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Platelet functional activity was assessed in healthy volunteers (HV, n=92), patients with stable angina pectoris (SA, n=42) and acute coronary syndrome (ACS, n=73), treated with acetylsalicylic acid (ASA) + clopidogrel and ASA + ticagrelor, respectively. In all HV and patients we have compared parameters of platelet aggregation (maximum light transmission and velocity, Tmax and Vmax) and parameters, characterizing exposure of platelet activation markers, evaluated by flow cytometry. HV platelets were activated by 10 μM, 1 μM TRAP, and 20 μM, 5 μM, 2.5 μM ADP; patient platelets were activated by 10 μM TRAP and by 20 μM and 5 μM ADP. Strong and significant correlations between the aggregation and flow cytometry parameters (the r correlation coefficient from 0.4 up to >0.6) most frequently were registered in HV platelet during activation by 1 μM TRAP and in SA patients during platelet activation by 20 μM and 5 μM ADP. However, in many other cases these correlations were rather weak (r < 0.3) and sometimes statistically insignificant. In HV the differences in PAC-1 binding parameters between platelets activated by 10 μM TRAP (the strongest agonist) and all ADP concentrations were negligible (≤ 10%), while CD62P binding (at all ADP concentrations) and LTA parameters for (5 μM and 2.5 μM ADP) were significantly lower (by 40-60%). Antiplatelet therapy in patients decreased all parameters as compared to HV, but to varying extents. For 10 μM TRAP the MFI index for PAC-1 binding (40-50% decrease) and for both ADP concentrations the Tmax values (60-85% decrease) appeared to be the most sensitive in comparison with the other parameters that decreased to a lesser extent. The data obtained indicate a possibility of inconsistency between different LTA and flow cytometry parameters in assessing platelet activity and efficacy of antiplatelet drugs.

Background: No study has so far evaluated the impact of chronic kidney disease (CKD) on high-on treatment platelet reactivity (HRPR) with ticagrelor and their prognostic consequences, that were therefore the aim of the present study., Methods: Patients on dual antiplatelet therapy with ASA+ticagrelor (90mg/twice a day) after percutaneous coronary revascularization for ACS were scheduled for platelet function assessment 30-90 days post-discharge. The primary study endpoint was defined as the occurrence of major cardiovascular events (a composite of cardiovascular death, recurrent acute coronary syndrome (MI), target vessel revascularization) at the longest available follow-up., Results: We included 396 patients, that were divided according to CKD (eGFR

Purpose: Clopidogrel resistance (CR) is mostly caused by interindividual variability of the platelet inhibition of clopidogrel, which may induce cardiovascular events. The aim of this research was to evaluate whether DNAm levels of CREB5 (cg01534253) are involved in CR among acute coronary syndrome (ACS) patients treated with clopidogrel., Methods: 72 patients(36 CR and 36 non-CR) who underwent ACS were included in this study. The VerifyNow P2Y12 assay was selected to evaluate residual platelet reactivity, and bisulfite pyrosequencing methods was used to examine DNA methylation levels on cg01534253. Secondly, CREB5 mRNA expression was analyzed via quantitative real-time PCR. Last, we employed logistic regression to test the interaction between genetic factors of CREB5 methylation and multiple clinical variables in CR patients., Results: Subunit analysis indicated that for patients whose HbA1c levels were ≥6.5% or whose GLU levels were ≥7 mmol/L, lower methylation of cg01534253 indicated a poorer clopidogrel response. In addition, CREB5 mRNA expression was increased in CR patients with GLU levels ≥7 mmol/L. Moreover, regression analysis indicated that the values of albumin and uric acid were correlated with the incidence of CR., Conclusions: Our findings were likely to provide fresh understanding for the new mechanism of platelet inhibition failure and promote individualized antiplatelet therapy., (© 2022 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

The most effective antiplatelet treatments for acute coronary syndrome (ACS) patients carrying CYP2C19 loss-of-function (LoF) alleles undergoing percutaneous coronary intervention (PCI) is still debating and conflicting. It was aimed to compare the efficacy and safety endpoints for these patients treated with alternative P2Y12 receptor blockers (e.g. prasugrel or ticagrelor) against clopidogrel. Literature was searched in PubMed, Cochrane library, Synapse and 1000 Genomes databases following PRISMA guidelines for identifying relevant studies. Aggregated risk was estimated by RevMan software using either fixed/random-effects models where P values<0.05 (two-sided) were considered statistically significant. Nine studies comprising 16,132 ACS patients undergoing PCI were included in this analysis in which 2,746 and 2,640 patients were in the CYP2C19 LoF clopidogrel and alternatives treatment group, respectively. It was demonstrated that patients treated with prasugrel or ticagrelor significantly reduced the risk of MACEs (RR 0.58; 95% CI 0.45-0.76; P <0.0001) as compared to patients with clopidogrel where both groups carrying CYP2C19 LoF alleles. Subgroup analysis showed that prasugrel or ticagrelor significantly reduced the risk of cardiovascular death (RR 0.44; 95% CI: 0.25-0.74; P =0.002) and MI (RR 0.60; 95% CI: 0.44-0.81; P =0.0008) while other clinical outcomes were not found statistically significant between these two groups; stroke (RR 0.77; 95% CI: 0.43-1.38; P =0.39), stent thrombosis (RR 0.67; 95% CI: 0.38-1.18; P =0.17), unstable angina (RR 0.55; 95% CI: 0.13-2.33; P =0.42), revascularisation (RR 0.79; 95% CI: 0.28-2.24; P =0.66). Bleeding events were not found significantly different between these groups (RR 1.06; 95% CI: 0.88-1.28; P =0.55). Considering efficacy and safety, alternative antiplatelets (e.g. prasugrel or ticagrelor) may be regarded as better treatment option as compared to clopidogrel for ACS patients undergoing PCI.

