Delphine Brugier

Cytochrome P450 2C19 polymorphism in young patients treated with clopidogrel after myocardial infarction: a cohort study.

BACKGROUND Clopidogrel and low-dose aspirin have become the mainstay oral antiplatelet regimen to prevent recurrent ischaemic events after acute coronary syndromes or stent placement. The frequent genetic functional variant 681 G>A (*2) of cytochrome P450 2C19 (CYP2C19) is an important contributor to the wide variability between individuals of the antiplatelet effect of clopidogrel. We assessed whether the CYP2C19*2 polymorphism affected long-term prognosis of patients who were chronically treated with clopidogrel. METHODS Between April 1, 1996, and April 1, 2008, 259 young patients (aged <45 years) who survived a first myocardial infarction and were exposed to clopidogrel treatment for at least a month, were enrolled in a multicentre registry and underwent CYP2C19*2 determination. The primary endpoint was a composite of death, myocardial infarction, and urgent coronary revascularisation occurring during exposure to clopidogrel. Follow-up was every 6 months. The key secondary endpoint was stent thrombosis proven by angiography. FINDINGS Median clopidogrel exposure time was 1.07 years (IQR 0.28-3.0). Baseline characteristics were balanced between carriers (heterozygous *1/*2, n=64; homozygous *2/*2, n=9) and non-carriers (n=186) of CYP2C19*2 variant. The primary endpoint occurred more frequently in carriers than in non-carriers (15 vs 11 events; hazard ratio [HR] 3.69 [95% CI 1.69-8.05], p=0.0005), as did stent thrombosis (eight vs four events; HR 6.02 [1.81-20.04], p=0.0009). The detrimental effect of the CYP2C19*2 genetic variant persisted from 6 months after clopidogrel initiation up to the end of follow-up (HR 3.00 [1.27-7.10], p=0.009). After multivariable analysis, the CYP2C19*2 genetic variant was the only independent predictor of cardiovascular events (HR 4.04 [1.81-9.02], p=0.0006). INTERPRETATION The CYP2C19*2 genetic variant is a major determinant of prognosis in young patients who are receiving clopidogrel treatment after myocardial infarction.

Composition of Coronary Thrombus in Acute Myocardial Infarction

OBJECTIVES We sought to analyze the composition of coronary thrombus in vivo in ST-segment elevation myocardial infarction (STEMI) patients. BACKGROUND The dynamic process of intracoronary thrombus formation in STEMI patients is poorly understood. METHODS Intracoronary thrombi (n = 45) were obtained by thromboaspiration in 288 consecutive STEMI patients presenting for primary percutaneous intervention, and analyzed using high-definition pictures taken with a scanning electron microscope. Plasma biomarkers (TnI, CRPus, IL-6, PAI-1, sCD40 ligand, and TNF-α) and plasma fibrin clot viscoelastic properties were measured simultaneously on peripheral blood. RESULTS Thrombi were mainly composed of fibrin (55.9 ± 18%) with platelets (16.8 ± 18%), erythrocytes (11.5 ± 9%), cholesterol crystals (5.2 ± 8.4%), and leukocytes (1.3 ± 2.0%). The median ischemic time was 175 min (interquartile range: 140 to 297). Ischemic time impacted thrombi composition, resulting in a positive correlation with intracoronary thrombus fibrin content, r = 0.38, p = 0.01, and a negative correlation with platelet content, r = -0.34, p = 0.02. Thus, fibrin content increased with ischemic time, ranging from 48.4 ± 21% (<3 h) up to 66.9 ± 9% (>6 h) (p = 0.02), whereas platelet content decreased from 24.9 ± 23% (<3 h) to 9.1 ± 6% (>6 h) (p = 0.07). Soluble CD40 ligand was positively correlated to platelet content in the thrombus (r = 0.40, p = 0.02) and negatively correlated with fibrin content (r = -0.36; p = 0.04). Multivariate analysis indicated that ischemic time was the only predictor of thrombus composition, with a 2-fold increase of fibrin content per ischemic hour (adjusted odds ratio: 2.00 [95% confidence interval: 1.03 to 3.7]; p = 0.01). CONCLUSIONS In acute STEMI, platelet and fibrin contents of the occlusive thrombus are highly dependent on ischemia time, which may have a direct impact on the efficacy of drugs or devices used for coronary reperfusion.

