On-Treatment Platelet Reactivity is a Predictor of Adverse Events in Peripheral Artery Disease Patients Undergoing Percutaneous Angioplasty.

OBJECTIVES: Few data are available on the association between a different entity of platelet inhibition on antiplatelet treatment and clinical outcomes in patients with peripheral artery disease (PAD). The aim of this study was to evaluate the degree of on-treatment platelet reactivity, and its association with ischaemic and haemorrhagic adverse events at follow up in PAD patients undergoing percutaneous transluminal angioplasty (PTA). METHODS: In this observational, prospective, single centre study, 177 consecutive patients with PAD undergoing PTA were enrolled, and treated with dual antiplatelet therapy with aspirin and a P2Y12 inhibitor. Platelet function was assessed on blood samples obtained within 24 h from PTA by light transmission aggregometry (LTA) using arachidonic acid (AA) and adenosine diphosphate (ADP) as agonists of platelet aggregation. High on-treatment platelet reactivity (HPR) was defined by LTA ≥ 20% if induced by AA, and LTA ≥ 70% if induced by ADP. Follow up was performed to record outcomes (death, major amputation, target vessel re-intervention, acute myocardial infarction and/or myocardial revascularisation, stroke/TIA, and bleeding). RESULTS: HPR by AA and HPR by ADP were found in 45% and 32% of patients, respectively. During follow up (median duration 23 months) 23 deaths (13%) were recorded; 27 patients (17.5%) underwent target limb revascularisation (TLR), two (1.3%) amputation, and six (3.9%) myocardial revascularisation. Twenty-four patients (15.6%) experienced minor bleeding. On multivariable analysis, HPR by AA and HPR by ADP were independent predictors of death [HR 3.8 (1.2-11.7), p = .023 and HR 4.8 (1.6-14.5), p = .006, respectively]. The median value of LTA by ADP was significantly lower in patients with bleeding complications than in those without [26.5% (22-39.2) vs. 62% (44.5-74), p < .001). LTA by ADP ≤ 41% was independently associated with bleeding HR 14.6 (2.6-24.0), p = .001] on multivariable analysis. CONCLUSIONS: In this study a high prevalence of on-clopidogrel and aspirin high platelet reactivity was found, which was significantly associated with the risk of death. Conversely, a low on-clopidogrel platelet reactivity was associated with a higher risk of bleeding. These results document that the entity of platelet inhibition is associated with both thrombotic and bleeding complications in PAD patients.

Residual platelet reactivity to predict long-term clinical outcomes after clopidogrel loading in patients with acute coronary syndromes: comparison of different cutoff values by light transmission aggregometry from the responsiveness to clopidogrel and stent thrombosis 2-acute coronary syndrome (RECLOSE 2-ACS) study.

The aim of this study was the identification of the optimal cutoff value of high residual platelet reactivity (HRPR) assessed by light transmission aggregometry (LTA) in the responsiveness to clopidogrel and stent thrombosis 2-acute coronary syndrome (RECLOSE 2-ACS) patient cohort to discriminate patients with and without major adverse cardiac events (MACE) and cardiac death at 2 years. The RECLOSE 2-ACS study included 1,789 patients with ACS who underwent LTA after clopidogrel loading. A post hoc cutoff value for HRPR was defined with the ROC curve and the Youden index and compared with the protocol-defined cutoff of 70 %. By ROC analysis, 63 % resulted the optimal cutoff value to predict both MACE and cardiac death at 2 years follow-up. A significant sensitivity improvement for the ROC-based cutoff value was noted (p < 0.001), at the price of lower specificity and predictive accuracy. The latter were 81 % for MACE and 85 % for cardiac death with the 70 % cutoff, while the respective figures were 73 and 75 % with the 63 % cutoff. The areas under the curve were virtually identical with the 70 and 63 % cutoffs both for MACE (0.71) and cardiac death (0.79). A residual platelet reactivity cutoff of 70 % by LTA, compared to the ROC-based cutoff of 63 %, allows for the identification of a subset of patients at very high risk of adverse ischemic events, making LTA-ADP test more acceptable in clinical practice for the identification of subjects at risk than other platelet function assays with broader definitions of HRPR.

Perioperative assessment of platelet function by Thromboelastograph Platelet Mapping in cardiovascular patients undergoing non-cardiac surgery.

