Clopidogrel Intake Research Articles

Frequency of dyspnea related to intake of ticagrelor or clopidogrel in patients with chronic coronary syndrome undergoing coronary intervention

In patients with chronic coronary syndrome, ticagrelor decreases cardiovascular events more efficiently than clopidogrel. In several studies investigating novel P2Y12 inhibitors dyspnea has been detected. A rise of adenosine blood levels is supposed to be one of cases of dyspnea induced by ticagrelor. Dyspnea is a prevalent and complex symptom. It is associated with deterioration of the quality of life and hospital readmission.Aim. To determine the frequency of dyspnea related with ticagrelor or clopidogrel intake in patients with stable coronary artery disease undergoing coronary intervention. Also, to determine which patients could continue ticagrelor intake and which patients couldn’t, and show the causes of ticagrelor discontinuation.Material and methods. Between October 2023 and January 2024, an observational prospective comparative case-control study was conducted at Baghdad Heart Center in Baghdad Teaching Hospital in Medical City. In this study, individuals with stable coronary artery disease who just had therapeutic catheterization and dual antiplatelet therapy were included. The patients from group 1 received aspirin and ticagrelor, while those from group 2 received aspirin and clopidogrel.Results. A total of 120 patients were included. With the ticagrelor intake, the severity of dyspnea was classified as mild 64.2% (77 [120]) and moderate 19.1% (23 [120]). About 16.7% (20 [120]) had no dyspnea at all. The difference between patients who continued ticagrelor intake (16%) and those who stopped using it (84%) was significant. With clopidogrel intake no dyspnea was recorded.Conclusions. According to our findings, the risk or occurrence of dyspnea is only evident in patients who received ticagrelor. When compared to irreversible P2Y12 inhibitors like clopidogrel, the reversible P2Y12 antagonist ticagrelor has a higher incidence of dyspnea in increasing order.

Effect of clopidogrel vs. aspirin on pro-atherosclerotic NLRP1 inflammasome expression in endothelial cells. ECLOAS study

Introduction and objectivesNRP1 inflammasome is crucial in endothelial dysfunction. Platelets are mandatory for the inflammation that precedes it. Aspirin could inhibit NLRP1 inflammasome in endothelial cells, and clopidogrel could also provoke a reduction in vascular inflammation.A study was carried out on the influence of platelet inflammatory inhibition by P2Y receptor inhibition versus COX enzyme inhibition on the transcription of NLRP1 inflammasome in endothelial cells. MethodsAn open-label, prospective, randomised crossover study with two periods of platelet inhibition enrolled 20 healthy volunteers. They received clopidogrel 75mg/day/7days and aspirin 100mg/day/7days. A venous blood sample was collected from all participants before and after this period. Human aortic endothelial cells (HAECs) were exposed for 2h in cultures. NLRP1 gene expression was then analysed in these cultures. ResultsHAEC cultures that were exposed to baseline plasma showed higher expression of NLRP1 than HAECs exposed to plasma after one week of aspirin or clopidogrel intake [relative quantification (RQ), 1.077±0.05 vs. 1.002±0.06; OR, 1.8; 95% CI, 1.1-2.9; P<.01 and 1.077±0.05 vs. 1.04±0.03; OR, 1.7; 95% CI, 1.2-2.6; P<.001, respectively]. NLRP1 expression in HAEC cultures exposed to plasma after one week of aspirin or clopidogrel was similar to that observed in control HAECs that was no exposed to human plasma (PBS) [RQ; 1.002±0.06 vs. 1.009±0.03; OR, 0.9; 95% CI, 0.5-1.4; P=.7, and 1.04±0.03 vs. 1.009±0.03; OR, 0.8; 95% CI, 0.3-1.2; P=.5, respectively]. No difference was observed in NLRP1 percentage reduction in HAEC after aspirin or clopidogrel exposure (3.8% vs. 2.8%, P=.3, respectively). ConclusionsPlatelet inhibition by P2Y pathway is similar to COX pathway in NLRP1 expression inhibition in HAECs.

Efecto del clopidogrel vs. aspirina en la función de la expresión del inflamasoma proaterosclerótico NLRP1 en células endoteliales. Estudio ECLOAS