Switching Acute Coronary Syndrome Patients From Prasugrel to Clopidogrel

OBJECTIVES This study sought to assess the consequences of switching prasugrel to clopidogrel on platelet inhibition and clinical outcomes after an acute coronary syndrome (ACS). BACKGROUND Many ACS patients are switched from prasugrel to clopidogrel within the recommended 1-year duration of treatment. METHODS Platelet reactivity was measured with the VerifyNow P2Y(12) assay (Accumetrics, San Diego, California) in 300 ACS patients treated for 15 days with prasugrel 10 mg. Patients displaying low on-treatment platelet reactivity (LPR) and/or at high risk of bleeding were switched to clopidogrel 75 mg and tested again 15 days later. The rate of patients with high on-treatment platelet reactivity (HPR), P2Y(12) reaction units (PRU) >208, and LPR (PRU <0) were evaluated before and after the switch. Bleeding and ischemic events were also recorded. RESULTS On a regimen of prasugrel 10 mg, the rate of patients with LPR was 45.6% (n = 137), whereas 4.3% (n = 13) had HPR. A group of 31 patients (10.3%) was switched to clopidogrel 75 mg, of whom 29 had LPR (93.5%) on a regimen of prasugrel. On-treatment platelet reactivity (PRU) increased from 14 ± 4 on a regimen of prasugrel to 155 ±15 on a regimen of clopidogrel (p = 0.0001), resulting in a much lower rate of patients with LPR (9.7%). The rate of patients with HPR increased from 0% with prasugrel to 29% (n = 9) with clopidogrel. The rate of minor bleeding decreased after the switch from 32.2% to 9.7%; p = 0.03. CONCLUSIONS An LPR is frequent in patients treated with prasugrel 10 mg. Early switching from prasugrel 10 mg to clopidogrel 75 mg reduces the number of patients with LPR and minor bleeding events but unmasks a group of nonresponders to clopidogrel with unknown consequences on clinical outcomes.

Efficacy of Ex Vivo Autologous and In Vivo Platelet Transfusion in the Reversal of P2Y12 Inhibition by Clopidogrel, Prasugrel, and Ticagrelor The APTITUDE Study

Background—Allogenic platelet transfusions (PT) are administered to treat excessive bleeding in patients on P2Y12 receptor inhibitors (RI). We assessed the effect of ex vivo and in vivo PT on platelet activation and aggregation in patients on dual antiplatelet therapy. Methods and Results—In the Antagonize P2Y12 Treatment Inhibitors by Transfusion of Platelets in an Urgent or Delayed Timing After Acute Coronary Syndrome or Percutaneous Coronary Intervention Presentation-Acute Coronary Syndrome (APTITUDE-ACS) study, patients presenting with acute coronary syndrome or for elective percutaneous coronary intervention, receiving loading doses of clopidogrel (600 mg, n=13 or 900 mg, n=12), prasugrel 60 mg (n=10), or ticagrelor 180 mg (n=10) were included. PT was performed ex vivo by mixing platelet-rich plasma from blood sampling performed at baseline in increasing proportions with platelet-rich plasma sampled 4 hours after loading dose. The percentage restoration of residual platelet aggregation achieved with 80% proportion PT (residual platelet aggregation 80% PT mix/residual platelet aggregation baseline×100) significantly decreased with increasing potency of P2Y12 RI (83.9±11%, 73±14%, 66.3±15%, 40.9±19% for clopidogrel 600 mg, clopidogrel 900 mg, prasugrel, and ticagrelor, respectively; P for trend <0.0001). In the APTITUDE-Coronary Artery Bypass Graft (APTITUDE-CABG) study, vasodilator-stimulated phosphoprotein-platelet reactivity index, a specific marker of the P2Y12 RI drug–effect, was assessed before and after in vivo PT administered for excessive bleeding in patients undergoing cardiac surgery while on a maintenance dose of aspirin and clopidogrel (n=45), prasugrel (n=6), or ticagrelor (n=3). When compared with baseline, there was a significant relative increase of 23.1% in platelet activation after PT transfusion (42.2±23.6% versus 56.6±18.2%; P=0.0008). Conclusions—PT restores platelet reactivity in patients with acute coronary syndrome/percutaneous coronary intervention and in patients undergoing cardiac surgery on P2Y12 RI while bleeding with a less effect with increasing potency of P2Y12 inhibition. Clinical Trial Registration—URL: http://www.recherche-biomedicale.sante.gouv.fr/pro/comites/coordonnees.htm and http://www.cnil.fr/. Unique identifiers: No. 301111 and No. 1547216v0.