UNLABELLED: Five percent of patients on dual antiplatelet therapy after coronary artery stent implantation will need non-cardiac surgery within the first year of therapy, and many more will need surgery later on. A function assay that evaluates platelet reactivity and inhibition by drug therapy is beneficial for such patients. Platelet Mapping assay (PM) using the TEG analyzer was tested in surgical patients. After IRB approval, 60 patients on combined aspirin and clopidogrel therapy were consented and enrolled. The TEG maximal amplitude (MA) and the percentage (%) platelet inhibition were recorded and analyzed. Fifty-seven patients (mean age 65.7 ± 10.9 years) had preoperative data only. Distribution of preoperative ADP (43.6 ± 24.4%) and AA inhibition (52.8 ± 30.2%) was determined, as well as for the preoperative MA ADP (43.1 ± 15.9 mm) and MA AA (37.2 ± 19.6 mm), showing an offset of the effect of both medications starting from day 3. Patients with complete pre- and postoperative data were stratified depending on duration off antiplatelet therapy (≤3 days, 3-7 days and >7 days): n = 27, ADP % preop inhibition (43.2 ± 21.6%), ADP % postop inhibition (32.3 ± 18.3%), p = 0.048. Distribution of immediate pre- and post- ADP and AA % inhibitions, showing a possible reduction in Δ of inhibition for clopidogrel at 3 days, were also assessed. CONCLUSION: According to the findings, the TEG PM assay might be a feasible approach to objectively evaluate the effects of aspirin and clopidogrel during the perioperative period and potentially guide drug management.

High on-treatment platelet reactivity by ADP and increased risk of MACE in good clopidogrel metabolizers.

High on-treatment platelet reactivity (HPR) by ADP, which primarily reflects the effect of thienopyridines, has been found to be an independent predictor of ischemic events in patients with acute coronary syndrome (ACS) on dual antiplatelet therapy. CYP2C19*2 is associated with HPR by ADP. The aim of our study was to evaluate if high on-clopidogrel platelet reactivity (HPR) by ADP is associated with an increased risk of major adverse coronary events (MACE) after ACS independent of CYP2C19*2 allele, i.e. whether genotyping patients for CYP2C19*2 polymorphism is sufficient to identify those to be switched to novel antiplatelets. A total of 1187 patients were included (CYP2C19 *1/*1 n = 892; *1/*2 n = 264; *2/*2 n = 31); 76 MACE (CV death and non-fatal MI) were recorded in non-carriers of CYP2C19*2 (8.5%) and 39 in carriers of CYP2C19*2 (13.2%). At the landmark analysis in the first 6 months, HPR by ADP and CYP2C19*2 allele were both significantly and independently associated with MACE [HPR by ADP: HR = 2.0 (95% CI 1.2-3.4), p = 0.01; CYP2C19*2 allele: HR = 2.3 (95% CI 1.3-3.9), p = 0.003]. At the land mark analysis from 7 to 12 months, only HPR by ADP remained significantly associated with the risk of MACE [HPR by ADP: HR = 2.7 (95% CI 1.4-5.3), p = 0.003; CYP2C19*2: HR = 0.8 (95% CI 0.2-1.1), p = ns]. CYP2C19*2 allele and HPR by ADP are both independently associated with an increased risk of MACE in the first 6 months after ACS. HPR by ADP is associated with an increased risk until 12 months of follow-up. Therefore, both phenotype and genotype are clinically relevant for the evaluation of the antiplatelet effect of clopidogrel and for the prognostic stratification of ACS patients.

Rotational thromboelastometry for diagnosis of fibrinolysis induced by urokinase in an in-vitro model.

Fibrinolysis can be abnormally activated in several critical care settings but it's often misdiagnosed by standard laboratory tests. Although rotational thromboelastometry can assess the whole coagulative process, its ability to detect fibrinolysis has been questioned. Aim of this study was to investigate the ability of thromboelastometry in detecting induced fibrinolysis in an in-vitro model. Whole blood samples were taken from 18 healthy volunteers. Each sample was split and added with increasing urokinase concentrations till to reach 0, 50, 75 and 100 IU/ml. Thromboelastometry tests, extem and aptem, were performed on the obtained samples. If significant lysis at 50 IU/ml was recorded, also 10, 25 and 35 IU/ml drug concentrations were tested. No lytic effects were detected in 10 IU/ml samples. Lysis variables were the most sensitive in detecting fibrinolysis even at 25 IU/ml (P < 0.05). Clot firmness parameters were also affected by urokinase, but only at the two highest drug concentrations (P < 0.05). Extem/aptem ratio enhanced the sensitivity of these parameters only if lysis was more marked. Analysing groups of different lysis severity, the time to achieve maximum clot firmness could anticipate an ongoing fulminant or intermediate lysis with 100% sensitivity and 100% specificity (P < 0.05) when lower than 1341.5 s. Rotational thromboelastometry could detect fibrinolysis when it was induced in vitro by 25 IU/ml urokinase or more. Apart from the parameters specific for lysis, time to achieve maximum clot firmness appeared as the earliest indicator of fibrinolysis with high sensitivity and specificity especially if a more intense lysis was going on.

Light transmittance aggregometry induced by different concentrations of adenosine diphosphate to monitor clopidogrel therapy: a methodological study.