Purpose: Hyperuricemia carries an increased risk of atherothrombotic events in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI). This may at least in part be due to inadequate P2Y12 inhibition. The aim of this study was to prospectively investigate the potential association between hyperuricemia and decreased platelet inhibition by P2Y12 antagonists., Methods: Levels of uric acid as well as on-treatment residual platelet reactivity in response to adenosine diphosphate (ADP) were assessed in 301 clopidogrel-treated patients undergoing elective angioplasty and stenting, and in 206 prasugrel- (n = 118) or ticagrelor-treated (n = 88) ACS patients following acute PCI. Cut-off values for high on-treatment residual ADP-inducible platelet reactivity (HRPR) were based on previous studies showing an association of test results with clinical outcomes., Results: Hyperuricemia was significantly associated with increased on-treatment residual ADP-inducible platelet reactivity in clopidogrel- and prasugrel-treated patients in univariate analyses and after adjustment for differences in patient characteristics by multivariate regression analyses. In contrast, ticagrelor-treated patients without and with hyperuricemia showed similar levels of on-treatment residual platelet reactivity to ADP. HRPR occurred more frequently in clopidogrel- and prasugrel-treated patients with hyperuricemia than in those with normal uric acid levels. In contrast, hyperuricemic patients receiving ticagrelor did not have a higher risk of HRPR compared with those with normal uric acid levels., Conclusion: Hyperuricemia is associated with decreased platelet inhibition by thienopyridines but a normal response to ticagrelor. It remains to be established if lowering uric acid increases the antiplatelet effects of clopidogrel and prasugrel in hyperuricemic patients with HRPR.

Antagonists of the Adenosine Diphosphate (ADP) receptor, P2Y12, may inhibit platelet aggregation as a result of stimulation with arachidonic acid (AA). The potent P2Y12 blocker, Ticagrelor has greater anti-platelet effects than Clopidogrel. We explored the effects of Ticagrelor versus Clopidogrel on mean maximum aggregation ratios (MAR%) in response to AA stimulation in patients receiving aspirin in conventional doses. A total of 613 acute coronary syndrome (ACS) patients were followed from October 2017 to October 2018. At the one- and six-month follow-up visit, mean AA-MAR% was lower in the Ticagrelor group when compared with the Clopidogrel group (28.9% vs 31.7%, 28.4% vs 31.0%, p<0.001 and p=0.001, respectively). BARC1-2 bleeding occurred with greater frequency with Ticagrelor than in patients treated with Clopidogrel (29.3% vs 9.5%, p<0.001; 23.5% vs 9.3%, p<0.001). Excessive platelet inhibition and decreased AA-MAR% were considered the main reasons for the severe subcutaneous/dermal bleeding in Ticagrelor treated patients.

Background: The comparative efficacy and safety of ticagrelor versus clopidogrel in older patients with myocardial infarction (MI) has received limited study., Methods: We performed an observational analysis of all patients ≥80 years (n=14 005) who were discharged alive with aspirin combined with either clopidogrel (60.2%) or ticagrelor (39.8%) after a MI between 2010 and 2017 registered in the national registry SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies). Inverse probability treatment weighting was used in Cox regression models to adjust for differences in demographics, in-hospital therapies, and medications. The primary ischemic outcome (death, MI, or stroke), and bleeding were obtained from national registries at 1 year. A sensitivity analysis in <80-year-old patients was performed., Results: In patients ≥80 years, the incidence of the primary ischemic outcome (hazard ratio [HR], 0.97 [95% CI, 0.88-1.06]) was similar for ticagrelor- and clopidogrel-treated patients. Ticagrelor was associated with a 17% and 48% higher risk of death (HR, 1.17 [95% CI, 1.03-1.32]) and bleeding (HR, 1.48 [95% CI, 1.25-1.76]), but a lower risk of MI (HR, 0.80 [95% CI, 0.70-0.92]) and stroke (HR, 0.72 [95% CI, 0.56-0.93]). In <80-year-old patients, the incidence of the primary ischemic outcome was 17% (HR, 0.83 [95% CI, 0.77-0.89]) lower with ticagrelor. Ticagrelor was associated with 15% (HR, 0.85 [95% CI, 0.76-0.96]) lower risk of death, 32% higher risk of bleeding (HR, 1.32 [95% CI, 1.18-1.47]), but lower risk of MI (HR, 0.82 [95% CI, 0.75-0.91]) and stroke (HR, 0.82 [95% CI, 0.69-0.98])., Conclusions: Ticagrelor use among elderly patients with MI was associated with higher risk of bleeding and death compared with clopidogrel. A randomized study of ticagrelor versus clopidogrel in the elderly is needed.

Clopidogrel therapy reduces the occurrence of major vascular events in acute coronary syndrome (ACS) patients, but treatment efficacy is variable. The present study aims to determine the mechanisms that underlie associations between certain miRNA polymorphisms and clinical outcomes of clopidogrel therapy. Our study focused on 9 miRNA single nucleotide polymorphisms in addition to CYP2C19*2 and CYP2C19*3 . We found that the miR-605 rs2043556 AG genotype significantly decreased the risk of acute myocardial infarction (odds ratio, OR = 0.13, 95%CI 0.02-0.96, P = .045) and that the rs2043556 GG genotype significantly decreased the risk of unstable angina (OR = 0.19, 95%CI 0.05-0.65, P = .008) in ACS patients receiving clopidogrel therapy for more than one year. Dual-luciferase analysis indicated that miR-605 significantly decreased the mRNA expression of CYP2B6 and P2RY12 ( P < .01). In cells treated with miR-605-A, the protein and mRNA expression of CYP2B6 and P2RY12 were significantly lower than that of cells treated with miR-605-G ( P < .05). The results demonstrate that miR-605 targets the mRNA of the CYP2B6 and P2RY12 genes, and that rs2043556 A/G polymorphisms in miR-605 modulate the mRNA and protein expression of CYP2B6 and P2RY12 differently, which may impact the effect of clopidogrel in ACS patients.

