A study on platelet reactivity and associated clinical characteristics in acute coronary syndrome patients treated with Ticagrelor and Clopidogrel

Background: The pathophysiology of the acute coronary syndrome (ACS) is characterized by the rupture of an atherosclerotic plaque within the coronary artery, with subsequent platelet aggregation, thrombus formation, and ischemia. Before platelets aggregate, they must first be activated to express activated glycoprotein IIb/IIIa receptors on the cell surface. This activation is the result of stimulation from endogenous platelet agonists, such as thromboxane A2 and adenosine diphosphate (ADP). ADP activates platelets by binding to P2Y12 receptors on the cell surface. Despite clinical efficacy in a broad range of coronary artery disease patients, pharmacodynamic studies conducted in patients undergoing stenting showed that clopidogrel therapy was associated with variable and moderate platelet inhibition (50% inhibition at steady state as demonstrated by ex-vivo ADP-induced platelet aggregation) as well. Ticagrelor, a cyclopentyl-triazolo-pyrimidine acting as an analog of adenosine triphosphate (ATP), constitutes a first non-thienopyridine direct platelet P2Y12 receptor blocker. Aim of the study: To investigate factors linked to HOTPR on ticagrelor and whether they differ from factors linked to HOTPR on clopidogrel. Materials and methods: Totally 300 patients were included in the study Patients presenting to the Department of Cardiology, SRM Medical College Hospital and Research Institute, Kattangulathur, Veeraraghavan Sriram, Venkatesh Munusamy, Dhandapani Vellala Elumalai. A study on platelet reactivity and associated clinical characteristics in acute coronary syndrome patients treated with Ticagrelor and Clopidogrel. IAIM, 2019; 6(8): 26- 34. Page 27 Kanchipuram District, Chennai with an ACS between January 2018 to May 2019 were eligible for inclusion in the study if coronary angiography (±PCI) was planned and they were adequately pretreated with Ticagrelor or clopidogrel and aspirin. An ACS was defined as symptoms suggestive of myocardial ischemia lasting > 15 min with either troponin elevation or new electrocardiogram (ECG) changes consistent with myocardial ischemia. ECG changes consistent with myocardial ischemia included ≥ 1 mm of ST-segment deviation or T wave inversion ≥ 1 mm in at least 2 contiguous leads. Troponin was considered elevated if greater than 14 ng/L, with a rise and/or fall of 50% if 14-50 ng/L or 20% if >50 ng/L in a subsequent measure. Results: The mean age was 63 ± 12 years with 71.9% being male and 18% having diabetes. Patients predominantly presented with NSTEMI 76% and 24% as STEMI. Patients treated with Ticagrelor were younger, more likely to be male, less likely to present with STEMI, have suffered a previous MI, experience atrial fibrillation and be taking proton pump inhibitors or calcium channel blockers. Patients who were administered Ticagrelor demonstrated significantly lower platelet reactivity when stimulated with ADP compared to patients administered clopidogrel (30.3 AU vs 43.7 AU respectively, p<0.0001). Conclusion: This study demonstrates that Ticagrelor provides more potent platelet inhibition than clopidogrel measured by MEA. This is reflected in ticagrelor’s ability to reduce the proportion of ACS patients experiencing HOTPR. Different clinical factors contribute to HOTPR in ACS patients treated with Ticagrelor or clopidogrel. Clopidogrel dose, renal insufficiency, clinical presentation, and platelet count are linked to clopidogrel HOTPR. In contrast, only a history of myocardial infarction is associated with Ticagrelor HOTPR.

Effectiveness of Platelet Function Analyzer-100 for Laboratory Detection of Anti-Platelet Drug-Induced Platelet Dysfunction

BACKGROUND: High on-treatment platelet reactivity (HTPR) is the phenomenon wherein patients exhibit normal platelet activity in laboratory testing despite adequate adherence to anti-platelet treatment. We investigated the detection rates of Platelet Function Analyzer (PFA)-100 (Dade Behring AG, Düdingen, Switzerland) for drug-induced platelet dysfunction and analyzed potential contributors to HTPR with practical PFA-100 data over six years. METHODS: We used data from 6,957 patients who underwent PFA-100 testing after receiving aspirin, clopidogrel, or non-steroidal anti-inflammatory drugs (NSAIDs). Of these, 6,163 patients were tested with only the collagen/epinephrine cartridge (Col/EPI) of PFA-100; 794 were tested with both Col/EPI and the collagen/ADP cartridge (Col/ADP). We calculated PFA-100 closure time (CT) for each drug and compared the clinical and laboratory characteristics of the patients with prolonged CTs and normal CTs (i.e., HTPR). RESULTS: In Col/EPI, 73.2% (365/499), 72.6% (390/537), and 55.3% (3,442/6,228) patients showed prolonged CTs for aspirin, clopidogrel, and NSAIDs, respectively. In Col/ADP, prolonged CTs were observed in 37.4% (34/91), 43.2% (35/81), and 29.6% (200/676) of patients receiving aspirin, clopidogrel, and NSAIDs, respectively. Of the patients tested with both cartridges, 88.9% (48/54), 95.3% (41/43), and 89.0% (577/648) of the patients receiving aspirin, clopidogrel, and NSAIDs had prolonged CTs, and 10.0% (79/794) showed normal CTs regardless of drugs. For clopidogrel users (both cartridges), there were more patients with malignancies in the normal CT than prolonged CT group. CONCLUSIONS: PFA-100 is not sufficiently effective for laboratory screening of drug-induced platelet dysfunction. Malignancy may contribute to clopidogrel-related HTPR in PFA-100.

