RESUMEN
BACKGROUND: High plasma fibrin clot strength (MA) measured by thrombelastography (TEG) is associated with increased risk of cardiac events after percutaneous coronary interventions (PCIs). Factor XIIIa (FXIIIa) cross-links soluble fibrin, shortens clot formation time (TEG-K), and increases final clot strength (MA). METHODS: We analyzed platelet-poor plasma from patients with previous PCI. Kaolin-activated TEG (R, K, MA) in citrate platelet-poor plasma and FXIIIa were measured (n = 257). Combined primary endpoint was defined as recurrent myocardial infarction (MI) or cardiovascular death (CVD). Relationship of FXIIIa and TEG measurements on cardiac risk was explored. RESULTS: FXIIIa correlated with TEG-MA (p = 0.002) and inversely with TEG-K (p < 0.001). High MA (≥35.35 mm; p = 0.001), low K (<1.15 min; p = 0.038), and elevated FXIIIa (≥83.51%; p = 0.011) were associated with increased risk of CVD or MI. Inclusion of FXIIIa activity and low TEG-K in risk scores did not improve risk prediction as compared with high TEG-MA alone. CONCLUSION: FXIIIa is associated with higher plasma TEG-MA and low TEG-K. High FXIIIa activity is associated with a modest increase in cardiovascular risk after PCI, but is less sensitive and specific than TEG-MA. Addition of FXIIIa does not provide additional risk stratification beyond risk associated with high fibrin clot strength phenotype measured by TEG.
RESUMEN
It has been estimated that up to half of circulating factor XIIIa (FXIIIa) is stored in platelets. The release of FXIIIa from platelets upon stimulation with adenosine diphosphate (ADP) in patients with coronary artery disease treated with dual antiplatelet therapy has not been previously examined. Samples from 96 patients with established coronary artery disease treated with aspirin and clopidogrel were examined. Platelet aggregation was performed by light transmittance aggregometry in platelet-rich plasma (PRP), with platelet-poor plasma (PPP) as reference, and ADP 5 µM as agonist. Kaolin-activated thrombelastography (TEG) was performed in citrate PPP. PRP after aggregation was centrifuged and plasma supernatant (PSN) collected. FXIIIa was measured in PPP and PSN. Platelet aggregation after stimulation with ADP 5 µM resulted in 24% additional FXIIIa release in PSN as compared to PPP (99.3 ± 27 vs. 80.3 ± 24%, p < 0.0001). FXIIIa concentration in PSN correlated with maximal plasma clot strength (TEG-G) (r = 0.48, p < 0.0001), but not in PPP (r = 0.15, p = 0.14). Increasing quartiles of platelet-derived FXIIIa were associated with incrementally higher TEG-G (p = 0.012). FXIIIa release was similar between clopidogrel responders and non-responders (p = 0.18). In summary, platelets treated with aspirin and clopidogrel release a significant amount of FXIIIa upon aggregation by ADP. Platelet-derived FXIIIa may contribute to differences in plasma TEG-G, and thus, in part, provide a mechanistic explanation for high clot strength observed as a consequence of platelet activation. Variability in clopidogrel response does not significantly influence FXIIIa release from platelets.