Objective: To evaluate the effect of individualized antiplatelet therapy based on CYP2C19 genotype and platelet function on the prognosis of patients after percutaneous coronary intervention (PCI) compared with conventional antiplatelet therapy., Patients and Methods: Patients diagnosed with acute coronary syndromes (ACS) in Shandong Provincial Qianfoshan Hospital from December 2014 to December 2017 were included in this prospective study and randomly divided into conventional (CA) and individualized antiplatelet therapy group (IA) at 1:1 ratio. Patients in the CA group received clopidogrel 75 mg once a day (QD). Group IA was divided into extensive, intermediate, and poor metabolizers according to the results of the CYP2C19 gene test. Three genotypes were given clopidogrel 75 mg QD, 75 mg twice daily (BID) and ticagrelor 90 mg BID respectively. After taking these medicines for a period of time, platelet function was monitored by thromboelastography (TEG) and MAADP values were recorded. MAADP indicates the adenosine diphosphate (ADP) induced platelet function that not inhibited by medicine. High platelet reactivity (HPR) was defined as MAADP > 47mm, indicating a high risk of thrombus, and MAADP ≤ 31 mm indicates a high risk of hemorrhage. For extensive metabolizers (EMs) and intermediate metabolizers (IMs) patients with HPR, the antiplatelet therapy would be changed by the clinician according to the patient's conditions. Major adverse cardiovascular events (MACE) and hemorrhage events were monitored during 1-year follow-up., Results: The patients with MAADP > 47 mm were 89 (28.6%) in the IA group. There were 50 EMs patients with MAADP > 47 mm (33.3%). Of which, there were 2 cases which changed the dosage of clopidogrel to 75 mg BID, 14 cases who changed clopidogrel to ticagrelor. There were 36 IMs patients with MAADP > 47 mm (30.8%). Of which, there were 19 cases who changed clopidogrel to ticagrelor. There was no significant difference in the value of MAADP between EMs and IMs patients. Within 1 year after PCI, the occurrence of MACE in the IA group was significantly lower than that in the CA group (p=0.010)., Conclusions: (1) Patients with a CYP2C19 loss-of-function (LOF) gene who take double doses of clopidogrel overcome the decreased efficacy of clopidogrel which partly due to CYP2C19 LOF gene, without increasing the risk of hemorrhage. (2) Individualized antiplatelet therapy based on CYP2C19 genotype and platelet function can significantly reduce the occurrence of MACE (mainly acute non-fatal myocardial infarction) after PCI without increasing the risk of moderate or severe hemorrhage.

Objective: To investigate the effects of clopidogrel resistence and CYP2C19 genotype on the clinical prognosis of acute coronary syndrome(ACS) patients undergoing percutaneous coronary intervention(PCI). Methods: This study was a retrospective cohort study. ACS patients who underwent PCI in Beijing Anzhen Hospital from October 2015 to January 2017 were recruited. The inhibition rate of adenosine diphosphate(ADP) was monitored by thromboelastography. All of these patients were divided into clopidogrel resistance and non-resistance group according to the monitoring results. CYP2C19 genotype was detected by TaqMan probe-based real-time quantitative PCR. Patients were divided into slow, medium and fast metabolic group, according to the CYP2C19 genotype. After 12 months of follow-up, the end points included all-cause death, cardiac death, angina, myocardial infarction, stent thrombosis, ischemic stroke and hemorrhage were collected. Combined thrombotic events were defined as a composite of angina, myocardial infarction, stent thrombosis and ischemic stroke. The differences of the incidence of clinical events between groups were compared. Cox regression was used to analyze the effects of clopidogrel resistance and CYP2C19 genotype on the combined thrombotic events, cardiac death and hemorrhage. Results: A total of 1 696 patients were included, and the age was (59.4±9.6) years, with 1 280(75.5%) males. There were 471 cases(27.8%) in clopidogrel resistance group, and 1 225 cases(72.2%) in clopidogrel non-resistance group. There were 218 patients(12.9%) were in slow metabolic group, 668(39.4%) in medium metabolic group, and 810 (47.8%) in fast metabolic group. The median follow-up time was 13.3 months, and 131 cases were lost to follow-up, with a loss follow-up rate of 7.7%. Compared with the clopidogrel non-resistance group, the clopidogrel resistance group had a higher incidence of myocardial infarction(7.6%(36/471) vs. 5.1%(62/1 225), P =0.041), a lower incidence of hemorrhage (13.2%(62/471) vs. 17.9%(219/1 225), P =0.020) and minor hemorrhage(11.5%(54/471) vs. 15.8% (194/1 225), P =0.022). There were no statistically significant difference in all-cause death, cardiac death, angina, stent thrombosis, ischemic stroke and severe bleeding between clopidogrel resistance and non-resistance group(all P >0.05). There was no statistically significant difference in the incidence of endpoint events among different CYP2C19 genotypes (all P >0.05). Cox regression analysis showed that clopidogrel resistance was an independent factor of combined thrombotic events ( OR =2.334, 95% CI 1.215-4.443, P =0.016) and bleeding events ( OR =0.481, 95% CI 0.174-0.901, P =0.023). While CYP2C19 genotype was not independent factor for combined thrombotic events, cardiac death and hemorrhage (all P >0.05). Conclusion: For ACS patients after PCI, clopidogrel resistance can increase the risk of combined thrombotic events, but also reduce the risk of bleeding; while CYP2C19 genotype is not an independent factor for clinical prognosis.