Introduction and objectivesNRP1 inflammasome is crucial in endothelial dysfunction. Platelets are mandatory for the inflammation that precedes it. Aspirin could inhibit NLRP1 inflammasome in endothelial cells, and clopidogrel could also provoke a reduction in vascular inflammation.A study was carried out on the influence of platelet inflammatory inhibition by P2Y receptor inhibition versus COX enzyme inhibition on the transcription of NLRP1 inflammasome in endothelial cells. MethodsAn open-label, prospective, randomised crossover study with two periods of platelet inhibition enrolled 20 healthy volunteers. They received clopidogrel 75mg/day/7days and aspirin 100mg/day/7days. A venous blood sample was collected from all participants before and after this period. Human aortic endothelial cells (HAECs) were exposed for 2h in cultures. NLRP1 gene expression was then analysed in these cultures. ResultsHAEC cultures that were exposed to baseline plasma showed higher expression of NLRP1 than HAECs exposed to plasma after one week of aspirin or clopidogrel intake [relative quantification (RQ), 1.077±0.05 vs. 1.002±0.06; OR, 1.8; 95% CI, 1.1-2.9; P<.01 and 1.077±0.05 vs. 1.04±0.03; OR, 1.7; 95% CI, 1.2-2.6; P<.001, respectively]. NLRP1 expression in HAEC cultures exposed to plasma after one week of aspirin or clopidogrel was similar to that observed in control HAECs that was no exposed to human plasma (PBS) [RQ; 1.002±0.06 vs. 1.009±0.03; OR, 0.9; 95% CI, 0.5-1.4; P=.7, and 1.04±0.03 vs. 1.009±0.03; OR, 0.8; 95% CI, 0.3-1.2; P=.5, respectively]. No difference was observed in NLRP1 percentage reduction in HAEC after aspirin or clopidogrel exposure (3.8% vs. 2.8%, P=.3, respectively). ConclusionsPlatelet inhibition by P2Y pathway is similar to COX pathway in NLRP1 expression inhibition in HAECs.

Ultrasound-guided peripheral nerve blocks, a safety method of anesthesia in patients with sepsis with an initial acute respiratory failure - presentation of two clinical cases

Anesthetic management of patients with severe sepsis is a great challenge. Systemic inflammation and acute organ dysfunction in response to infection is a major problem, especially respiratory failure and hemodynamic instability. Avoidance of lung injury during mechanical ventilation is possible with peripheral nerve blocks. Clinical case 1 : We present a 73-year-old male hemodialysis patient with sepsis. He had infectious complication of aneurysm formation of A-V fistula. The patient was hypoxic – SpO 2 86-88%, with presence of tachypnea, RR-150/75, HR-125/min, Temp -38 0 C, coagulation abnormalities - INR 1, 58 (clopidogrel intake), elevated CRP and WBC. The patient was indicated for emergency procedures of incision, drainage and ligation of A-V fistula. We performed supraclavicular brachial plexus block + sedation. Clinical case 2 : We present a 61-year-old woman with sepsis, with past medical history of diabetes, COPD, and endometrial cancer. She was with clinical presentation of necrotizing fasciitis of the upper extremity. We performed ultrasound-guided supraclavicular brachial plexus block – ”in plane” technique, 30 mL/25 mL ropivacaine 0.5% in moderate sedated patients. During the operation the patients were conscious, hemodynamically and respiratory stable, with oxygen supply by a mask, and with excellent intraoperative and postoperative pain control. We think that ultrasound-guided peripheral nerve blocks are safe and effective alternatives for septic patients with/without coagulation abnormalities.

Platelet Aggregation Testing on a Routine Coagulation Analyzer: A Method Comparison Study.

Platelet function (PF) plays a pivotal role in both hemostasis and thrombosis, and manual light transmission aggregometry (LTA) is considered the standard of care for platelet function testing but is an error-prone and time-consuming procedure. We aimed to test the agreement regarding maximum aggregation (MA), velocity (VEL), and lag-phase (LagP) of platelet aggregation of the automated Sysmex CS-2100i analyzer (Siemens, Germany) against the APACT 4004 (Elitech, France) in samples derived from healthy participants and patients with hemostaseologic disorders. In total, 123 patient-derived samples were investigated, including 42 patients with acetylsalicylic acid and/or clopidogrel intake and 20 patients with other hemostaseologic disorders. Both MA and VEL showed good or excellent intermethod correlation. Agreement between the testing methods was only partially achieved, and values were indicative for a systematic bias to lower measurements below a threshold of 50% MA with the CS-2100i compared to the APACT 4004. All patients with impaired PF in the APACT 4004 were successfully identified with the CS-2100i, and reference values for automated LTA are provided. Conclusively, automated LTA with the CS-2100i is a highly standardized and reliable PF testing method and represents a decisive step in the simplification of platelet function testing in clinical routine.

High On-Treatment Platelet Reactivity in Danish Hyper-Acute Ischaemic Stroke Patients.

Objective: Early anti-platelet therapy is a cornerstone in the prevention of recurrent ischaemic stroke (IS) and transient ischaemic attacks (TIAs), although the responsiveness to anti-platelet medications varies among patients. Several studies have reported that patients with ischaemic stroke who exhibit high on-treatment platelet reactivity (HTPR) 5–10 days after antiplatelet medication onset, have an increased risk of vascular events. In this study we aim to determine the prevalence of HTPR in the hyper-acute stroke phase less than 48 h from symptom onset, after the administration of a 300 mg bolus of oral clopidogrel in a real-world setting in Danish IS and TIA patients.Material and Methods: In total, 219 Danish patients with acute IS or TIA received 300 mg of oral clopidogrel on admission. Blood samples from all patients were analyzed using the VerifyNow P2Y12 system at 8–24 h after clopidogrel intake. Concomitant therapy and the intervals between ictus and blood collection, clopidogrel intake and blood collection, and blood sampling and analysis were recorded for all patients.Results: HTPR in the hyper-acute stroke phase was observed in 28.8% (63/219) samples. After adjustment for age, sex, co-morbidities, and co-medications, none of the tested variables exhibited an association with HTPR or the platelet reaction unit value measured using the VerifyNow P2Y12 system.Conclusions: The recognition of HTPR to specific anti-platelet agents in the hyper-acute phase after stroke may be the first step toward interventions that may further minimize the early recurrent stroke risk. Further large randomized trials including clinical outcome assessments are necessary.