Platelet reactivity in human immunodeficiency virus infected patients on dual antiplatelet therapy for an acute coronary syndrome: the EVERE2ST-HIV study

Aim To explore platelet reactivity on dual antiplatelet therapy (DAPT) of acute coronary syndrome (ACS) patients infected with HIV. Methods and results Acute coronary syndrome patients infected with HIV (n = 80) were matched to ACS patients without HIV (n = 160) on age, sex, diabetes, and DAPT (aspirin 100%, clopidogrel 68%, prasugrel 31%, ticagrelor 1%). Platelet reactivity was evaluated after ACS (>30 days) by measuring residual platelet aggregation (RPA) to aspirin and to P2Y12 inhibitors with light transmission aggregometry (LTA), VerifyNow aspirin assay (ARU), and P2Y12 assay (PRU) and with the VASP platelet reactivity index (VASP-PRI). Proportion of patients with high residual platelet reactivity (HPR) was evaluated. HIV-infected ACS patients had higher levels of platelet reactivity in response to P2Y12 inhibitors (RPA: 23.8 ± 2.7% vs. 15.3 ± 1.3%; P = 0.001; PRU: 132 ± 10 vs. 107.4 ± 6.6; P = 0.04; and VASP-PRI: 45.2 ± 2.6% vs. 32.0 ± 2.0%; P < 0.001) and to aspirin (RPA: 3.6 ± 1.5% vs. 0.4 ± 0.1%; P = 0.004 and ARU: 442 ± 11 vs. 407 ± 5; P = 0.002) compared with non-HIV. HIV-infection was independently associated with increased platelet reactivity regardless of the test used (RPA: P = 0.005; PRU: P < 0.001 and VASP-PRI: P < 0.001) and a higher proportion of HPR (OR = 7.6; P < 0.001; OR = 2.06; P = 0.06; OR = 2.91; P = 0.004, respectively) in response to P2Y12 inhibitors. Similar results were found with aspirin. Protease inhibitors use was associated with increased platelet reactivity and higher rate of HPR. Conclusions Acute coronary syndrome patients infected with HIV have increased levels of platelet reactivity and higher prevalence of HPR to P2Y12 inhibitors and aspirin than non-HIV patients. These results could provide potential explanations for the observed increase risk of recurrent ischemic events in the HIV-infected population.

Short-term effects of the smoke-free legislation on haemostasis and systemic inflammation due to second hand smoke exposure: The AERER* study

It was the objective of this study to assess the effect of the implementation of the smoke-free legislation on haemostasis and systemic inflammation in second-hand smoking (SHS)-exposed healthy volunteers. Fibrin-rich clot properties, platelet reactivity and inflammatory biomarkers were measured before and four months following the implementation of the smoke-free legislation in gender and age-matched healthy volunteers exposed (n=23, exposed) and unexposed (n=23, controls) to occupational SHS. The primary objective was to compare fibrin-rich clot stiffness before and after implementation of the smoke-free legislation. There was 40% reduction in fibrin-rich clot stiffness following the implementation of the smoke-free legislation in SHS-exposed volunteers (17 ± 7 vs. 10.6 ± 7 dynes/cm², before and after, respectively, p=0.001). These dramatic changes were associated with a 20% reduction in fibrin fiber density (p<0.01) and a 20% reduction in clot lysis time (p=0.05). No change in fibrin properties was observed in the control group of SHS-unexposed volunteers related to the implementation of the smoke-free legislation. Of interest, neither platelet reactivity nor systemic inflammatory biomarkers were changed in either group. The smoke-free legislation is associated with significant changes in fibrin-rich clot properties toward a less thrombogenic conformation with a better fibrinolysis response while neither platelet reactivity nor systemic inflammatory biomarkers are modified. These improvements may explain the observed reduction in acute coronary syndrome following the implementation of the smoke-free legislation.

Thrombus composition in sudden cardiac death from acute myocardial infarction

BACKGROUND AND AIM It was hypothesized that the pattern of coronary occlusion (thrombus composition) might contribute to the onset of ventricular arrhythmia and sudden cardiac death (SCD) in myocardial infarction (MI). METHODS The TIDE (Thrombus and Inflammation in sudden DEath) study included patients with angiographically-proven acute coronary occlusion as the cause of a ST elevation MI (STEMI) complicated by Sudden Cardiac Death (SCD group) or not (STEMI group). Thrombi were obtained by thrombo-aspiration before primary percutaneous coronary stenting and analyzed with a quantitative method using scanning electron microscopy. We compared the composition of the thrombi responsible for the coronary occlusion between the two groups and evaluated factors influencing its composition. RESULTS We included 121 patients and found that thrombus composition was not different between the SCD group (n=23) and the STEMI group (n=98) regarding content of fibrin fibers (60.3±18.4% vs. 62.4±18.4% respectively, p=0.68), platelets (16.3±19.2% vs. 15.616.7±%, p=0.76), erythrocytes (14.6±12.5% vs. 13±12.1%, p=0.73) and leukocytes (0.6±0.9% vs. 0.8±1.5%, p=0.93). Thrombus composition did not differ between patients receiving upstream-use of glycoprotein IIb/IIIa platelet receptor inhibitors (GPI) and patients free of GPI. The only factor found to influence thrombus composition was the ischemic time from symptom onset to primary PCI, with a decreased content in fibrin fibers (57.8±18.5% vs. 71.9±10.1%, p=0.0008) and a higher platelet content (19.2±19.1% vs. 7.9±5.7% p=0.014) in early presenters (<3h of ischemic time) vs. late presenters (>6h of ischemic time). CONCLUSION Composition of intracoronary thrombi in STEMI patients does not differ between those presenting with and without SCD. Time from symptom onset to coronary reperfusion seems to be the strongest factor influencing thrombus composition in MI.

