Reduced Reverse Cholesterol Transport Efficacy in Healthy Men with Undesirable Postprandial Triglyceride Response.

Elevation of nonfasting triglyceride (TG) levels above 1.8 g/L (2 mmol/L) is associated with increased risk of cardiovascular diseases. Exacerbated postprandial hypertriglyceridemia (PP-HTG) and metabolic context both modulate the overall efficacy of the reverse cholesterol transport (RCT) pathway, but the specific contribution of exaggerated PP-HTG on RCT efficacy remains indeterminate. Healthy male volunteers (n = 78) exhibiting no clinical features of metabolic disorders underwent a postprandial exploration following consumption of a typical Western meal providing 1200 kcal. Subjects were stratified according to maximal nonfasting TG levels reached after ingestion of the test meal into subjects with a desirable PP-TG response (GLow, TG < 1.8 g/L, n = 47) and subjects with an undesirable PP-TG response (GHigh, TG > 1.8 g/L, n = 31). The impact of the degree of PP-TG response on major steps of RCT pathway, including cholesterol efflux from human macrophages, cholesteryl ester transfer protein (CETP) activity, and hepatic high-density lipoprotein (HDL)-cholesteryl ester (CE) selective uptake, was evaluated. Cholesterol efflux from human macrophages was not significantly affected by the degree of the PP-TG response. Postprandial increase in CETP-mediated CE transfer from HDL to triglyceride-rich lipoprotein particles, and more specifically to chylomicrons, was enhanced in GHigh vs GLow. The hepatic HDL-CE delivery was reduced in subjects from GHigh in comparison with those from GLow. Undesirable PP-TG response induces an overall reduction in RCT efficacy that contributes to the onset elevation of both fasting and nonfasting TG levels and to the development of cardiometabolic diseases.

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

BACKGROUND: The 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 RESULTS: A 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). CONCLUSIONS: During 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.

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.

Intravenous Clopidogrel (MDCO-157) Compared with Oral Clopidogrel: The Randomized Cross-Over AMPHORE Study.

BACKGROUND: The extent of P2Y12 inhibition during coronary intervention is an important determinant of ischemic complications. The currently available oral P2Y12 inhibitors are limited by a relatively slow onset of action and variable on-treatment response. OBJECTIVE: Our objective was to determine the pharmacodynamic (PD) dose-antiplatelet response relationship and the pharmacokinetics of MDCO-157, an intravenous formulation of clopidogrel complexed with sulphobutylether betacyclodextrin, and to identify the dose level of MDCO-157 that matches the PD effect of oral clopidogrel 300 mg. METHODOLOGY: A randomized open-label crossover study was performed in 33 healthy adult volunteers to determine the pharmacokinetic (clopidogrel and clopidogrel H4 thiol active metabolite) and the PD (vasodilator-stimulated phosphoprotein [VASP]) effects of MDCO-157 at doses of 75, 150, and 300 mg and of oral clopidogrel 300 mg. RESULTS: Data are presented as %, mean (standard deviation). The maximum effect of P2Y12 receptor inhibition assessed by flow cytometry using VASP was 70.42 (6.7), 69.45 (7.1), and 65.58 (12.6) for intravenous MDCO-157 at doses of 75, 150, and 300 mg, respectively, compared with 56.6 (17.5) with oral clopidogrel 300 mg administration (p < 0.0001). Intravenous administration of MDCO-157 led to a stepwise increase in plasma exposure of clopidogrel, higher than with administration of an oral dose of 300 mg (p < 0.0001). Plasma exposure of H4-thiol also increased with intravenous dose (3.6 ± 2.6, 6.9 ± 4.6, and 12.4 ± 9.1 h·ng/ml for intravenous 75, 150, and 300 mg, respectively) but was lower than with oral administration of a 300-mg dose (34.0 ± 16.0 h.ng/ml; pairwise p < 0.0001). CONCLUSIONS: MDCO-157, an intravenous formulation of clopidogrel complexed with sulphobutylether betacyclodextrin, did not show significant platelet inhibition when administered at doses up to 300 mg. Higher doses with longer infusion may be needed to reach a sufficient threshold of active metabolite generation. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01860105.

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.

Prasugrel but not high dose clopidogrel overcomes the lansoprazole neutralizing effect of P2Y12 inhibition: Results of the randomized DOSAPI study.

AIMS: The potential negative metabolic interaction between proton pump inhibitors and clopidogrel is an unsolved issue. We hypothesized that doubling the clopidogrel maintenance dose (150 mg) would be less effective than switching to prasugrel 10 mg maintenance dose (MD) to overcome this negative interaction. METHOD AND RESULTS: In a randomized study with a factorial design, 82 stable coronary artery disease patients treated with 75 mg clopidogrel MD and aspirin were assigned to receive in a double blind fashion lansoprazole (30 mg/day) or placebo and to receive in an open fashion 150 mg clopidogrel MD or 10 mg prasugrel MD. The primary endpoint was the relative change in residual platelet reactivity over the 14-day study period [(RPA14day-RPAbaseline)/RPAbaseline]. The effect of doubling the clopidogrel MD on relative change in RPA was neutralized by lansoprazole (-53.6±48.4% versus +0.8±53.7% without and with lansoprazole, respectively, p = 0.02) whereas 10 mg of prasugrel MD dramatically reduced RPA irrespective of lansoprazole co-administration (-81.8 %±24.8% vs. -72.9%±32.9% without and with lansoprazole, respectively, p = NS). Lansoprazole exposure was the only parameter with a significant interaction with RPA among subgroups. CONCLUSION: The higher platelet inhibitory effect obtained by doubling the clopidogrel MD was totally neutralized by the co-administration of lansoprazole. This drug interaction was not observed with prasugrel 10 mg.