Myocardial injury after noncardiac surgery-incidence and predictors from a prospective observational cohort study at an Indian tertiary care centre.

Asymptomatic myocardial injury following noncardiac surgery (MINS) is an independent predictor of 30-day mortality and may go unrecognized based on standard diagnostic definition for myocardial infarction (MI). Given lack of published research on MINS in India, our study aims to determine incidence of MINS in patients undergoing noncardiac surgery at our tertiary care hospital, and evaluate the clinical characteristics including 30-day outcome.The prospective observational study included patients >65 years or >45 years with either hypertension (HTN), diabetes mellitus (DM), coronary artery disease (CAD), cerebrovascular accident (CVA), or peripheral arterial disease undergoing noncardiac surgery. MINS was peak troponin level of ≥0.03 ng/dL at 12-hour or 24-hour postoperative. All patients were followed for 30 days postoperatively. Predictors of MINS and mortality were analyzed using multivariate logistic regression. Patients categorized based on peak troponin cut-off values determined by receiver operating characteristic curve were analyzed by Kaplan-Meir test to compare the survival of patients between the groups.Among 1075 patients screened during 34-month period, the incidence of MINS was 17.5% (188/1075). Patients with DM, CAD, or who underwent peripheral nerve block anaesthesia were 1.5 (P < .01), 2 (P < .001), and 12 (P < .001) times, respectively, more likely to develop MINS than others. Patients with heart rates ≥96 bpm before induction of anesthesia were significantly associated with MINS (P = .005) and mortality (P = .02). The 30-day mortality in MINS cohort was 11.7% (22/188, 95% CI 7.5%-17.2%) vs 2.5% (23/887, 95% CI 1.7%-3.9%) in patients without MINS (P < .001). ECG changes (P = .002), peak troponin values >1 ng/mL (P = .01) were significantly associated with mortality. A peak troponin cut-off of >0.152 ng/mL predicted mortality among MINS patients at 72% sensitivity and 58% specificity. Lack of antithrombotic therapy following MINS was independent predictor of mortality (P < .001), with decreased mortality in patients who took post-op ASA (Aspirin) or Clopidogrel. Mortality among MINS patients with post-op ASA intake is 6.7% vs 12.1% among MINS patients without post-op ASA intake. Mortality among MINS patients with post-op Clopidogrel intake is 10.5% vs 11.8% among MINS patients without post-op Clopidogrel intake.A higher (17.5%, 95% CI 15-19%) incidence of MINS was observed in our patient cohort with significant association with 30-day mortality. Serial postoperative monitoring of troponin following noncardiac surgery as standard of care, would identify "at risk" patients translating to improved outcomes.

A Prospective Study on Prevalence and Causes of Anaemia in Patients with Acute Coronary Syndrome.

Anaemia is a contributor for adverse prognosis in Acute Coronary Syndrome (ACS), but the epidemiology and causes of anaemia in such patients is not defined. To study the prevalence and aetiology of anaemia in hospitalized patients with ACS. All consecutive patients admitted with ACS from January to March, 2010 were included. Their clinical information was recorded. Of 130 (87 males) consecutive admissions for ACS, 47.7% had unstable angina, 10% had Non ST-Elevation Myocardial Infarction (NSTEMI) and 42.3% had ST-Elevation Myocardial Infarction (STEMI). Overall prevalence of anaemia (haemoglobin <130 g/l in men and <120 g/l in women) was 51.5% (n=67) and was more prevalent in women (n=30, 69.8%) than men (n=37, 42.5%). Moderate to severe anaemia was more in women (34.9%) compared to men (20.8%). Anaemia was more common in unstable angina patients (58.2%) than in NSTEMI (11.9%) or STEMI (29.9%) patients (p=0.013). Aspirin (p<0.01) and/or clopidogrel intake (p<0.01) and raised serum creatinine (p<0.01) were more often in anaemic patients. Heart failure (p<0.01) and triple vessel disease (p<0.05) were associated with anaemia. Multivariate predictors of duration of hospital stay were haemoglobin (p<0.05) at admission and revascularisation procedure (p=0.01) during hospital stay. The most common cause of anaemia was iron deficiency (29.9%). Anaemia was common in our patients admitted with ACS. Female gender, antiplatelet drug intake and raised creatinine were associated with anaemia, which in turn was associated with adverse in-hospital outcomes. The impact of correcting anaemia on outcomes in ACS needs long term prospective study.

