Thomas Cuisset

Consensus and Future Directions on the Definition of High On-Treatment Platelet Reactivity to Adenosine Diphosphate

The addition of clopidogrel to aspirin treatment reduces ischemic events in a wide range of patients with cardiovascular disease. However, recurrent ischemic event occurrence during dual antiplatelet therapy, including stent thrombosis, remains a major concern. Platelet function measurements during clopidogrel treatment demonstrated a variable and overall modest level of P2Y(12) inhibition. High on-treatment platelet reactivity to adenosine diphosphate (ADP) was observed in selected patients. Multiple studies have now demonstrated a clear association between high on-treatment platelet reactivity to ADP measured by multiple methods and adverse clinical event occurrence. However, the routine measurement of platelet reactivity has not been widely implemented and recommended in the guidelines. Reasons for the latter include: 1) a lack of consensus on the optimal method to quantify high on-treatment platelet reactivity and the cutoff value associated with clinical risk; and 2) limited data to support that alteration of therapy based on platelet function measurements actually improves outcomes. This review provides a consensus opinion on the definition of high on-treatment platelet reactivity to ADP based on various methods reported in the literature and proposes how this measurement may be used in the future care of patients.

High post-treatment platelet reactivity identified low-responders to dual antiplatelet therapy at increased risk of recurrent cardiovascular events after stenting for acute coronary syndrome.

Summary.  Background and objectives: Low response to antiplatelet therapy may be a risk factor for the development of ischemic complications in patients with non‐ST segment elevation acute coronary syndrome (NSTE ACS) undergoing coronary stenting. Methods: We prospectively studied the platelet response to both clopidogrel and aspirin in 106 NSTE ACS consecutive patients undergoing percutaneous coronary intervention (PCI) with stenting. A single post‐treatment blood sample was obtained just before PCI and analyzed by platelet aggregometry using both ADP and arachidonic acid (AA) as agonists to explore the responses to clopidogrel and aspirin, respectively. Patients were divided into quartiles according to the ADP or AA induced maximal intensity of platelet aggregation. Patients of the highest quartile (quartile 4) were defined as the ‘low‐responders’. Results: Twelve recurrent cardiovascular (CV) events occurred during the 1‐month follow‐up. Clinical outcome was significantly associated with platelet response to clopidogrel [Quartile 4 vs. 1, 2, 3: OR (95% CI) 22.4 (4.6–109)]. Low platelet response to aspirin was significantly correlated with clopidogrel low response (P = 0.003) but contributed less to CV events [OR (95%CI): 5.76 (1.54–35.61)]. Conclusions: A post‐treatment ADP‐induced platelet aggregation performed just before PCI identifies low responders to dual antiplatelet therapy with an increased risk of recurrent CV events.

Impact of platelet reactivity on clinical outcomes after percutaneous coronary intervention. A collaborative meta-analysis of individual participant data.

OBJECTIVES The purpose of the study was to systematically evaluate the significance of platelet reactivity on clopidogrel treatment on adverse cardiovascular events using a collaborative meta-analysis using patient-level data for the VerifyNow P2Y12 assay (Accumetrics, San Diego, California). BACKGROUND Clinical evidence has been controversial regarding the influence of clopidogrel on treatment platelet reactivity and ischemic outcomes. METHODS MEDLINE, Scopus, and the Cochrane library databases were searched through January 2010. A database containing individual patient-level time-to-event data was generated from identified studies. The primary outcome of interest was a composite of death, myocardial infarction (MI), or stent thrombosis. Secondary outcomes included the incidence of: 1) death; 2) MI; and 3) stent thrombosis. RESULTS A total of 6 studies with 3,059 patients was included. In each study, clopidogrel responsiveness was assessed using the same point-of-care assay after percutaneous coronary intervention. The primary endpoint occurred more frequently in higher quartiles of P2Y(12) reaction unit (PRU) values: quartile I, 5.8%; quartile II, 6.9%; quartile III, 10.9%; quartile IV, 15.8% (p < 0.001). Taking quartile I as referent, the hazard ratios (HRs) for the primary endpoint were as follows: quartile II, HR: 1.13 (95% confidence interval [CI]: 0.72 to 1.78; p = 0.60); quartile III, HR: 1.82 (95% CI: 1.20 to 2.75; p = 0.005); quartile IV, HR: 2.62 (95% CI: 1.78 to 3.87; p < 0.001). On a continuous scale, every 10-U increase in PRU was associated with a significantly higher rate of the primary endpoint (HR: 1.04; 95% CI: 1.03 to 1.06; p < 0.0001). According to receiver-operating characteristic curve analysis, a PRU value of 230 appeared to best predict death, MI, or stent thrombosis (p < 0.001). A PRU value ≥230 was associated with a higher rate of the composite primary endpoint (HR: 2.10; 95% CI: 1.62 to 2.73; p < 0.0001), as well as the individual endpoints of death (HR: 1.66; 95% CI: 1.04 to 2.68; p = 0.04), MI (HR: 2.04; 95% CI: 1.51 to 2.76; p < 0.001), and stent thrombosis (HR: 3.11; 95% CI: 1.50 to 6.46; p = 0.002). CONCLUSIONS In this collaborative meta-analysis, the level of on-treatment platelet reactivity according to the P2Y(12) assay is associated with long-term cardiovascular events after percutaneous coronary intervention, including death, MI, and stent thrombosis.