Asunto(s)
Plaquetas/inmunología , Enfermedad de la Arteria Coronaria/tratamiento farmacológico , Factor XIIIa/inmunología , Inhibidores de Agregación Plaquetaria/uso terapéutico , Agregación Plaquetaria/efectos de los fármacos , Tromboelastografía/métodos , Ticlopidina/análogos & derivados , Clopidogrel , Femenino , Humanos , Masculino , Persona de Mediana Edad , Inhibidores de Agregación Plaquetaria/administración & dosificación , Ticlopidina/administración & dosificación , Ticlopidina/uso terapéuticoRESUMEN
Factor XIII (FXIII) is necessary for cross linking of fibrin strands and generation of stable fibrin clot. FXIII Val34Leu is a common genetic single nucleotide polymorphism that has been associated with accelerated fibrin stabilization and reduced rate of fibrinolysis. The contribution of Val34Leu to long term risk of recurrent myocardial infarction (MI) in patients with coronary stenting has not been conclusively established. The objective of the study was to examine the effects of Val34Leu on fibrin generation, platelet aggregation, and long term clinical outcomes in patients with coronary artery disease treated with dual antiplatelet therapy. Patients with angiographically documented coronary artery disease who were treated with aspirin and clopidogrel were enrolled (n = 211). Light transmittance aggregometry and plasma fibrin clot formation using thrombelastography (TEG) were determined. Genotyping of Val34Leu was performed using Taqman assay. Clinical events during follow up were recorded. Homozygous carriers of 34 Leu variant had significantly shorter fibrin clot formation time as compared to wild type individuals (TEG K: 1.27 ± 0.3 vs. 1.68 ± 1.1 min, p = 0.011). The Val34Leu variant was associated with gene dose dependent increased risk of MI (log rank, p = 0.002) or occurrence of composite of MI and CV death (log rank, p = 0.005) with highest event rates observed in homozygous carriers of 34 Leu. In summary, FXIII Val34Leu polymorphism was associated with increased rate of fibrin stabilization in homozygous carriers of the variant and may increase risk of recurrent MI and death in patients with angiographically established coronary artery disease treated with dual antiplatelet therapy.
Asunto(s)
Enfermedad de la Arteria Coronaria , Factor XIII , Infarto del Miocardio , Polimorfismo Genético , Adulto , Anciano , Sustitución de Aminoácidos , Aspirina/administración & dosificación , Clopidogrel , Enfermedad de la Arteria Coronaria/sangre , Enfermedad de la Arteria Coronaria/complicaciones , Enfermedad de la Arteria Coronaria/tratamiento farmacológico , Enfermedad de la Arteria Coronaria/genética , Factor XIII/genética , Factor XIII/metabolismo , Femenino , Fibrina/genética , Fibrina/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/sangre , Infarto del Miocardio/tratamiento farmacológico , Infarto del Miocardio/etiología , Infarto del Miocardio/genética , Agregación Plaquetaria/efectos de los fármacos , Agregación Plaquetaria/genética , Inhibidores de Agregación Plaquetaria/administración & dosificación , Tromboelastografía , Ticlopidina/administración & dosificación , Ticlopidina/análogos & derivadosRESUMEN
Recent candidate gene studies using a human liver bank and in vivo validation in healthy volunteers identified polymorphisms in cytochrome P450 (CYP) 3A4 gene (CYP3A4*22), Ah-receptor nuclear translocator (ARNT), and peroxisome proliferator-activated receptor-α (PPAR-α) genes that are associated with the CYP3A4 phenotype. We hypothesized that the variants identified in these genes may be associated with altered clopidogrel response, since generation of clopidogrel active metabolite is, partially mediated by CYP3A activity. Blood samples from 211 subjects, of mixed racial background, with established coronary artery disease, who had received clopidogrel, were analyzed. Platelet aggregation was determined using light transmittance aggregometry (LTA). Genotyping for CYP2C19*2, CYP3A4*22, PPAR-α (rs4253728, rs4823613), and ARNT (rs2134688) variant alleles was performed using Taqman® assays. CYP2C19*2 genotype was associated with increased on-treatment platelet aggregation (adenosine diphosphate 20 µM; P=0.025). No significant difference in on-treatment platelet aggregation, as measured by LTA during therapy with clopidogrel, was demonstrated among the different genotypes of CYP3A4*22, PPAR-α, and ARNT. These findings suggest that clopidogrel platelet inhibition is not influenced by the genetic variants that have previously been associated with reduced CYP3A4 activity.