THE “PROTOCOL” STUDY: PRELIMINARY RESULTS

Aim. To reveal the association of gene polymorphism CYP2С19*2 and recurrent early stent thrombosis in coronary vessels, and paradoxal response to clopidogrel intake in patients — the inhabitants of Siberian Region — after acute coronary syndrome. Material and methods. Totally 105 patients studied, hospitalized for stenting of coronary arteries in acute coronary syndrome, never received clopidogrel previously. The polymorphism of studied СУР2С19: *2, *3, *17 alleles, as assessment of platelet aggregation with ADP before and after clopidogrel intake, as of endpoints on safety and efficacy during 30 days (thrombotic complications, bleeding). Results. Within the selected patients there was no any significant association of any CYP2С19*2 and/or CYP2С19*3 alleles and paradoxic laboratory reaction. There was significant association of the CYP2C19*17 gene carriage and bleedings. When comparing the groups of patients having or not having complications related to clopidogrel (thrombotic or bleedings), there was significant difference in residual platelet aggregation. Conclusion. The results of the study might be strongly significant for the decisions making on double antiplatelet therapy and on the tactics of drugs preference.

Carboxylesterase 1 c.428G>A single nucleotide variation increases the antiplatelet effects of clopidogrel by reducing its hydrolysis in humans.

Carboxylesterase 1 (CES1) hydrolyzes the prodrug clopidogrel to an inactive carboxylic acid metabolite. We studied the pharmacokinetics and pharmacodynamics of 600 mg oral clopidogrel in healthy white volunteers, including 10 carriers and 12 noncarriers of CES1 c.428G>A (p.Gly143Glu, rs71647871) single nucleotide variation (SNV). Clopidogrel carboxylic acid to clopidogrel area under the plasma concentration-time curve from 0 hours to infinity (AUC0-∞ ) ratio was 53% less in CES1 c.428G>A carriers than in noncarriers (P = 0.009), indicating impaired hydrolysis of clopidogrel. Consequently, the AUC0-∞ of clopidogrel and its active metabolite were 123% (P = 0.004) and 67% (P = 0.009) larger in the c.428G>A carriers than in noncarriers. Consistent with these findings, the average inhibition of P2Y12 -mediated platelet aggregation 0-12 hours after clopidogrel intake was 19 percentage points higher in the c.428G>A carriers than in noncarriers (P = 0.036). In conclusion, the CES1 c.428G>A SNV increases clopidogrel active metabolite concentrations and antiplatelet effects by reducing clopidogrel hydrolysis to inactive metabolites.

Prevalence of CYP2C19 alleles, pharmacokinetic and pharmacodynamic variation of clopidogrel and prasugrel in Bangladeshi population.

The extent to which cytochrome P450 (CYP) 2C19 genotype influences the effectiveness of clopidogrel remains uncertain due to considerable heterogeneity between studies. We used the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method for genotyping loss of function (LOF) allele, CYP2C19*2 and gain of function (GOF) allele, CYP2C19*17 in 163 patients undergoing PCI and 165 healthy volunteers from an ethnically distinctive Bangladeshi population. Thirty-eight patients took prasugrel and 125 patients took clopidogrel among whom 30 patients had their clopidogrel active metabolites (CAM) determined by LC-MS/MS 1-1.5 h after clopidogrel intake. All patients who underwent PCI had their P2Y12 per cent inhibition (PRI) measured by VerifyNow System. The impact of different genotypes on CAM and PRI were also determined. We did not find significant variation of CYP2C19*2 (P > 0.05) and CYP2C9*17 (P > 0.05) alleles among healthy volunteers and patients. CAM concentration as well as PRI by clopidogrel varied significantly (P < 0.05) based on genotypic variation of CYP2C19*2 and CYP2C19*17 individually. Such influence was not observed in case of prasugrel. Genotypic variation did not impact PRI but as a whole PRI by prasugrel was better than that of clopidogrel (P < 0.05). Due to presence of both of alleles the effect on PRI by clopidogrel could not be predicted, effectively indicating possible involvement of other factors. Genotype guided clopidogrel dose adjustment would be beneficial and therefore we propose mandatory genotyping before clopidogrel dosing. Prasugrel proved to be less affected by genotypic variability, but due to lack of sufficient long-term toxicity data, caution would be adopted before substituting clopidogrel.

Discrepancies in Assessment of Adherence to Antiplatelet Treatment after Myocardial Infarction