Comparison of omeprazole and pantoprazole influence on a high 150-mg clopidogrel maintenance dose the PACA (Proton Pump Inhibitors And Clopidogrel Association) prospective randomized study.

OBJECTIVES This study sought to compare the effect of 2 proton pump inhibitors (PPIs) on platelet response to clopidogrel after coronary stenting for non-ST-segment elevation acute coronary syndrome (NSTE ACS). BACKGROUND Use of omeprazole has been reported to significantly decrease the clopidogrel antiplatelet effect because of cytochrome P450 interaction. Because all PPIs are metabolized by CYP2C19, but to a varying degree, we hypothesized that the reported negative omeprazole-clopidogrel drug interaction may not be caused by a class effect. METHODS A total of 104 patients undergoing coronary stenting for NSTE ACS were prospectively included and randomized to omeprazole or pantoprazole 20 mg. They received at discharge 75-mg aspirin and 150-mg clopidogrel. Platelet reactivity index (PRI) vasoactive stimulated phosphoprotein (VASP) was used to assess clopidogrel response and adenosine diphosphate (ADP)-induced aggregation for platelet reactivity (ADP-Ag). RESULTS After 1 month, patients receiving pantoprazole had a significantly better platelet response to clopidogrel as assessed with the PRI VASP: 36 +/- 20% versus 48 +/- 17% (p = 0.007). We identified more clopidogrel nonresponders in the omeprazole group than in the pantoprazole group: 44% versus 23% (p = 0.04), odds ratio: 2.6 (95% confidence interval: 1.2 to 6.2). Conversely, we did not observe any significant difference in platelet reactivity with ADP-Ag between the omeprazole and pantoprazole groups: 52 +/- 15% and 50 +/- 18%, respectively (p = 0.29). CONCLUSIONS The present findings suggest the preferential use of pantoprazole compared with omeprazole in patients receiving clopidogrel to avoid any potential negative interaction with CYP2C19.

Effect of Cytochrome P450 Polymorphisms on Platelet Reactivity After Treatment With Clopidogrel in Acute Coronary Syndrome

Genetic polymorphisms of cytochrome P450 (CYP) isoforms may promote variability in platelet response to clopidogrel. This study was conducted to analyze, in 603 patients with non-ST elevation acute coronary syndromes, the effect of CYP3A4, CYP3A5, and CYP2C19 gene polymorphisms on clopidogrel response and post-treatment platelet reactivity assessed by adenosine diphosphate (ADP)-induced platelet aggregation, vasodilator-stimulated phosphoprotein phosphorylation index, and ADP-induced P-selectin expression. The CYP2C19*2 polymorphism was significantly associated with ADP-induced platelet aggregation, vasodilator-stimulated phosphoprotein phosphorylation index, and ADP-induced P-selectin expression in recessive (p <0.01, p <0.007, and p <0.06, respectively) and codominant (p <0.08, p <0.0001, and p <0.009, respectively) models, but the CYP3A4*1B and CYP3A5*3 polymorphisms were not. The CYP2C19*2 allele carriers exhibited the highest platelet index levels in multivariate analysis (p = 0.03). After covariate adjustment, the CYP2C19*2 allele was more frequent in clopidogrel nonresponders, defined by persistent high post-treatment platelet reactivity (ADP-induced platelet aggregation >70%; p = 0.03). In conclusion, the present data suggest that the CYPC19*2 allele influences post-treatment platelet reactivity and clopidogrel response in patients with non-ST elevation acute coronary syndromes.