Background: Acute coronary syndrome (ACS) is a highly thrombotic state, and a sustained antiplatelet effect is vital to the prevention of thrombotic complications. Clopidogrel, the most widely used oral P2Y12 receptor antagonist in ACS, has attracted considerable attention because of significant variability in antiplatelet effect depending on the presence of CYP2C19 allele. Other P2Y12 receptor antagonists offer sustained and more predictable antiplatelet effects than clopidogrel albeit at an increased cost. Several studies have demonstrated the promising application of pharmacogenetics in choosing personalized antiplatelet therapy using the point-of-care genotype assays., Areas of Uncertainty: Guidelines regarding the genotype-guided approach to the selection of antiplatelet therapy have been conflicting, and studies evaluating the effect of pharmacogenetic-guided selection of antiplatelet therapy on the outcomes have demonstrated mixed results., Data Sources: A literature search was conducted using MEDLINE and EMBASE for studies reporting the association of pharmacogenetic-guided selection of antiplatelet therapy and the outcomes in patients with ACS until December 2018., Results: Presence of specific CYP2C19 allele significantly influences clopidogrel metabolism and associated outcomes in patients with ACS. Thrombotic and bleeding complications are more common in patients with loss-of-function (LOF) and gain-of-function (GOF) alleles, respectively. Although the pharmacogenetic-guided approach to the selection of antiplatelet therapy appears promising in ACS, studies have shown conflicting results, and direct randomized evidence linking this approach with the better outcomes is lacking., Conclusions: Genotype-guided selection of antiplatelet therapy is expected to be useful in patients undergoing percutaneous coronary intervention (PCI) with a high risk of adverse outcomes. The patient-physician discussion should be an essential part of this decision-making process. Large-scale multicenter randomized controlled trials using the point-of-care genotype assay are needed to investigate this approach further before its use can be recommended in all comers.

Although thrombelastography (TEG) has been widely implemented in the clinical setting of endovascular intervention, consensus on the optimal parameter for defining high ischemic risk patients is lacking due to the limited data about the relationship between various TEG parameters and clinical outcomes. In this article, we report a post hoc analysis of a prospective, single-center cohort study, including 447 patients with acute coronary syndrome (ACS). Arachidonic acid (AA)- or adenosine diphosphate (ADP)-induced platelet-fibrin clot strength (MA AA or MA ADP ) was indicative of the net residual platelet reactivity after the treatment with aspirin or clopidogrel, respectively. AA% or ADP% was indices of the relative platelet inhibition rate on AA or ADP pathway. We found that each parameter alone was predictive of the risk of 6-month ischemic event, even after adjusting for confounding factors. However, the association between AA% and clinical outcome disappeared when further adjusted for MA AA . Likewise, inclusion of MA ADP changed the significant relation between ADP% and clinical outcome. MA ADP  > 47.0 mm and MA AA  > 15.1 mm were identified as the optimal cutoffs by receiver operating characteristic analysis. High MA AA (HR = 3.963; 95% CI: 1.152-13.632; P = 0.029) and high MA ADP (HR = 5.185; 95% CI: 2.228-12.062; P < 0.001) were independent predictors when both were included in multivariable Cox regression hazards model. Interestingly, an even higher risk was found for the coexisting high MA AA and high MA ADP (HR = 7.870; 95% CI: 3.462-17.899; P < 0.001). We conclude that when performing TEG to predict clinical efficacy, residual platelet reactivity has superiority over platelet inhibition rate as a measure of thrombotic risk in patients treated with aspirin and clopidogrel after ACS.

Backgrounds: Clopidogrel resistance (CR), which was manifested as the failure of platelet inhibition in clopidogrel treatment, was likely to lead to cardiovascular events. Our study was aimed to explore the contribution of DNA methylation in glucokinase (GCK) to the CR risk., Methods: Among 36 CR and 36 non-CR acute coronary syndrome (ACS) patients, the platelet functions were evaluated by VerifyNow P2Y12 assay (turbidimetric-based optical detection) and DNA methylation levels on two fragments of the CGI from the GCK were investigated through bisulfite pyrosequencing methods. In addition, the GCK mRNA expression was analyzed via quantitative real-time PCR. Lastly, the logistic regression was employed to test the interaction between GCK methylation and nongenetic variables in CR patients., Results: Subunit analysis showed that in male patients without DM but suffering from dyslipidemia, the increased methylation of cg18492943 indicated a risk of poor clopidogrel response (male, NCR vs CR(%): 84.86 ± 6.29 vs 88.16 ± 4.32, P = .032; without DM, NCR vs CR (%): 84.66 ± 6.18 vs 88.16 ± 4.17, P = .029; and dyslipidemia, NCR vs CR (%): 83.81 ± 6.96 vs 88.39 ± 4.74, P = .042).In addition, GCK mRNA expression was reduced in CR patients without DM. Moreover, regression analysis indicated that the values of platelet distribution width (PDW), total cholesterol (TC), and uric acid (UA) were correlated with the incidence of CR, and hypertension lowered the CR risk., Conclusions: A higher methylation of cg18492943 in GCK gene would lower the expression of GCK mRNA, which might contribute to CR in patients without DM. Meanwhile, PDW and TC might be risk factors in CR., (© 2019 The Authors. Journal of Clinical Laboratory Analysis Published by Wiley Periodicals, Inc.)