The poor response to clopidogrel is multifactorial and includes, amongst others, low patient adherence to medication. The aim of this study was to assess the reported patient adherence to treatment with clopidogrel and confront it with adherence assessed by drug availability. We evaluated determinants of adherence and its impact on platelet aggregation and clinical outcome. The study population comprised 184 patients treated with primary percutaneous coronary intervention for acute myocardial infarction. Follow-up visits were scheduled at 3, 6 and 9 months after discharge. Patient adherence to clopidogrel was defined according to self-reported drug intake and verified based on data from the National Health Fund regarding the purchase of prescribed drugs. The patients were judged as adherent when the proportion of drug availability exceeded 80%. According to drug availability, 100 (54.3%) patients were adherent and 84 (45.7%) were nonadherent. The analysis identified the following factors as predictors of low adherence (<80%): adenosine diphosphate-induced platelet aggregation (ADP-PA) during hospitalization ≤45 U, male gender and occurrence of ST-elevation myocardial infarction [(STEMI) vs. non-STEMI (NSTEMI)], while three-vessel disease was predictive of high adherence to medication. Compared with drug availability-based assessment, self-reported drug intake was significantly different: 172 (94.5%) patients reported regular and 10 (5.5%) patients reported irregular intake of clopidogrel. Clinical follow-up suggested that the self-reported nonregular clopidogrel intake may discriminate patients with a high risk of cardiovascular events. We demonstrated a huge discrepancy between the two most widely used methods for the evaluation of adherence to clopidogrel in secondary prevention treatment in patients after STEMI and NSTEMI. ADP-PA during hospitalization ≤45 U, male gender and STEMI (vs. NSTEMI) were independent predictors of nonadherence while three-vessel disease was independently predictive of adherence to treatment with clopidogrel in the investigated population.

EFFECTS OF PREOPERATIVE ENOXAPARIN ON BLEEDING AFTER CORONARY ARTERY BYPASS SURGERY.

Low molecular weight heparins are replacing unfractionated heparin in practice prior to cardiac surgery. This study examines postoperative (post-op) bleeding indicators in patients who received enoxaparin and underwent elective isolated first time coronary artery bypass graft. A total of 125 consecutive patients who underwent this procedure between 2009 and 2011 at one tertiary center were reviewed and divided into three groups: Group A (n = 50) received the last dose of enoxaparin between 12 and 24 hours before surgery, Group B (n = 25) received the last dose before 24 hours and Group C (n = 50) did not receive enoxaparin. Perioperative bleeding indicators and transfusion rates were compared. Preoperative patients' characteristics were comparable between the three groups. There were no perioperative deaths, return to the operating room for any reason, nor major bleeding. Post-op bleeding indicators were similar in the three groups. The average chest tube drainage at 24 hours post-op was 880 mL, 695 mL and 830 mL in Group A, B and C respectively (p = 0.71). Transfusion rates of red blood cells were not statistically different (Group A 56%, B 64% & C 62%; p = 0.747). In multivariate analysis, female gender, older age, and preoperative clopidogrel intake (stopped 5 days prior to surgery) were associated with higher transfusion rates. In elective first time coronary artery bypass graft patients who had no aspirin or clopidogrel intake 5 days prior to surgery, the use of enoxaparin up to 12 hours prior to skin incision does not increase the risk of post-op bleeding.

Clusterin/Apolipoprotein J immunolocalization on carotid artery is affected by TNF-alpha, cigarette smoking and anti-platelet treatment.

BackgroundClusterin (CLU) /Apolipoprotein J is a protein biosensor of oxidative stress and inflammation, which is upregulated in many pathological processes including atherosclerosis. Previous studies have shown that in aortic tissue, CLU expression increases with atherosclerotic lesion progression and it has been coupled with vascular damage and coronary artery disease. A few studies enter into CLU and carotid atherosclerosis while the apolipoprotein’s expression on human carotid tissue and its association with parameters related to the disease development has not been examined. The present study was designed to reveal the relationships between the degree of CLU immunolocalization on carotid artery and demographic characteristics, blood parameters and pharmacological treatment of patients underwent internal carotid artery endarterectomy.MethodsCLU expression was detected by immunohistochemistry in 42 carotid endarterectomy specimens. Patients’ serum levels of tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), high sensitive C-reactive protein (hsCRP) and classical parameters related to atherosclerosis such as lipid profile, as well as thrombosis related parameters such as fibrinogen, antithrombin III, protein C and protein S were determined. Demographic characteristics, smoking habits and the use of medications were recorded. Comparisons between groups were performed by students’t-test and analysis of variance. Independent associations with CLU expression on carotid tissue were denoted by linear regression analysis.ResultsCLU imuunolocalization was denser in smokers than in non-smokers (p = 0.041) while it was rarefied in specimens of patients on cropidogrel treatment (p = 0.045) compared to the rest not taking this medication. Clopidogrel intake was independent predictor of lower CLU expression on carotid artery (p =0.045). CLU was positively correlated with serum TNF-a concentration (r = 0.33, p = 0.040) that was independent predictor of higher expression of the apolipoprotein (p = 0.001). IL-6, hsCRP and classical parameters related to atherosclerosis and thrombosis were not associated with CLU immunolocalization.ConclusionOur study suggests that CLU expression on carotid artery is affected by TNF-alpha, cigarette smoking confirming its association with oxidative and cellular stress and anti-platelet medication reflecting the protective effects of such pharmacological treatment on vascular wall.