Dual-antiplatelet treatment beyond 1 year after drug-eluting stent implantation (ARCTIC-Interruption): a randomised trial.

BACKGROUND Optimum duration of dual antiplatelet treatment (DAPT) after coronary stenting remains uncertain, with an unknown efficacy to safety ratio of extended treatment leading to discrepancies between international guidelines and clinical practice. We assessed whether DAPT continuation beyond 1 year after coronary stenting is beneficial. METHODS This analysis was a planned extension of the previously published ARCTIC-Monitoring trial, in which we randomly allocated 2440 patients to a strategy of platelet function testing with antiplatelet treatment adjustment or a conventional strategy after coronary stenting with drug-eluting stent (DES). We recruited patients (aged 18 years or older) scheduled for planned DES implantation at 38 centres in France. After 1 year of follow-up, patients without contraindication to interruption of DAPT were eligible for a second randomisation to this second phase of the study (ARCTIC-Interruption). Using a computer-generated randomisation sequence (1:1; stratified by centre), we allocated patients to a strategy of interruption of DAPT where the thienopyridine was interrupted and single aspirin antiplatelet treatment was maintained (interruption group) or a strategy of DAPT continuation for 6-18 months (continuation group). The primary endpoint was the composite of death, myocardial infarction, stent thrombosis, stroke, or urgent revascularisation, analysed by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00827411. FINDINGS Between Jan 4, 2011, and March 3, 2012, 1259 eligible patients were randomly allocated to treatment in ARCTIC-Interruption: 624 to the interruption group and 635 to the continuation group. After a median follow-up of 17 months (IQR 15-18), the primary endpoint occurred in 27 (4%) patients in the interruption group and 24 (4%) patients in the continuation group (hazard ratio [HR] 1·17 [95% CI 0·68-2·03]; p=0·58). STEEPLE major bleeding events occurred more often in the continuation group (seven [1%] patients) compared with the interruption group (one [<0·5%] patient; HR 0·15 [0·02-1·20]; p=0·073). Major or minor bleedings were also more common in the continuation group compared with the interruption group (12 [2%] patients vs three [1%] patients; HR 0·26 [0·07-0·91]; p=0·04). INTERPRETATION Our finding suggests no apparent benefit but instead harm with extension of DAPT beyond 1 year after stenting with DES when no event has occurred within the first year after stenting. No conclusion can be drawn for high-risk patients who could not be randomised. The consistency between findings from all trials of such interruption suggests the need for a reappraisal of guidelines for DAPT after coronary stenting towards shorter duration of treatment. FUNDING Allies in Cardiovascular Trials Initiatives and Organized Networks (ACTION Study Group), Fondation de France, Sanofi-Aventis, Cordis, Medtronic, Boston Scientific, Fondation SGAM.

ADP-induced platelet aggregation and platelet reactivity index VASP are good predictive markers for clinical outcomes in non-ST elevation acute coronary syndrome

Clopidogrel responsiveness has been proposed to be involved in recurrent ischemic events after stenting for non-ST elevation acute coronary syndromes (NSTE ACS). However, its biological definition is not consensual. We assess the value of ADP-induced platelet aggregation (ADP-Ag) and platelet reactivity index VASP (PRI VASP) in predicting recurrent ischemic events in patients with NSTE ACS undergoing percutaneous coronary intervention (PCI). We studied 195 consecutive NSTE ACS patients undergoing PCI after a 600 mg loading dose of clopidogrel. ADP-Ag and PRI VASP were analysed. The primary end-point was recurrent ischemic events within 30 days of PCI. It occurred in 14 patients (7%). Construction of ROC curves to examine the value of predictive models showed that sensitivity and specificity for primary endpoint were 79% and 76%, respectively, for a maximal intensity of ADP-Ag >or=70%, 93% and 50% for PRIVASP > 53%. The positive and negative predictive values were 21% and 98%, respectively, for ADP-Ag >or=70%, 12% and 99% for PRIVASP > 53%. In patients with NSTE ACS undergoing PCI, ADP-Ag and PRI VASP identify low responders to clopidogrel with an increased risk of recurrent ischemic events with respective cut-off values of 70% and 53%.