Light transmission aggregation (LTA) is considered the reference method to identify residual platelet reactivity (RPR) in high-risk patients with coronary artery disease on clopidogrel treatment. An international standardization of this technique is still ongoing and different concentrations of adenosine diphosphate (ADP) as the agonist for LTA have been used to evaluate the inhibitory effect of clopidogrel treatment. To evaluate RPR, LTA was performed using different ADP concentrations (2, 5, 10, and 20 µmol/L) in 466 high-risk patients with coronary artery disease on dual antiplatelet therapy who underwent percutaneous coronary intervention and in 46 healthy subjects. A VerifyNow P2Y12 assay was assessed as a point-of care system. Imprecision studies showed higher coefficients of variation for LTA by 2 and 5 µmol/L ADP (healthy subjects: 4.7% and 3.9%; patients: 6.8% and 5.2%, respectively) in comparison with those obtained determining LTA using 10 and 20 µmol/L ADP (healthy subjects: 2.2% and 2.3%; patients: 2.7% and 3.1%, respectively). In patients, a significant difference (P < 0.0001) between mean values of LTA obtained with all ADP concentrations was found, even if LTA data were significantly correlated (at least: rho = 0.88, P < 0.0001). However, data from 10 and 20 µmol/L ADP LTA were very similar and highly concordant (k = 95.9%). All agreements were significant (for all P < 0.0001), in particular the agreement between 10 and 20 µmol/L ADP LTA was very good (k = 0.86, P < 0.0001). A moderate agreement between VerifyNow and both 10 and 20 µmol/L ADP LTA was observed. LTA by 10 and 20 µmol/L ADP gave equivalent percentages of aggregation and highly concordant results in terms of RPR in patients with coronary artery disease on clopidogrel. Significant concordant results were observed between both 10 and 20 µM ADP LTA and VerifyNow. This suggests that a concentration of 10 µmol/L ADP may be considered adequate for the identification of RPR of patients on clopidogrel and should be preferred for standardization LTA.

Impact of cardiovascular burden on coagulation pathway in apparently healthy women planning oocyte donation.

BACKGROUND: Hormonal fertility treatments are associated with increased coagulation factors inducing procoagulant milieu and possibly thrombotic risk. OBJECTIVE: To assess coagulation by ROTEM and coagulation tests in apparently healthy infertile women before oocyte donation procedure. METHODS: We enrolled 51 women (Assisted Reproductive Technology Centre, Florence). ROTEM and coagulation parameters were assessed before the start of infertility treatment. RESULTS: We divided women in 3 groups according to the number of cardiovascular risk factors: Group A (n = 10), Group B (n = 16), and Group C (n = 25). By considering ROTEM Extem test, a significantly increased of MCF, TPI, and G were observed in groups B (p = 0.005, p = 0.03, and p = 0.007) and C (p = 0.01, p = 0.05, and p = 0.005) in comparison to group A. As regards ROTEM Intem test, the TPI and G values were significantly higher in groups B and C in comparison to group A (p < 0.01). MCF by Fibtem test significantly increased in groups B and C than in group A (p = 0.004 and p = 0.002, respectively). FVIII, vWF:Ag and D-dimer values significantly increase according to the presence of≥2 risk factors. CONCLUSIONS: Data from coagulative assessment permit to sensitively identify women with potentially procoagulable state, which represents a risk factor of thromboembolic event during hormone treatment.

Cardiovascular death and nonfatal myocardial infarction in acute coronary syndrome patients receiving coronary stenting are predicted by residual platelet reactivity to ADP detected by a point-of-care assay: a 12-month follow-up.

BACKGROUND: The clinical impact of platelet aggregation assessed by point-of-care assays is unknown. We sought to evaluate whether high residual platelet reactivity (RPR) to ADP during clopidogrel therapy, measured by a point-of-care assay, predicts adverse clinical events in acute coronary syndrome patients undergoing percutaneous coronary intervention. METHODS AND RESULTS: We used the VerifyNow P2Y12 assay (Accumetrics Inc, San Diego, Calif) to determine RPR to ADP in 683 patients with acute coronary syndrome undergoing dual-antiplatelet therapy who underwent percutaneous coronary intervention with bare-metal or drug-eluting stent implantation. All patients received a single 600-mg clopidogrel loading dose followed by 75 mg of clopidogrel daily and 100 to 325 mg of aspirin daily. The end points of the study at follow-up of 12 months were cardiovascular death, nonfatal myocardial infarction (MI), and target-vessel revascularization. At a 12-month follow-up, we found 51 ischemic events (24 cardiovascular deaths [3.5%], 27 nonfatal MIs [3.9%]) and 40 target-vessel revascularizations (5.8%). By receiver operating characteristic curve (ROC) analysis, the optimal cutoff value in predicting 12-month cardiovascular death and nonfatal MI was P2Y12 reaction unit values > or =240. RPR, defined in the presence of P2Y12 reaction unit values above this cutoff, was found to be a significant and independent predictor of cardiovascular death and nonfatal MI in a model that adjusted for cardiovascular risk factors, renal failure, reduced left ventricular ejection fraction, multivessel disease, total stent length, bifurcation lesions, number of lesions treated, type of stent, and use of glycoprotein IIb/IIIa inhibitors (cardiovascular death: hazard ratio 2.55, 95% CI 1.08 to 6.07, P=0.034; nonfatal MI: hazard ratio 3.36, 95% CI 1.49 to 7.58, P=0.004). No significant association was found between high RPR and the risk of target-vessel revascularization. CONCLUSIONS: RPR to ADP with clopidogrel therapy, measured by the point-of-care assay VerifyNow P2Y12, is able to detect acute coronary syndrome patients at risk of 12-month cardiovascular death and nonfatal MI. The optimal cutoff value was identified as being 240 P2Y12 reaction units.