Influence of CYP2C19 and P2Y hotspot mutations on high platelet reactivity in patients with clopidogrel intake

Objective To investigate high platelet reactivity effective and relative strength that induced by the CYP2C19 and P2Y hotspot mutations, and explore the applicable testing methods in clinical settings. Methods A case-control study was conducted.104 patients with coronary heart disease were enrolled who administered antiplatelet agent treatment and a 300 mg loading dose of clopidogrel within 12-24h before a PCI.ADP inhibition rate was tested by TEG and flow cytometry method was used to detect VASP index (PRI) and CD62p.The citrated and heparined venous whole blood collected should be collected within 12-24 h after PCI.Genotyping was carried out by pyrophosphate method for the hotspot mutations of drug metabolism in Chinese population concluded CYP2C19 * 2 (681G> A), CYP2C19 * 3 (636G> A)and the platelet glycoprotein receptor gene concluded P2Y1 (893C> T) and P2Y12 (52G> T).According to the CYP2C19 * 2 sequencing results, patients were grouped into three groups, the wild-type group (*1/*1), the heterozygous group (*1/*2)and the homozygous group(*1/*2).Combined with other three mutation sites, platelet function was analyzed among different groups.One-Way ANOVA was used for analysis of variance between groups of different genotypes, and t test and non-parametric test were selected for statistical analysis between the two groups. Results The PRI of wild-type group (35.75±23.11)% was significantly lower (F=9.170, P 0.05) was existed on CD62p among the wild-type group (9.38±11.16)%, the heterozygous group (9.45±8.91)% and homozygous group (10.87±8.31)%.One P2Y12 (52G> T) mutation was found while no P2Y1 (893C> T) mutation was detected among 37 patients. Conclusion The risk of a low response to clopidogrel was related to the carry of CYP2C19 loss-of-function alleles, and the change can be effectively reflected by VASP analysis.(Chin J Lab Med, 2014,37:198-202) Key words: Coronary disease; Ticlopidine; Aryl hydrocarbon hydroxylases; Receptors, purinergic P2Y12; Platelet count; Microfilament proteins; Phosphoproteins; Cell adhesion molecules

The CYP2C19*1/*2 Genotype Does Not Adequately Predict Clopidogrel Response in Healthy Malaysian Volunteers

Background. The CYP2C19∗2 allele may be associated with a reduced antiplatelet effect for clopidogrel. Here, we assessed whether CYP2C19∗2 alleles correlate with clopidogrel responsiveness following the administration of clopidogrel in healthy Malaysian volunteers. Methods. Ninety volunteers were genotyped for CYP2C19∗2 and CYP2C19∗3 alleles. Forty-five of 90 volunteers were included in the clopidogrel response studies and triaged into three genotypes, namely, CYP2C19∗1/∗1 (n = 17), CYP2C19∗1/∗2 (n = 21), and CYP2C19∗2/∗2 (n = 7). All subjects received 300 mg of clopidogrel, and platelet reactivity was assessed after a four-hour loading utilizing the VerifyNow-P2Y12 assay. Platelet activity was reported using P2Y12 reaction units (PRUs), and nonresponder status was prespecified at PRU ≥ 230. Results. Following clopidogrel intake, CYP2C19∗2/∗2 carriers had a significantly higher mean PRU compared to the CYP2C19∗1/∗2 and CYP2C19∗1/∗1 (291.0 ± 62.1 versus 232.5 ± 81.4 versus 147.4 ± 87.2 PRU, P < 0.001) carriers. Almost half of the participants (46.7%) were found to be nonresponders (3 were CYP2C19∗1/∗1, 11 were CYP2C19∗1/∗2, and 7 were CYP2C19∗2/∗2). Conclusion. In healthy Malaysian volunteers, CYP2C19∗2 allele was associated with a decrease in platelet responsiveness to clopidogrel. However, clopidogrel nonresponders can be found not only in the carriers of CYP2C19∗2/∗2, but also in the carriers of CYP2C19∗1/∗2 and CYP2C19∗1/∗1. The present paper demonstrated that genotype information does not correlate with clopidogrel response, and genotyping may represent a less robust approach compared to platelet activity testing in guiding clopidogrel therapy.

Friend or Foe? Discussion about Dual Platelet Inhibition as a Salvage Procedure from Imminent Flap Failure