Platelet effect of prasugrel and ticagrelor in patients with ST-segment elevation myocardial infarction.

BACKGROUND Recent studies have suggested that ticagrelor 90mg twice daily provides stronger platelet inhibition than prasugrel 10mg once daily in acute coronary syndrome patients undergoing percutaneous coronary intervention. OBJECTIVES To compare the effects of ticagrelor 90 mg twice daily and prasugrel 10mg once daily on platelet reactivity in patients with ST-segment elevation myocardial infarction (STEMI), using: the VerifyNow(®) P2Y12 (VN-P2Y12) assay, expressed in P2Y12 reaction units (PRU); measurement of the vasodilator-stimulated phosphoprotein platelet reactivity index (VASP-PRI; %); and light transmission aggregometry (LTA), expressed as residual platelet aggregation (RPA; %). METHODS Platelet reactivity was evaluated prospectively using the three assays 30 days after primary PCI in 118 patients with STEMI on a maintenance dose of prasugrel 10mg once daily (n=60) or ticagrelor 90mg twice daily (n=58). RESULTS On-treatment platelet reactivity, assessed by the VN-P2Y12 assay, was lower for ticagrelor compared with prasugrel (20.91 ± 4.59 PRU vs. 43.50±6.98 PRU; P=0.008) but was not significantly different when using the more specific VASP-PRI assay (13.05 ± 1.61% vs. 17.44 ± 1.97%; P=0.09) or RPA assessed by LTA (10.49 ± 1.44% vs. 7.20 ± 1.27%; P=0.09). CONCLUSIONS The difference in platelet reactivity between ticagrelor and prasugrel varies according to the platelet function test in patients with STEMI. The differences observed may be related more to the tests than to the drugs used.

Biomarkers of Thrombosis in ST-Segment Elevation Myocardial Infarction: A Substudy of the ATOLL Trial Comparing Enoxaparin Versus Unfractionated Heparin

BackgroundThe aim was to compare the peri-procedural biomarkers of coagulation and platelet activation in patients randomly allocated to intravenous enoxaparin or unfractionated heparin (UFH) in the ATOLL randomized trial (NCT00718471).Methods and ResultsA total of 129 patients (n = 58 enoxaparin and n = 71 UFH) admitted for ST-segment elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention (PCI) were included in this substudy of the ATOLL trial. Activated partial thromboplastin time ratio, anti-Xa activity, von Willebrand factor antigen, prothrombin fragment 1 + 2 (F1 + 2), thrombin–antithrombin complex (TAT), tissue factor pathway inhibitor and soluble CD40 ligand were measured at sheath insertion (T1) and at the end of the PCI (T2) and correlated with 1-month clinical outcomes. Target anticoagulation levels at T2 were more readily achieved in patients receiving enoxaparin compared to those receiving UFH (80.3 vs 18.2%, p < 0.0001). Increased levels of F1 + 2 and TAT measured at T2 were associated with the incidence of the composite ischemic endpoint (p = 0.04 and p = 0.03) and all-cause mortality (p < 0.0001 and p = 0.002). Release of F1 + 2 between T1 and T2 also predicted the composite ischemic endpoint (312 ± 513 vs 37 ± 292, p = 0.04) and net clinical outcome (185 ± 405 vs 3.2 ± 278, p = 0.03).ConclusionsDuring primary PCI, enoxaparin achieved therapeutic levels more frequently than UFH. Higher level of thrombin generation measured at the end of the PCI procedure was associated with more frequent ischemic events.

EVALUATION OF RESIDUAL PLATELET REACTIVITY AFTER ST ELEVATION MYOCARDIAL INFARCTION IN HUMAN IMMUNODEFICIENCY VIRUS, THE EVRE2ST-HIV STUDY

High on-treatment platelet reactivity is an independent risk factor of major adverse cardiovascular events following percutaneous coronary intervention or Acute Coronary Syndrome (ACS). HIV-infected patients have a higher risk of recurrent events after ACS than HIV uninfected patients. We