Clinical outcomes and predictive model of platelet reactivity to clopidogrel after acute ischemic vascular events / 中华医学杂志(英文版)

Background:@#High on-treatment platelet reactivity (HTPR) has been suggested as a risk factor for patients with ischemic vascular disease. We explored a predictive model of platelet reactivity to clopidogrel and the relationship with clinical outcomes.@*Methods:@#A total of 441 patients were included. Platelet reactivity was measured by light transmittance aggregometry after receiving dual antiplatelet therapy. HTPR was defined by the consensus cutoff of maximal platelet aggregation >46% by light transmittance aggregometry. CYP2C19 loss-of-function polymorphisms were identified by DNA microarray analysis. The data were compared by binary logistic regression to find the risk factors. The primary endpoint was major adverse clinical events (MACEs), and patients were followed for a median time of 29 months. Survival curves were constructed with Kaplan-Meier estimates and compared by logrank tests between the patients with HTPR and non-HTPR.@*Results:@#The rate of HTPR was 17.2%. Logistic regression identified the following predictors of HTPR: age, therapy regimen, body mass index, diabetes history, CYP2C19*2, or CYP2C19*3 variant. The area under the curve of receiver operating characteristic for the HTPR predictive model was 0.793 (95% confidence interval: 0.738–0.848). Kaplan-Meier analysis showed that patients with HTPR had a higher incidence of MACE than those with non-HTPR (21.1% vs. 9.9%; χ2 = 7.572, P = 0.010).@*Conclusions:@#Our results suggest that advanced age, higher body mass index, treatment with regular dual antiplatelet therapy, diabetes, and CYP2C19*2 or CYP2C19*3 carriers are significantly associated with HTPR to clopidogrel. The predictive model of HTPR has useful discrimination and good calibration and may predict long-term MACE.

Current status of secondary prevention medication usage and their relation with on-treatment platelet reactivity / 中国介入心脏病学杂志

Objective To observe the current status of secondary prevention medication usage and their relation with on-treatment platelet reactivity in patients with Acute Coronary Syndrome(ACS) treated with aspirin and clopidogrel. Methods A total of 176 patients hospitalized from 2014 to 2015 due to ACS in the Department of Cardiology, Peking University People's Hospital were enrolled and on-treatment platelet reactivity was tested by thromboelastography(TEG)and CYP2C19*2,*3 and*17 alleles were analysed. Details of secondary prevention medication and patients' clinical characteristics were recorded. The relation of secondary prevention medication and on-treatment platelet reactivity was analyzed by multi-logistic regression after adjusting for CYP2C19 alleles and clinical characteristics covariates.Results A 94.89% of patients was treated with statins while 80.68% with beta blocker. The platelet inhibition rate were (45.33±28.78)% and the high on-treatment platelet reactivity (HTPR) rate tested by TEG was 37.50%. In the multivariate logistic regression analysis, usage of β-blockers during hospitalization as well as phenotypes of CYP2C19*2,*3 and *17,clinical presentation with ST-segment elevation myocardial infarction and the length of stents were associated with HTPR defi ned by TEG. The percentage of HTPR rate was signifi cantly lower in patients treated with than those without β-blockers (72.73% vs. 85.45%,OR 0.18,95%CI 0.06-0.53,P=0.002)after adjusting genetic factors and other covariates.Conclusions There was a signifi cant correlation between beta blockers usage and high clopidogrel on-treatment platelet reactivity.

Evaluation of clopidogrel response variability and identification of the CYP2C19 polymorphism in Mexican patients / Evaluación de la variabilidad en la respuesta a clopidogrel e identificación del polimorfismo CYP2C19 en pacientes mexicanos