Sir:FigureAntiplatelet drugs and combination therapies are on the rise because or their proven benefits concerning an antithrombotic effect on coronary vessels. Surgeons fear the side effects, including hemorrhage. Nevertheless, both cardiologists and microsurgeons are involved in the patency of small-caliber vessels. In addition, the mechanism of acute coronary syndrome reminds us of the process in microanastomosed and pedicled flaps; similar to myocardium, microsurgical transposed tissue is subjected to ischemia, thrombosis, and endothelial injury. Therefore, the idea suggests transforming the foe into a friend and making use of antiplatelet drugs in microsurgery. This idea is promoted by data acquired through animal models. In animal models, a potential benefit of antiplatelet therapy has been proved in randomized, controlled, double-blind studies.1 Antiplatelet drugs have been shown to result in a significant increase in arterial and venous patency and a decrease in anastomotic thrombus formation. Therefore, this knowledge could be used in clinical practice. We present the case report of a 53-year-old patient whose right breast was reconstructed using a pedicled transverse rectus abdominis musculocutaneous flap. After an inconspicuous initial course, epitheliolysis manifested on the fifth postoperative day, with a rapidly increasing livid coloration of the whole flap between days 7 and 11, suggestive of a no-reflow phenomenon. Therefore, on day 11, a salvage attempt was made. The patient was submitted to double-platelet inhibition therapy consisting of acetylsalicylic acid and clopidogrel. One hundred milligrams of of acetylsalicylic acid was administered daily and clopidogrel was given with a loading dose of 225 mg on the first day of treatment, changing to a 75-mg daily dose on the following days. This treatment was maintained for 4 weeks. After this regimen, the vascular changes ceased and the flap recovered appreciably, leaving only a marginal necrosis in zone IV behind (Fig. 1). In addition, no signs of bleeding were recorded.Fig. 1: Imminent loss of a transverse rectus abdominis musculocutaneous flap affiliated with a no-reflow phenomenon. (Left) The obvious livid coloration in almost the whole flap on postoperative day 11, when dual platelet inhibition therapy started. (Right) The imminent flap loss stopped, and after 10 days of dual platelet inhibition, most of the flap appeared salvaged.Whereas the available data1 strongly suggest a potential benefit of antiplatelet drugs in the prevention of flap failure, the question arises of whether this benefit is paid for by an increased bleeding risk. With regard to continued clopidogrel monotherapy in coronary artery bypass grafting, a significant increase in perioperative blood loss, excessive postoperative hemorrhage, increase in transfusion rate and amount of administered blood products, high reoperation rate, and even mortality have been noted.2 Also, in dermatologic surgery, clopidogrel intake has been found to be significantly associated with hemorrhagic complications.3 Thus, operations performed under continued antiplatelet therapy may be associated with a considerable risk of bleeding. However, what about making use of the positive effect of platelet inhibition by administering the drugs postoperatively? Thus, the bleeding risk should be low and the positive effect must be maintained. We can make use of the experience of cardiac surgeons who routinely operate on patients under acetylsalicylic acid therapy, which is combined with clopidogrel therapy 24 to 48 hours postoperatively. Despite the obvious invasiveness of cardiac operations, studies have shown that this postoperative dual platelet inhibition does not cause any significant increase in bleeding risk when compared with acetylsalicylic acid monotherapy.4,5 Keeping in mind the obvious bleeding risks when administered preoperatively, we suggest examining its potential benefits in microsurgery rather than just considering antiplatelet therapy as a foe when administered postoperatively. Stefan Riml, M.D. Heinz Wallner, M.D. Peter Kompatscher, M.D. Department for Plastic, Aesthetic, and Reconstructive Surgery, Academic Hospital Feldkirch, Feldkirch, Austria ACKNOWLEDGMENT The authors thank A. Piontke for excellent photodocumentation. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication.

042: Real life dual antiplatelet therapy after NSTE-ACS in a Tunisian population: is there a need for 12 months of treatment?

Even if the recommended duration for dual antiplatelet therapy (DAT) after non ST elevation acute coronary syndromes (NSTE-ACS) is 12 months, evidence concerning the benefit of clopidogrel adjunction especially beyond 3 months remains poor. The aim of the study was to assess the effective clopidogrel intake and the incidence of a composite endpoint including all causes death and non fatal myocardial infarction in a Tunisian population after NSTE-ACS. We included patients admitted for NSTE-ACS in our department between January 2010 and August 2011 for whom long term evaluation was possible. In-hospital deaths were excluded (including post operative deaths). By telephone follow up, we evaluated the effective DAT duration and the occurrence of all causes death and non-fatal myocardial infarction. One hundred thirty patients were included. Mean (SD) follow up was 261 (99) days. DAT was effectively observed during 94(103 days (extremes ranging from 0 to 360 days). Angioplasty was performed in 51.5%, coronary artery bypass graft in 8.4% and medical therapy was considered in 40.1%. In 35 (26.9%) patients, aspirin was the only antiplatelet therapy taken after discharge although DAT was prescribed; 46.9% of the patients took the DAT for more than 3 months, and 23.1% for more than 6 months. The composite endpoint occurred in 6 (4.6%) patients: 2 deaths (both of cardiac causes) and 4 myocardial infarctions. Three of them were under DAT, and the 3 others remained event free during 7, 240 and 270 days after clopidogrel withdrawal. These findings suggest that DAT does not protect against death or myocardial infarction. The rebound phenomenon after clopidogrel withdrawal isn’t patent in our population. In the Tunisian context, DAT observance is poor after NSTE-ACS. Death and non fatal myocardial infarction don’t seem to be reduced by DAT and the rebound phenomenon after clopidogrel withdrawal isn’t patent. This may be in part attributed to the small sample of population and the predominantly low risk (as assessed by TIMI risk score), but larger studies are needed to strengthen the evidence for DAT after NSTE-ACS.