Objective: To evaluate the association of dual versus single antiplatelet therapy with major adverse cardiovascular events (MACE) in patients with acute coronary syndrome (ACS) in the Arabian Gulf., Subjects and Methods: Data were analyzed from 3,559 patients with a diagnosis of ACS admitted to 29 hospitals in 4 Arabian Gulf countries (Bahrain, Kuwait, Oman, and United Arab Emirates) from January 2012 to January 2013. Dual antiplatelet therapy (DAPT), consisting of aspirin and clopidogrel, was compared to aspirin alone. MACE included 12-months cumulative stroke/transient ischemic attack (TIA), myocardial infarction (MI), all-cause mortality, and readmissions for cardiac reasons, post discharge. Analyses were performed using multivariable logistic regression., Results: A total of 74% (n = 2,634) of the patients were on DAPT. At 12-month follow-up, patients on DAPT were significantly less likely to experience MACE events (adjusted OR [aOR] 0.73; 95% CI: 0.61-0.86; p < 0.001). Lower cardiovascular (CV) event rates were also consistent across the following MACE components; MI (aOR 0.66; 95% CI: 0.49-0.88; p = 0.005), all-cause mortality (aOR 0.69; 95% CI: 0.51-0.94; p = 0.018), and readmissions for cardiac reasons (aOR 0.79; 95% CI: 0.66-0.95; p = 0.011). Conversely, DAPT was adversely associated with increased risk of stroke/TIA (aOR 1.68; 95% CI: 1.05-2.69; p = 0.030)., Conclusions: DAPT, compared to aspirin therapy alone, was generally associated with better CV outcomes after an ACS event. However, DAPT was adversely associated with increased risk of stroke/TIA in ACS patients in the Arabian Gulf., (© 2019 The Author(s) Published by S. Karger AG, Basel.)

Microvesicles (MVs) released from leukocytes, platelets and endothelial cells are elevated in patients with acute coronary syndrome (ACS). In the present study, we assessed the potential pro-aggregatory properties of MVs obtained from ACS patients. Thus, we divided the patients into two groups based on clopidogrel-responsiveness, i.e. high on-treatment platelet reactivity (HPR; n  = 16), and low or normal on-treatment platelet reactivity (non-HPR; n  = 14), respectively. MVs from patients were obtained by high-speed centrifugation, and the pro-aggregatory effect of MVs added to fresh isolated platelets from healthy subjects were analyzed by 96-well microplate aggregometry. MVs from HPR patients significantly enhanced spontaneous platelet aggregation around two times more than MVs from non-HPR patients. The pro-aggregatory effect of three out of four MV phenotypes correlated to MV-concentrations as determined by flow cytometry. Furthermore, MVs from patients with diabetes mellitus ( n  = 9) had a stronger pro-aggregatory effect compared to MVs from those without diabetes ( n  = 21; p  = .025 between groups). In conclusion, MVs from ACS patients with clopidogrel non-responsiveness enhance platelet aggregation, as do MVs from ACS patients with diabetes. Thus, MVs from patients with hyperreactive platelets boost platelet aggregation. Blocking MV-formation may reduce platelet hyperreactivity.

Background The aim of this study was to evaluate the association of the carriage of the rs2244613 polymorphism of the CES1 gene with clopidogrel resistance as well as to evaluate the effectiveness of antiplatelet therapy in the carriers of this marker who have had acute coronary syndrome (ACS). This study also analyzes the procedure of percutaneous coronary intervention and compares the rs2244613 carrier rate between patients with ACS and healthy participants. Methods The study involved 81 patients diagnosed with ACS and 136 conditionally healthy participants. The optical detection of platelet agglutination by VerifyNow was employed to measure residual platelet reactivity in patients with ACS. The rs2244613 polymorphism was determined using real-time polymerase chain reaction. Results According to the results, the AA genotype of the rs2244613 polymorphism of the CES1 gene was detected in 37 patients (45.6%), the CA genotype in 42 patients (51.8%) and the CC genotype in 2 patients (2.6%). The level of residual platelet reactivity in rs2244613 carriers was higher compared with patients who did not have this allelic variant: 183.23 PRU ± 37.24 vs. 154.3 PRU ± 60.36 (p = 0.01). The frequencies of the minor allele C were 28.4% and 28.3% in patients with ACS and healthy participants, respectively. The results of the linear statistical model PRU due to CES1 genotype were as follows: df = 1, F = 6.96, p = 0.01). The standardized beta was 0.285 (p = 0.01) and R2 was 0.081. However, we also added CYP2C19*2 and *17 into the linear regression model. The results of the model were as follows: df = 3, F = 5.1, p = 0.003) and R2 was 0.166. Conclusions We identified a statistically significant correlation between the carriage of the rs2244613 polymorphism of the CES1 gene and the level of residual platelet aggregation among patients with ACS and the procedure of percutaneous coronary intervention.

The objective of this study was to determine the impact of polymorphism of CYP3A subfamily isoenzymes (allelic variants of CYP3A4*22 and CYP3A5*3) on the efficacy clopidogrel in patients with an acute coronary syndrome (ACS), who have undergone percutaneous coronary intervention (PCI). Platelet activity was determined on a VerifyNow P2Y12 test system in 81 patients with ACS aged 37-91 who had PCI. The activity of CYP3A4/5 was expressed as the ratio of the concentrations of cortisol and 6β-hydroxycortisol was performed by using high performance liquid chromatography. Genotyping was performed by using real-time polymerase real-time chain reaction. The frequencies for the CYP3A5 gene, rs 776746, were identified as follows: 77 (95.1%)-CC, 4 (4.9%)-CT; the allele frequencies by loci for the CYP3A4, rs rs35599367, were as follows: 78 (96.3%)-GG, 3 (3.7%)-AG. There was no statistically significant genotype-dependent difference between the presence of a minor T and G alleles and the presence of clopidogrel resistance (OR 3.53; 95% CI 0.46-26.94; p = 0.233 and p = 0.443, respectively). The average level of the metabolic relationship (6β-hydroxycortisol/cortisol) between the clopidogrel-resistant group and the normal platelet reactivity group was not statistically significantly different: 3.3 ± 2.8 versus 3.2 ± 3.2; p = 0.947. So, the activity of CYP3A4/5 was not related to platelet aggregation rates in this model. Genotyping and phenotyping CYP3A4\CYP3A5 does not predict the antiplatelet effect of clopidogrel. More extensive research is required to establish their clinical relevance.