Bleeding and stent thrombosis on P2Y12-inhibitors: collaborative analysis on the role of platelet reactivity for risk stratification after percutaneous coronary intervention

AIMS Although platelet reactivity during P2Y12-inhibitors is associated with stent thrombosis (ST) and bleeding, standardized and clinically validated thresholds for accurate risk stratification after percutaneous coronary intervention (PCI) are lacking. We sought to determine the prognostic value of low platelet reactivity (LPR), optimal platelet reactivity (OPR), or high platelet reactivity (HPR) by applying uniform cut-off values for standardized devices. METHODS AND RESULTS Authors of studies published before January 2015, reporting associations between platelet reactivity, ST, and major bleeding were contacted for a collaborative analysis using consensus-defined, uniform cut-offs for standardized platelet function assays. Based on best available evidence for each device (exploratory studies), LPR-OPR-HPR categories were defined as <95, 95-208, and >208 PRU for VerifyNow, <19, 19-46, and >46 U for the Multiplate analyser and <16, 16-50, and >50% for VASP assay. Seventeen studies including 20 839 patients were used for the analysis; 97% were treated with clopidogrel and 3% with prasugrel. Patients with HPR had significantly higher risk for ST [risk ratio (RR) and 95% CI: 2.73 (2.03-3.69), P < 0.00001], yet a slight reduction in bleeding [RR: 0.84 (0.71-0.99), P = 0.04] compared with those with OPR. In contrast, patients with LPR had a higher risk for bleeding [RR: 1.74 (1.47-2.06), P < 0.00001], without any further benefit in ST [RR: 1.06 (0.68-1.65), P = 0.78] in contrast to OPR. Mortality was significantly higher in patients with HPR compared with other categories (P < 0.05). Validation cohorts (n = 14) confirmed all results of exploratory studies (n = 3). CONCLUSIONS Platelet reactivity assessment during thienopyridine-type P2Y12-inhibitors identifies PCI-treated patients at higher risk for mortality and ST (HPR) or at an elevated risk for bleeding (LPR).

Predictive value of post-treatment platelet reactivity for occurrence of post-discharge bleeding after non-ST elevation acute coronary syndrome. Shifting from antiplatelet resistance to bleeding risk assessment?

AIMS We assessed prospectively the association between occurrence of post-discharge non-CABG-related TIMI major and minor bleeding and post-treatment platelet reactivity in patients with non-ST elevation acute coronary syndrome (NSTE ACS). METHODS AND RESULTS Five hundred and ninety-seven consecutive patients admitted with NSTE ACS were prospectively included. Between hospital discharge and one month follow-up, we observed 16 (2.7%) non-CABG-related TIMI haemorrhagic complications including five (0.84%) major and 11 (1.8%) minor bleeds. Patients with bleeding had significantly lower post-treatment values of ADP-induced aggregation (43+/-14% versus. 56+/-19%, p=0.002) and platelet reactivity index VASP (43+/-14% versus 54+/-23%; p=0.04) and a trend for lower values of arachidonic acid-induced aggregation (2.4+/-5.4 versus 13+/-21; p=0.27). After stratification by quartiles based on post-treatment ADP-induced platelet aggregation, we identified patients in the first quartile as hyper-responders with very low post-treatment platelet reactivity, below <40%. The risk of TIMI major and minor bleeding was significantly higher in the first quartile of hyper-responders than in the others quartiles: 10 (6.6%) versus six (1.4%), p=0.001. CONCLUSIONS Our results suggest that assessment of post-treatment platelet reactivity might be used to detect hyper-responders to antiplatelet therapy with higher risk of non-CABG related bleeding and tailor antiplatelet therapy according to both ischaemic and bleeding risk.