Impact of red blood cell transfusion on platelet aggregation and inflammatory response in anemic coronary and noncoronary patients: the TRANSFUSION-2 study (impact of transfusion of red blood cell on platelet activation and aggregation studied with flow cytometry use and light transmission aggregometry).

OBJECTIVES: This study sought to determine whether red blood cell (RBC) transfusion increases in vivo platelet aggregation and inflammation in coronary and noncoronary patients. BACKGROUND: RBC transfusion increases in vitro platelet activation and aggregation in healthy volunteers, providing a possible explanation for the increase in recurrent ischemic events and mortality reported after RBC transfusion in patients with acute coronary syndromes (ACS). METHODS: Platelet reactivity was measured before and after RBC transfusion in 61 patients (33 with ACS patients and 28 without ACS). Relative changes between baseline and post-transfusion measurements of maximal and residual platelet aggregation were considered with different agonists as well as changes in vasodilator-stimulated phosphoprotein platelet reactivity index and P-selectin expression. Inflammatory and thrombotic biomarkers were also measured before and after transfusion. RESULTS: After RBC transfusion, platelet reactivity was increased when measured using adenosine diphosphate-induced light transmission aggregometry (11.6% relative increase in maximal platelet aggregation, p = 0.004; 10.8% increase in residual platelet aggregation, p = 0.005) and vasodilator-stimulated phosphoprotein platelet reactivity index (20.7% relative increase, p = 0.002), and there was a nonsignificant trend toward an increase in P-selectin expression. Similar results were found with the nonspecific agonist thrombin receptor-activated peptide (relative increases of 11.7% for maximal platelet aggregation, p = 0.04, and 12.7% for residual platelet aggregation, p = 0.02) but not with collagen or arachidonic acid agonists. There were no significant differences in inflammatory and thrombotic biomarkers before and after transfusion. CONCLUSIONS: After RBC transfusion, there is an increase in platelet reactivity, especially with tests measuring the adenosine diphosphate-P2Y12 receptor pathway, without significant variations in inflammatory or thrombotic biomarkers. This in vivo effect may account for the excess of ischemic events observed in the context of patients with ACS treated using percutaneous coronary intervention and P2Y12 inhibitors.

High doses of clopidogrel to overcome genetic resistance: the randomized crossover CLOVIS-2 (Clopidogrel and Response Variability Investigation Study 2).

OBJECTIVES: This study sought to determine whether the pharmacokinetic (PK) and pharmacodynamic (PD) responses to high or standard clopidogrel loading doses (LDs) differ according to CYP2C19*2 allele. BACKGROUND: CYP2C19 loss-of-function alleles are associated with reduced responsiveness to standard clopidogrel doses. METHODS: Young post-myocardial infarction patients heterozygous (wild type [wt]/*2, n = 43) or homozygous (*2/*2, n = 8) for the CYP2C19*2 genetic variant were matched with patients not carrying the variant (wt/wt, n = 58). All patients were randomized to a 300- or 900-mg clopidogrel LD. The relative reduction in residual platelet aggregation (RR-RPA, %) and the area under the plasma concentration time curve of active metabolite from baseline to 6 h after loading (AUC(0-6)) were compared according to both LD and CYP2C19*2 carriage. RESULTS: The 300-mg LD led to a gene-dose effect for RR-RPA (-65.7% ± 35.9% in wt/wt vs. -48.0% ± 38.4% in wt/*2 vs. -14.6% ± 32.4% in *2/*2; overall p value = 0.003, p = 0.03 for wt/wt versus wt/*2, p = 0.04 for wt/*2 versus *2/*2) with minor effect in *2/*2 carriers. After the 900-mg LD, the effect of the CYP2C19*2 variant on platelet inhibition was fully compensated in wt/*2 carriers but not in *2/*2 carriers (-83.6% ± 25.8% in wt/wt vs.-77.2% ± 26.9% in wt/*2 vs. -29.5% ± 26.8% in *2/*2; overall p value = 0.0003, p = 0.20 for wt/wt versus wt/*2, p < 0.001 for wt/*2 versus *2/*2). A similar pattern was observed for the active metabolite AUC(0-6) according to carriage of CYP2C19*2 for both LDs. There was a significant correlation between PK and PD responses irrespective of the LD. CONCLUSIONS: Carriers of CYP2C19*2 display significantly lower responses to clopidogrel with a gene-dose effect. Clopidogrel resistance can be overcome by increasing the dose in heterozygous carriers but not in homozygous carriers. (Clopidogrel and Response Variability Investigation Study 2 [CLOVIS-2]; NCT00822666).