Objective: To investigate the protective effect of ticagrelor on the myocardium of patients with ST-elevated acute coronary syndrome accompanied by diabetes mellitus., Patients and Methods: 210 patients with diabetes mellitus receiving emergency percutaneous coronary intervention (PCI) due to ST-elevated acute coronary syndrome from December 2014 to June 2018 in the Hospital were selected and randomly divided into ticagrelor group and clopidogrel group. The myocardial microcirculation perfusion was evaluated via ST-segment elevation resolution (STR) in electrocardiogram (ECG) and myocardial blush grade (MBG). Myocardial necrosis markers, including creatine kinase (CK), CK-MB, and cardiac troponin I (cTnI), were evaluated. Moreover, the cardiac function was assessed using brain natriuretic peptide (BNP) level and left ventricular ejection fraction (LVEF). Finally, patients were followed up for one month on average, and the adverse cardiovascular and bleeding events were recorded., Results: The results showed that CK, CK-MB, cTnI, and BNP levels in ticagrelor group were lower than those in clopidogrel group, and the differences were statistically significant (p<0.05). Thrombolysis in myocardial infarction (TIMI) flow grading after the operation had no statistically significant difference between the two groups, and the usage rate of tirofiban in ticagrelor group was lower than that in clopidogrel group (p<0.05). Besides, the myocardial microcirculation perfusion level after the operation in ticagrelor group was significantly higher than that in clopidogrel group. The proportions of STR ≥50% in ECG and MBG2 in ticagrelor group were significantly higher than those in clopidogrel group (p<0.01). The incidence rate of mild bleeding in ticagrelor group was higher than that in clopidogrel group (p<0.05)., Conclusions: The application of ticagrelor in the treatment of ST-elevated acute coronary syndrome accompanied by diabetes mellitus can increase the level of myocardial microcirculation perfusion and improve the left heart function.

CD34 + cells expressing KDR (CD34 + /KDR + ) represent a small proportion of circulating progenitor cells that have the capacity to interact with platelets and to differentiate into mature endothelial cells, thus contributing to vascular homeostasis and regeneration as well as to re-endothelialization. We investigated the levels of CD34 + and CD34 + /KDR + progenitor cells as well as their interaction with platelets in acute coronary syndrome (ACS) patients before the initiation (baseline) of their treatment with a P2Y 12 receptor antagonist, and at 5-days post-treatment (follow-up). Sixty-seven consecutive ACS patients and thirty healthy subjects (controls) participated in the study. On admission, all patients received 325 mg aspirin, followed by 100 mg/day and then were loaded either with 600 mg clopidogrel or 180 mg ticagrelor, followed by 75 mg/day (n = 36) or 90 mg × 2/day (n = 31), respectively. The levels of circulating CD34 + and CD34 + /KDR + progenitor cells, as well as their interaction with platelets, were determined by flow cytometry, before and after activation with ADP, in vitro. The circulating levels of CD34 + and CD34 + /KDR + cells in both patient groups at baseline were lower compared with controls while they were significantly increased at 5-days of follow-up in both groups, this increase being more pronounced in the ticagrelor group. The platelet/CD34 + (CD61 + /CD34 + ) conjugates were higher at baseline and reduced at follow-up while the platelet/KDR + (CD61 + /KDR + ) conjugates were lower at baseline and increased at follow-up, both changes being more pronounced in the ticagrelor group. ADP activation of control samples significantly increased the KDR expression by CD34 + cells and the CD61 + /KDR + conjugates, these parameters being unaffected in patients at baseline but increased at follow-up. Short-term dual antiplatelet therapy in ACS patients restores the low platelet/KDR + conjugates and CD34 + cell levels and improves the low membrane expression levels of KDR in these cells, an effect being more pronounced in ticagrelor-treated patients. This may represent a pleiotropic effect of antiplatelet therapy towards vascular endothelial regeneration.

Long-term evidence shows an increased risk of cardiovascular events in the morning hours and recent studies in aspirin-treated patients have shown increased platelet reactivity at the end of the dosing interval. Similar pharmacodynamic analyses of adenosine-diphosphate (ADP) receptor inhibitors are scarce. We therefore investigated changes in clopidogrel-dependent platelet function and activation over 24 h and whether enhanced platelet turnover might explain diurnal variability of platelet function and activation. Twenty-one patients after acute coronary syndromes (ACS) on maintenance doses of clopidogrel (75 mg) and aspirin (100 mg) Once per day (OD) were included. Blood was collected at five time points in 24 h. Platelet function and activation was analyzed by vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P), Verify Now, multiple electrode aggregometry (MEA), and platelet PAC-1 and P-selectin (P-sel) expression. Additionally, platelet count, mean platelet volume (MPV), and reticulated platelet fraction (RPF) were analyzed. There was significant diurnal variability of clopidogrel effects as documented with VASP-P, Verify Now, and PAC-1 and P-sel (all p < 0.05), whereas MEA did not differ over 24 h. Neither MPV nor RPF varied significantly over 24 h. In patients with high RPF, platelet function and activation was significantly higher in all assays, compared to patients with low RPF (all p < 0.05). However, the changes over time in low versus high RPF groups were similar. ADP-dependent platelet function and activation recovers significantly at the end of the 24-h dosing interval in patients with ACS on a maintenance dose of clopidogrel and aspirin. Although platelet function and activation is increased in patients with higher RPF, platelet turnover might not explain the observed diurnal variability.