RESUMEN
INTRODUCTION: Treatment with clopidogrel, a selective platelet P2Y12 receptor antagonist, reduces risk of recurrent ischemic events in patients with acute coronary syndrome (ACS), by limiting platelet aggregation and activation. Stable whole blood clot formation requires activation of platelets, generation of fibrin and final fibrin crosslinks. In this study we intended to compare plasma and whole blood thrombelastography (TEG) measurements in patients during ACS. MATERIALS AND METHODS: Whole blood and plasma samples from 32 patients with non-ST segment elevation myocardial infarction (NSTEMI) were collected after administration of clopidogrel. Whole blood and plasma fibrin clot strength (MA) were determined by TEG. Platelet aggregation was determined by light transmittance aggregometry (LTA) using adenosine 5'-diphosphate (ADP), thrombin receptor activation peptide (TRAP), or collagen as agonists. Fibrinogen and C-reactive protein (CRP) concentrations were measured by ELISA. RESULTS: Heightened plasma fibrin clot strength was associated with increased platelet reactivity stimulated by ADP (ρ=0.536; p=0.002), TRAP (ρ=0.481; p=0.007), and collagen (ρ=0.538; p=0.01). In contrast to plasma fibrin MA, whole blood MA did not correlate with platelet aggregation. Platelet count was the primary contributor to the difference in thrombin induced whole blood MA and plasma fibrin MA. Increasing levels of CRP were associated with increased plasma fibrin clot strength and platelet reactivity. CONCLUSIONS: Our data suggest that inflammation is associated with increased plasma fibrin clot strength and lower platelet inhibition by clopidogrel during ACS. Platelet count is a main contributor to additional contractile force of whole blood TEG as compared to plasma TEG during treatment with clopidogrel.
Asunto(s)
Síndrome Coronario Agudo/sangre , Síndrome Coronario Agudo/tratamiento farmacológico , Fibrinógeno/metabolismo , Inhibidores de Agregación Plaquetaria/uso terapéutico , Ticlopidina/análogos & derivados , Síndrome Coronario Agudo/patología , Proteína C-Reactiva/metabolismo , Clopidogrel , Femenino , Humanos , Masculino , Persona de Mediana Edad , Agregación Plaquetaria/efectos de los fármacos , Pruebas de Función Plaquetaria , Tromboelastografía/métodos , Ticlopidina/uso terapéuticoRESUMEN
Inflammation is implicated in the progression of coronary artery disease and the molecular processes of inflammation and thrombosis are closely intertwined. Elevated levels of C-reactive protein (CRP) have been associated with an elevated risk of adverse ischaemic events after coronary stenting and hypercoagulability. Heightened whole blood clot strength measured by thrombelastography (TEG) has been associated with adverse ischaemic events after stenting. We intended to examine the relationship of CRP to plasma fibrin clot strength in patients after coronary stenting. Plasma fibrin clot strength was measured by TEG in 54 patients 16-24âh after undergoing elective percutaneous coronary intervention (PCI). Coagulation was induced in citrated plasma by addition of kaolin and CaCl2. Plasma levels of CRP and fibrinogen were measured by enzyme-linked immunoassay. Increasing quartiles of CRP were associated with increasing levels of maximal plasma fibrin clot strength measured by TEG (Pâ<â0.001) and increasing BMI (Pâ=â0.04). Patients in the highest quartile of CRP had significantly higher maximal fibrin clot strength (G) than the patients in the lowest quartile (G: 3438â±â623 vs. 2184â±â576âdyn/cm, Pâ<â0.0001). Fibrinogen concentration was not significantly different across quartiles of CRP (Pâ=â0.97). Patients with established coronary artery disease undergoing coronary stenting who have elevated CRP after PCI exhibit heightened maximal plasma fibrin clot strength as compared with those with low CRP. Thrombotic risk associated with elevated CRP may be linked to procoagulant changes and high tensile fibrin clot strength independent of fibrinogen concentration.