The CYP2C19*17 allele is associated with better platelet response to clopidogrel in patients admitted for non-ST acute coronary syndrome.

Clopidogrel is a thienopyridine derivative that inhibits ADPinduced platelet aggregation. It is an inactive pro-drug that requires several biotransformation steps before it acquires its antiplatelet effect [1,2]. After intestinal absorption, clopidogrel requires oxidation by hepatic cytochrome P450 (CYP) to generate an active metabolite. This active metabolite inhibits platelet activation through irreversible binding to the platelet ADP receptor, P2Y12. Numerous studies have reported inter-individual variability in platelet response to clopidogrel, which is of clinical relevance with regard to patient treatment [3]. However, the mechanisms underlying this variability remain unclear. Putative explanations for variable clopidogrel response include genetic variations that influence the liver metabolism of clopidogrel. Several functional polymorphisms in genes encoding CYP have already been evaluated. Previous studies reported that the CYP3A4*1B and CYP3A5*3 polymorphisms could not explain the variability in the platelet inhibitory effects of clopidogrel [4,5]. In contrast, recent data have shown that the CYP2C19*2 loss-of-function allele is associated with a marked decrease in platelet response to clopidogrel in young healthy male volunteers [6] and in patients with coronary artery disease [7,8]. Moreover, this polymorphism has recently been associated with a poor clinical prognosis [9–11] and with an increased risk of thrombosis after coronary stent placement [12]. Recently, novel allelic variants of the CYP2C19 have been described including the CYP2C19*17 which is associated with ultrarapid enzyme activity and increased medication metabolism including omeprazole [13]. The aim of the present study was to evaluate the impact of these novel allelic variants of the CYP2C19 on platelet response to clopidogrel in patients suffering from non-ST elevation acute coronary syndrome (NSTE ACS). We therefore retrospectively evaluated 598 patients with NSTE ACS after the administration of a 600-mg clopidogrel loading dose, and the impact of CYP2C19*4 CYP2C19*5, CYP2C19*6 and CYP2C19*17 on platelet response to clopidogrel, as assessed using the maximal intensity of 10 lMADPinduced platelet aggregation (ADP-Ag) and by the platelet reactivity index vasodilator stimulated phosphoprotein assay (PRI VASP). All subjects analyzed in this retrospective study participated in a larger study conducted by the same organization to examine the effects of genetic polymorphisms involved in clopidogrel metabolism in NSTE ACS patients [7]. The baseline characteristics of the patients were: age 64.7 ± 12 years, 453 (76%) males, 169 (28%) had diabetes, 332 (56%) suffered from hypertension, 321 (54%) were dyslipidemic, 263 (44%) were current smokers, 336 (45%) were receiving statins, 271 (45%) were treated with betablockers and the body mass index (BMI) was 26.9 ± 4.3 kg.m. All patients were genotyped for CYP2C19*4, CYP2C19*5, CYP2C19*6 and CYP2C19*17. No significant deviations from Hardy–Weinberg equilibrium were observed for any of the genetic variants. Table 1 summarizes the observed frequencies of the CYP variants evaluated in the studied population. CYP2C19*4, CYP2C19*5 and CYP2C19*6 were very rare variants, whereas CYP2C19*17 was relatively common. The baseline characteristics of the patients did not differ between the different groups of genotypes. None of the polymorphisms (CYP2C19*4, CYP2C19*5 or CYP2C19*6) influenced platelet response to clopidogrel (C. Frere, T. Cuisset, B. Gaborit, M.-C. Alessi, J.-S. Hulot, unpublished data). In contrast, the CYP2C19*17 genotype was significantly associated with PRI VASP values, both in recessive (P = 0.02) and codominant (P = 0.0073) models (Table 2). After adjustment for factors that influence platelet reactivity (i.e. age, gender, BMI, diabetes and smoking status), this association remained Correspondence: Corinne Frere, Inserm, U626, 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France. Tel.: +33 491324504; fax: +33 491254336. E-mail: corinne.frere@mail.ap-hm.fr