Acute coronary syndrome (ACS) has become a vital disease with high mortality worldwide. A combined antiplatelet therapy (aspirin and a P2Y 12 antagonist) is commonly used to prevent re-infarction in ACS patients who have undergone percutaneous coronary intervention (PCI). Clopidogrel, a P2Y 12 antagonist, plays an important role in the inhibition of platelet aggregation (IPA). However, it is a pro-drug requiring biotransformation by cytochrome P450 (CYP450). The aim of this study is to unravel the effect of clopidogrel-associated genetic variants on inhibition of platelet activity and clinical outcomes in ACS patients. In our study, a total of 196 patients with metabolic gene polymorphism of clopidogrel were enrolled, and their antiplatelet effect as well as their cardiovascular events were collected. Approximately 2 mL of venous blood samples were used for genotype detection and another 4 mL were collected for platelet reactivity with thrombelastography. The primary clinical end-point was defined as a combination of cardiovascular mortality and revascularization for targeted vascular lesion. Based on the results of IPA, the prevalence of high on-treatment platelet reactivity (HPR) was 17.3% and the majority of patients (82.7%) obtained normal on-treatment platelet reactivity (NPR). The HPR group had significantly higher body mass index (BMI) and lower arachidonic acid (AA) induced IPA (P < 0.05). Therapy including Glycoprotein (GP) IIb/IIIa antagonist increased IPA (P < 0.05). ADP-induced IPA effect was lower with the presence of CYP2C19*2, *3 and paraoxonase (PON)1 Q192R loss-of-function (LOF) alleles, respectively (P < 0.05). Multivariate logistic regression analysis demonstrated that aspirin resistance (AA-induced IPA < 50%) had a greater risk of the occurrence of major adverse cardiovascular events (MACE) (OR = 3.817; 95% CI: 1.672-8.700; P = 0.002). CYP2C19*2 LOF alleles were associated with high risk of MACE in 1-year post PCI operations (OR = 2.571; 95% CI: 1.143-5.780; P = 0.030). For the ACS patients, the presence of CYP2C19*2 and PON1 Q192R LOF alleles were the major drivers of HPR., (© 2018 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y 12 inhibitor is a mainstay of the prevention of stent thrombosis following percutaneous coronary intervention (PCI). In the 2015 European guidelines for the management of acute coronary syndrome (ACS), prasugrel (PRA) and ticagrelor (TICA) combined with aspirin are recommended as first-line therapy. Clopidogrel (CLO) is recommended as an alternative medication for patients with contradictions to these new drugs. This single-center study analyzed the platelet function of 809 ACS patients undergoing PCI and treatment with DAPT. The platelet response to ADP was determined using Multiplate® analyzer at a median of 3 days after PCI in 254 patients treated with PRA (loading dose [LD] 60 mg, 10 mg qd), 162 patients receiving TICA (LD 180 mg, D 90 mg bid), and 393 CLO-treated patients (LD 600 mg, 75 mg qd). An aggregation >468 arbitrary units (AU)*min was defined as "high on-treatment platelet reactivity" (HPR), <188 AU*min as "low on-treatment platelet reactivity" (LPR). Platelet response in PRA-treated patients was lower compared to CLO or TICA (median; interquartile range: PRA 220 [163-275] AU*min vs. CLO 268 [186-387] AU*min, p < 0.001 vs. TICA 245 [190-320] AU*min, p = 0.001). Only 1.6% of PRA patients were stratified as HPR and 34.6% as LPR, while in the TICA group 1.9% fulfilled the criteria of HPR and 24.1% criteria of LPR. Sixteen percent of CLO patients were stratified as HPR and 26.2% as LPR. In a real-world cohort of ACS patients following PCI, PRA results in more potent inhibition of platelet function compared to CLO and TICA. TICA achieves a consistent antiplatelet effect with reduced rates of HPR and LPR in relation to CLO.

Present study was to evaluate whether switching ticagrelor to clopidogrel would impact platelet reactivity and cardiovascular outcomes in acute coronary syndrome (ACS) patients after percutaneous coronary intervention (PCI).A total of 202 ACS patients after PCI were enrolled and prescribed ticagrelor. Before discharge, 138 (68%) patients were switched to clopidogrel. Peripheral blood was obtained before switching and at 48 hours after switching to measure platelet reactivity. Patients were followed for 30 days to evaluate cardiovascular events.Compared to ticagrelor group, patients in clopidogrel group were more likely to be male (69.6% vs 65.6%), smokers (34.1% vs 31.3%) and had higher prevalence of hypertension (75.4% vs 71.9%). The frequency of right coronary artery lesion was significantly higher in ticagrelor group (34.4% vs 30.4%). There were no significant differences in baseline platelet reactivity (37.6 ± 5.2% vs 38.4 ± 4.9%). Forty-eight hours after switching to clopidogrel, platelet reactivity in clopidogrel group was significantly higher (46.3 ± 5.6% vs 38.1 ± 5.0%, P <.05). Patients in clopidogrel group had significantly higher incidence of cardiovascular events (3.6% vs 1.6%, P <.05). However, after further adjusted for platelet reactivity at 48 hours of switching, clopidogrel switching was not significantly associated with composite outcomes, with hazard ratio 1.08 (95% confidence interval 0.98-1.21, P = .063), indicating that platelet reactivity was a critical mediator between antiplatelet drug switching and cardiovascular outcomes.ACS patients after PCI treatment, early switching ticagrelor to clopidogrel results in increased platelet reactivity and higher incidence of short-term cardiovascular events.

Background: Prasugrel has been shown to provide more potency and less variability than clopidogrel, but its potential temporal variability has not been described.Methods and Results:We conducted a prospective open-label study, evaluating platelet reactivity overtime in acute coronary syndrome (ACS) patients on aspirin and clopidogrel (n=60) or prasugrel (n=61), after a percutaneous coronary intervention (PCI). Blood samples were taken at discharge and at 3 and 6 months. Platelet function tests included VerifyNow (VN-P2Y12), and Multiplate Aggregometry (MEA). By means of VN-P2Y12, prasugrel patients displayed significantly (P<0.001) higher platelet inhibition than clopidogrel patients over time, although there were not significant differences using MEA. Prasugrel patients showed higher platelet inhibition at baseline than at 3 months (59.3±8.1 vs. 105.0±49.2; P<0.001), without significant change at 6 months (107.9±72.0; P=0.919 vs. 3 months). Clopidogrel patients showed a similar trend (160.1±65.1, 184.8±62.7 and 185.0±53.3; baseline vs. 3 months P=0.060; 3 months vs. 6 months P=0.974). High platelet reactivity (HPR) was shown in 16.3% prasugrel patients, with no patient consistently remaining in HPR over time. HPR was detected in 36.6% of the clopidogrel patients, being consistently observed in 15.0% of them. Low platelet reactivity (LPR) was detected in 60.5% prasugrel and 9.8% clopidogrel patients., Conclusions: Prasugrel patients showed less temporal variation than patients on clopidogrel in terms of HPR. In contrast, higher variability in LPR was detected in prasugrel patients for up to 6 months' follow-up.