Asunto(s)
Angioplastia Coronaria con Balón , Proteína C-Reactiva/metabolismo , Enfermedad de la Arteria Coronaria/sangre , Fibrina/metabolismo , Trombofilia/sangre , Trombosis/sangre , Anciano , Coagulación Sanguínea , Cloruro de Calcio/química , Enfermedad de la Arteria Coronaria/complicaciones , Enfermedad de la Arteria Coronaria/patología , Enfermedad de la Arteria Coronaria/cirugía , Femenino , Fibrinógeno/metabolismo , Humanos , Inflamación , Caolín/química , Masculino , Persona de Mediana Edad , Factores de Riesgo , Stents , Tromboelastografía , Trombofilia/complicaciones , Trombofilia/patología , Trombofilia/cirugía , Trombosis/complicaciones , Trombosis/patología , Trombosis/cirugíaRESUMEN
INTRODUCTION: Clopidogrel inhibits ADP mediated platelet aggregation through inhibition of the P2Y12 receptor by its active metabolite. Thrombin induces platelet aggregation by binding to protease activated receptor-1 (PAR-1), and inhibition of PAR-1 has been evaluated in patients treated with clopidogrel to reduce ischemic events after acute coronary syndromes. Residual PAR-1 mediated platelet aggregation may be dependent on extent of clopidogrel response. MATERIAL AND METHODS: Platelet aggregation was measured in 55 patients undergoing elective PCI at 16-24 hours after 600 mg clopidogrel loading dose by light transmittance aggregometry using ADP 20 µM and thrombin receptor agonist peptide (TRAP) at 15 µM and 25 µM as agonists. Genomic DNA was genotyped for common CYP2C19 variants. RESULTS: Increasing quartiles of 20 µM ADP induced platelet aggregation after clopidogrel loading were associated with increasing levels of TRAP mediated platelet aggregation. Patients in the highest quartile (clopidogrel non-responders) of post treatment ADP aggregation had significantly higher TRAP mediated aggregation than the patients in the lowest quartile (clopidogrel responders) [TRAP 15 µM: 79.6 ± 5% vs. 69.5 ± 8%, p<0.001]. CONCLUSIONS: Non-responders to clopidogrel show increased residual platelet aggregation induced by TRAP, whereas clopidogrel responders exhibit attenuated response to TRAP. Addition of PAR-1 antiplatelet drugs may be most effective in patients with reduced clopidogrel response and high residual TRAP mediated platelet aggregation.
Asunto(s)
Plaquetas/efectos de los fármacos , Intervención Coronaria Percutánea , Inhibidores de Agregación Plaquetaria/uso terapéutico , Agregación Plaquetaria/efectos de los fármacos , Receptor PAR-1/metabolismo , Ticlopidina/análogos & derivados , Anciano , Hidrocarburo de Aril Hidroxilasas/genética , Plaquetas/citología , Clopidogrel , Citocromo P-450 CYP2C19 , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Intervención Coronaria Percutánea/efectos adversos , Inhibidores de Agregación Plaquetaria/farmacología , Receptores de Trombina/metabolismo , Trombosis/prevención & control , Ticlopidina/farmacología , Ticlopidina/uso terapéuticoRESUMEN
Beta1-containing adhesions at the plasma membrane function as dynamic complexes to provide bidirectional communication between the cell and its environment, yet commonly are used by pathogens to gain host cell entry. Recently, the cholesterol-lowering drug simvastatin was found to inhibit host invasion through beta1-containing adhesion complexes. To better understand the regulatory mechanisms controlling adhesion formation and uptake and the use of these complexes by Staphylococcus aureus, the primary etiologic agent in sepsis, bacteremia and endocarditis, we investigated the mechanism of inhibition by simvastatin. In response to simvastatin, adhesion complexes diminished as well as beta1 trafficking to the plasma membrane required to initiate adhesion formation. Simvastatin stimulated CDC42 activation and coupling to p85, a small-guanosine triphosphatase (GTPase) activating protein (GAP), yet sequestered CDC42 coupled to p85 within the cytosol. Loss of p85 GAP activity through use of genetic strategies decreased host cell invasion as well as beta1 trafficking. From these findings, we propose a mechanism whereby p85 GAP activity localized within membrane compartments facilitates beta1 trafficking. By sequestering p85 within the cytosol, simvastatin restricts the availability and uptake of the receptor used by pathogenic strains to gain host cell entry.