Abstract Objective Drug inhibition of platelet P2Y12 adenosine diphosphate receptor has reduced the incidence of adverse cardiovascular events after percutaneous coronary interventions. The analysis of the phosphorylation status of vasodilator-stimulated phosphoprotein by flow cytometry has shown a predictive value for adverse events and stent thrombosis. Polymorphisms of CYP2C19 in high risk patients may also relate to adverse cardiovascular events. Methods Ninety patients were enrolled. Patients received a 600 mg clopidogrel loading dose. Blood samples were obtained at the time of the procedure and 24 h later, platelet reactivity was assessed by vasodilator-stimulated phosphoprotein phosphorylation measurement using flow cytometry. Low response to clopidogrel was defined as a platelet reactivity index ≥ 50%. The presence of CYP2C19*2 was identified with the restriction enzyme Smal. Results Mean platelet reactivity index: 53.45 ± 22.48% in the baseline sample and 57.14 ± 23.08% at 24 h (p = 0.183); 40% of patients behaved as good responders, the rest behaved as non-responders with 38% of patients showing platelet reactivity indexes between 50-70% and 22% showing indexes above 70%. The CYP2C19*2 polymorphism was found in 17% of patients, with a 3.9% AA homozygous genotype carriers. Conclusion Response to the clopidogrel loading dose showed a wide variability among patients with 40% responding to the drug according to previously established cut-off values. Our results showed that 3.9% of patients show the AA genotype. To our knowledge, this is the first study involving clopidogrel response by flow citometry and genotype typification in Mexican Mestizo population.

Resumen Objetivo La inhibición del receptor plaquetario P2Y12 se ha asociado con reducción en incidencia de eventos cardiovasculares mayores en pacientes sometidos a intervenciones coronarias percutáneas. El estudio de la fosfoproteína estimulada por vasodilatadores mediante citometría de flujo tiene valor predictivo para desarrollo de eventos adversos y trombosis del stent. Los polimorfismos del CYP2C19 en pacientes de alto riesgo pueden también asociarse con eventos adversos. Método 90 pacientes, dosis de carga de clopidogrel: 600 mg. Se obtuvieron muestras de sangre basales y post-24 horas. La reactividad plaquetaria se estudió mediante medición de fosfoproteína estimulada por vasodiatadores por citometría de flujo. Se consideró baja respuesta al clopidogrel un índice de reactividad plaquetaria ≥50%. La presencia del CYP2C19*2 se identificó con enzima de restricción Smal. Resultados La media del índice de reactividad plaquetaria fue: 53.45 ± 22.48% en muestras basales y 57.14 ± 23.08% a 24 h (p = 0.183); 40% de los pacientes repondieron a clopidogrel, el resto de comportó como no-respondedores, un 38%, mostró índices de reactividad plaquetaria entre 50 -70% y 22%, índices > 70%. El polimorfismo CYP2C19*2 se encontró en 17% pacientes, con un 3.9% portadores de genotipo homozigótico AA. Conclusiones La respuesta a clopidogrel mostró amplia variabilidad entre pacientes, el 40% presentó respuesta de acuerdo con puntos de corte pre establecidos. Un 3.9% de los pacientes presentó genotipo AA. Consideramos que este es el primer estudio realizado en población mestizo-mexicana utilizado citometría de flujo para evaluar la respuesta a clopidogrel así como la tipificación genética de los pacientes.

Safety and efficacy of policosanol in elder patients with high on-treatment platelet reactivity after ;drug-eluting stent implantation:a subgroup analysis of the SPIRIT study / 中国介入心脏病学杂志

Objective To explore the safety and efficacy of policosanol in elder patients with high on-treatment platelet reactivity ( HPR) after drug-eluting stent ( DES) implantation. Methods This study was a prespecified subgroup analysis of the multicenter, randomized SPIRIT trial,in which there were a total of 169 elder patients (≥60 years old) with HPR. Among these patients, 30 patients were in group A ( given clopidogrel 75 mg/d for one year) , 75 patients in group B ( given clopidogrel 150 mg/d for 30 days followed by 75 mg/d until one year ) and 64 patients in group C ( given policosanol 40 mg/d for 6 month and clopidgrel 75 mg/d for one year ) . All patients were treated with aspirin at the same time. The primary endpoint was the reversion rate of HPR at 30 days (reversion was defined as platelet aggregation ﹤65%). The secondary endpoint was 2-year major adverse cardiac events ( MACE ) rate, which included cardiac death, non-fatal myocardial infarction and ischemic symptoms driven target vessel revascularization. The safety endpoint was any bleeding as defined by the Bleeding Academic Research Consortium ( BARC ) definition. Results At 30 days, the reversion rate of HPR in group C was numerically higher as compared with group A ( 42. 9% vs. 23. 3. 0%, P=0. 068 ) , and similar with group B ( 42. 9% vs. 49. 3%, P=0.447). MACE occurred in 4 (13.3%), 5(6.7%) and 3(4.7%) patients in group A, B and C respictively ( P=0. 352). Bleeding events in group A and group C were both markedly lower in comparison to group B (3. 3% vs. 17. 3% vs. 1. 6%, P=0. 001). At the 24-month follow-up, the MACE-free survival rates were not significantly different (95. 3% vs. 93. 3% vs. 86. 7%, P=0. 146). Conclusions For elder patients with HPR, policosanol reduced platelet reactivity to a similar extent in comparison of high maintenance dose of clopidogrel without increasing bleeding risk.