This review discusses the response variability to acetylsalicylic acid (ASA) and particularly to clopidogrel, and their relation to adverse recurrent ischaemic events in patients with arterial diseases. The higher rate of ASA resistance reported in the literature may be mainly due to the cyclooxygenase-1 non-specific assays, non-compliance, and underdosing. Clopidogrel response variability and non-responsiveness are established concepts. Moreover, high platelet reactivity (HPR) to adenosine diphosphate during clopidogrel therapy is now a known risk factor for recurrent ischaemic events in high-risk percutaneous coronary intervention/acute coronary syndrome patients. Variable active metabolite generation is the primary explanation for clopidogrel response variability and non-responsivenes. Variable levels of active metabolite generation following clopidogrel administration could be mainly explained by functional variability in hepatic cytochrome (CYP)P450 isoenzyme activity that is influenced by drug-drug interactions and single nucleotide polymorphisms of specific genes encoding CYP450 isoenzymes. Treatment with more potent P2Y12 receptor blockers, such as prasugrel and ticagrelor are credible alternative strategies to overcome HPR during clopidogrel therapy.

Carboxylesterase 1 (CES1) hydrolyzes the prodrug clopidogrel to an inactive carboxylic acid metabolite. The effects of CES1 S75N (rs2307240,C>T) on clopidogrel response among 851 acute coronary syndrome patients who came from the north, central and south of China were studied. The occurrence ratios of each endpoint in the CC group were significantly higher than in the CT + TT group for cerebrovascular events (14% vs 4.8%, p < 0.001, OR = 0.31), acute myocardial infarction (15.1% vs 6.1%, p < 0.001, OR = 0.37) and unstable angina (62.8% vs 37.7%, p < 0.001, OR = 0.36). The results showed that there was a significant association between CES1 S75N (rs2307240) and the outcome of clopidogrel therapy. Moreover, the frequency of the T allele of rs2307240 in acute coronary syndrome patients (MAF = 0.22) was more than four times higher than that in the general public (MAF = 0.05).

Objective To observe correlation between CYP2C19 *2/CYP2C19 *3 gene polymorphism with clopidogrel resistance and distribution of Chinese medicine ( CM) syndrome in acute coronary syndrome (ACS) population. Methods Peripheral blood was collected from 229 ACS patients from June 2014 to March 2015. DNAs were extracted, amplified, and sequenced. Correlations between CYP2C19 *2/CYP2Cl9 *3 gene polymorphisms and clopidogrel resistance/distribution of CM syndrome were analyzed. Gene frequency and allele frequency were tested using gene counting and one-sample K-S test. Correlation between gene types and distribution of CM syndrome was tested by Pearson corre- lation test. Results (1) The CYP2C19 *2 polymorphism distribution: CYP2C19 *2(A/A) (mutant homozygous) 12 cases (5. 2%) ; CYP2C19 * 2 ( G/A ) ( mutant heterozygote ) 93 cases (40. 6%), and CYP2C19 *2 (G/G) (normal homozygous) 124 cases (54. 2%). The mutant allele frequency was 0. 255. (2) The CYP2C19 *3 polymorphism distribution: CYP2C19 *3 (A/A) 0 case (0) ; CYP2C19 *3 (G/A) 26 cases (11. 4%), and CYP2C19 *3 (G/G) 203 cases (88. 6%). The mutant allele frequency was 0. 056. (3) Correlation between CYP2C19 gene polymorphism and clopidogrel resistance: Clopidogrel resistance was more liable to occur in mutant homozygous than in mutant heterozygote and normal homozygous (R =0. 30, P <0. 01). Clopidogrel resistance was more liable to occur in mutant heterozygote than in normal homozygous (R =0. 34, P <0. 01). (4) Among the 229 patients, the CM syndrome distribution were distributed as follows. Blockage of Xin vessels syndrome (BXVS, 33 cases, 14. 41%) ; qi deficiency blood stasis syndrome (QDBSS, 51 cases, 22. 27%) ; qi stagnation blood stasis syndrome (QSBSS, 92 cases, 40.18%) ; phlegm obstructing Xin vessel syndrome (POXVS, 17 cases, 7. 42%) ; yin-cold coag- ulation syndrome (YCCS, 8 cases, 3. 49%) ; qi-yin deficiency syndrome (QYDS, 13 cases, 5.68%) ; Xin-Shen yin deficiency syndrome (XSYDS, 5 cases, 2.18%), yang and qi deficiency syndrome (YQDS, 10 cases, 4. 37%). (5) CYP2C19 *2 gene type was significantly correlated with syndrome typing of CM (R =0. 26, P <0. 01). Mutant homozygous and most mutant heterozygote patients were syndrome typed as QDBSS. Conclusions The polymorphism of CYP2C19 was closely correlated with clopidogrel resist- ance in 229 ACS patients. Its occurrence rate was correlated with CYP2C19 *2/CYP2C19 *3 gene muta- tion frequency. Blood stasis syndrome ( QSBSS, QDBSS, BXVS) were main syndromes of ACS. Be- sides, QSBSS was obviously higher than the rest syndrome types. The polymorphism of CYP2C19 * 2 was correlated with syndrome typing of CM. CYP2C19 *2 gene defect mostly existed in QSBSS.