Platelet Hyperreactivity and Stent Thrombosis in Patients Undergoing Coronary Stenting

Stent thrombosis (ST) is a rare but very serious event complicating percutaneous coronary intervention (PCI) procedures. Both procedure- and patient-related factors, including inadequate platelet inhibition are well known predictors of ST. According to the present guidelines, a dual antiplatelet treatment regimen consisting of aspirin and a P2Y12 receptor inhibitor such as clopidogrel, prasugrel or ticagrelor is routinely administered to ACS patients and to patients undergoing PCI in order to prevent thrombotic vessel occlusions. In recent years, evidence has grown that patients showing high on-treatment platelet reactivity (HPR) under clopidogrel intake exhibit a higher risk for the occurrence of ischemic events including ST. For assessing HPR, different platelet function assays are currently available and have already found their way into routine clinical practice in several centers. Along with this development, more potent P2Y12 receptor inhibitors like prasugrel and ticagrelor are substitutes for clopidogrel in specific circumstances such as in ACS patients or in patients who do not adequately respond to standard clopidogrel treatment. Utilizing platelet function monitoring, patients showing HPR can be identified and an optimized antiplatelet treatment regime can be tailored for these patients. This review paper aims to summarize the important facts in relation to ST and antiplatelet therapy with a particular focus on P2Y12 receptor inhibition and its ex vivo assessment in patients undergoing coronary stent placement.

Impaired ristocetin–induced Platelet Aggregation in Whole Blood Assessed with a Multiplate© Analyser Suggests a New Mechanism of Antiplatelet Effect of Aspirin and Clopidogrel,

Abstract 3362The five channel computerized Whole Blood Aggregation instrument (Multiple Platelet Function Analyzer or Multiplate®), assesses platelet aggregation based on a modified whole blood impedance aggregation method. It permits platelet aggregation to be measured after adding commonly used agonists as arachidonic acid (ASPItest), ADP (ADPtest), collagen (COLtest), ristocetin (RISTOtest) and TRAP (TRAPtest), by detecting changes in electrical resistance in whole blood. Instrument handling is easy. Results are available within 9 minutes.Our objective was to evaluate the effect of aspirin (irreversible inhibitor of COX-1) and/or clopidogrel (irreversible inhibitor of the platelet P2Y12 receptor) on whole blood platelet aggregations induced by the 5 agonists using the Multiplate® in patients treated by aspirin and/or clopidogrel.Patients and controls. Two hundred and twenty two consecutive patients were recruited: 83 treated daily by 75 or 100 mg aspirin (group A); 42 treated daily by 75 mg clopidogrel (group C); 70 treated daily by 75 or 100 mg aspirin plus 75mg clopidogrel (group AC) and 27 who were daily on 100 mg aspirin before coronary intervention were tested 12 h after dual loading dose of aspirin between 75 et 500 mg and 75 to 900 mg clopidogrel according to cardiologists' recommendations: group loading aspirin-clopidogrel (LAC). Among group AC, 23 consecutive patients requiring intracranial stent placement of supra-aortic vessel were tested first at preoperative, without antiplatelet therapy, then 1 month after initiation of daily continuous dual antiplatelet therapy by 100 mg aspirin + 75mg clopidogrel. Ninety six volunteers without pathology or drugs influencing platelet functions constitute the normal control group (N).Blood samples. All patient and controls gave informed consent prior to blood sampling. Blood samples were collected by venipuncture or obtained from the arterial sheath directly into vacutainer Becton Dickinson tube containing 0.129M sodium citrate.Results. Patients under medication showing lower aggregation values than the arbitrary cutoff (fifth percentile of the aggregation in the normal control group was selected for each agonist) were classified as abnormal and having biological sensitivity to the agonist tested. Aggregation values above the cutoff with ASPItest or ADPtest for patients on antiplatelet agents were considered as a persistent platelet aggregation and as a biological resistance. According to the literature, resistance to aspirin was found in 8.6% of patients under aspirin alone or in combination and in 25.1% of patients under clopidogrel alone or in combination. Our main result shows an inhibition in platelet aggregation using ristocetin as agonist for 73.9% of patients taking aspirin alone, for 27.8% on clopidogrel and in 94% of patients receiving combination of the 2 drugs. This inhibition appears after aspirin + clopidogrel intake as we could observe it among patients candidates for intracranial stent placement tested before and after one month of treatment by dual antiplatelet therapy.This effect is not related to von Willebrand Factor (vWF) deficiency since the measurement of ristocetin cofactor activity, and vWF antigen carried out among 14 patients exhibiting an inhibition in whole blood platelet aggregation using RISTOtest were normal and unchanged before and after antiplatelet treatment. VWF is essential platelet-to-platelet interactions which is promoted by the binding of VWF with platelet-receptor glycoprotein IbIX (GPIbIX).Our results suggest: 1) aspirin inhibits the interaction of vWF to GP IbIX. This inhibition appears increased by the association of clopidogrel to aspirin. 2) a new mechanism of inhibition of the platelet function GPIbIX-vWF dependant conjointly to inhibition of cyclooxygenase by aspirin and P2Y12 receptor by clopidogrel.Table I:Biological sensibility according to the five tests (%) in the 4 groups testedGroup (n)ASPItestADPtestCOLtestRISTOtestTRAPtestA (83)84.312.038.373.98.4C (42)38.176.219.227.816.7AC (70)90.074.348.288.222.9LAC (27)100.074.163.0100.029.6 Disclosures:No relevant conflicts of interest to declare.