic institutions was performed from the years 2009 to 2016 to identify patients with intracranial aneurysms treated with pipeline embolization device placement. Clinical and radiographic data were analyzed with emphasis on thromboembolic complications and clopidogrel responsiveness.

Results—

A total of 402 patients underwent 414 pipeline embolization device procedures for the treatment of 465 intracranial aneurysms. Thromboembolic complications were encountered in 9.2% of procedures and were symptomatic in 5.6%. Clopidogrel nonresponders experienced a significantly higher rate of thromboembolic complications compared with clopidogrel responders (17.4% versus 5.6%). This risk was significantly lower in nonresponders who were switched to ticagrelor when compared with patients who remained on clopidogrel (2.7% versus 24.4%). In patients who remained on clopidogrel, the rate of thromboembolic complications was significantly lower in those who received a clopidogrel boost within 24 hours pre-procedure when compared with those who did not (9.8% versus 51.9%). There was no significant difference in the rate of hemorrhagic complications between groups.

Conclusions—

Clopidogrel nonresponders experienced a significantly higher rate of thromboembolic complications when compared with clopidogrel responders. However, this risk seems to be mitigated in nonresponders who were switched to ticagrelor or received a clopidogrel boost within 24 hours pre-procedure.

Administration of Ticagrelor and Double-Dose Clopidogrel Based on Platelet Reactivity Determined by VerifyNow-P2Y12 for Chinese Subjects After Elective PCI

Previous studies have identified high on treatment platelet reactivity (HTPR) as a potent factor predicting ischemic events for patients with coronary heart disease. We assessed the efficacy and safety of ticagrelor (90 mg twice-daily) and double-dose of clopidogrel (150 mg once-daily) among Chinese patients for elective percutaneous coronary intervention. We enrolled 40 patients with HTPR from among 317 patients with non-ST-segment elevation acute coronary syndromes after a successful elective percutaneous coronary intervention (PCI). Platelet reactivity was measured by VerifyNow P2Y12 assay. Platelet reactivity was significantly lower for both groups when compared with baseline platelet reactivity after medication adjustment (all P < 0.001). The mean platelet reactivity units (PRU) was significantly lower for the ticagrelor group compared with that of the clopidogrel group over time (all P < 0.001). The differences in the rate of sustained HTPR at different time points between the two groups were significant (2 hours: 0% versus 60%; 8 hours: 5.6% versus 50%; 24 hours: 5.9% versus 43.8%, all P < 0.05). Genetic variation of CYP2C19*2 had no impact on PRU means or rate of HTPR in the ticagrelor group (P > 0.05). During the 30-day follow-up, no MACE occurred in any patient, and the overall risk of bleeding showed no difference between the two groups (35% versus 21%, P = 0.48). Our results suggest that ticagrelor may achieve a more rapid and greater platelet inhibition than double-dose clopidogrel. Further studies are still needed to assess the differences in efficacy and safety between ticagrelor and double-dose clopidogrel administration for Chinese patients post elective PCI.