Platelet Reactivity in Hepatitis C Virus-Infected Patients on Dual Antiplatelet Therapy for Acute Coronary Syndrome.

Background Coronary artery disease (CAD) has been recognized as a serious and potentially life-threatening complication of Hepatitis C Virus (HCV) infection. High on-treatment platelet reactivity has been associated with high risk of ischemic events in patients with CAD, but data regarding the association with HCV infection are still lacking. This post hoc analysis aims to assess high on-treatment platelet reactivity, severity of CAD, and long-term outcomes of patients with acute coronary syndrome (ACS) who were infected with HCV. Methods and Results Patients with ACS who were infected with HCV (n=47) were matched to patients with ACS and without HCV (n=137) for age, sex, diabetes mellitus, hypertension, and renal function. HCV-infected patients with ACS had higher levels of platelet reactivity (ADP10-light transmittance aggregometry, 56±18% versus 44±22% [P=0.002]; arachidonic acid-light transmittance aggregometry, 25±21% versus 16±15% [P=0.011]) and higher rates of high on-treatment platelet reactivity on clopidogrel and aspirin compared with patients without HCV. Moreover, HCV-infected patients with ACS had higher rates of multivessel disease (53% versus 30%; P=0.004) and 3-vessel disease (32% versus 7%; P<0.001) compared with patients without HCV. At long-term follow-up, estimated rates of major adverse cardiovascular events (cardiac death, nonfatal myocardial infarction, and ischemia-driven revascularization) were 57% versus 34% (P=0.005) in HCV- and non-HCV-infected patients with ACS, respectively. In addition, thrombolysis In Myocardial Infarction (TIMI) major bleeding rates were higher in HCV-infected patients (11% versus 3%; P=0.043) compared with noninfected patients. Multivariable analysis demonstrated that HCV infection was an independent predictor of high on-treatment platelet reactivity, severity of CAD, and long-term outcome. Conclusions In this hypothesis-generating study, patients with ACS and HCV infection showed increased on-treatment platelet reactivity, more severe CAD, and worse prognosis compared with patients without HCV.

Clinical Implications of "Tailored" Antiplatelet Therapy in Patients With Chronic Total Occlusion.

Background Clopidogrel nonresponsiveness is a prognostic marker after percutaneous coronary intervention. Prasugrel and ticagrelor provide a better platelet inhibition and represent the first-line antiplatelet treatment in acute coronary syndrome. We sought to assess the prognostic impact of high platelet reactivity (HPR) and the potential clinical benefit of a "tailored" escalated or changed antiplatelet therapy in patients with chronic total occlusion. Methods and Results From Florence CTO-PCI (chronic total occlusion-percutaneous coronary intervention) registry, platelet function assessed by light transmission aggregometry, was available for 1101 patients. HPR was defined by adenosine diphosphate test ≥70% and optimal platelet reactivity by adenosine diphosphate test <70%. The endpoint of the study was long-term cardiac survival. Patients were stratified according to light transmission aggregometry results: optimal platelet reactivity (82%) and HPR (18%). Means for the adenosine diphosphate test were 44±16% versus 77±6%, respectively. Three-year survival was significantly higher in the optimal platelet reactivity group compared with HPR patients (95.3±0.8% versus 86.2±2.8%; P<0.001). With the availability of new P2Y12 inhibitors, a deeper platelet inhibition (46±17%) and similar survival to the optimal platelet reactivity group were achieved in patients with HPR on clopidogrel therapy after escalation. Conversely, HPR on clopidogrel therapy "not switched" was associated with cardiac mortality (hazard ratio 2.37; P=0.003) after multivariable adjustment. Conclusions HPR on treatment could be a modifiable prognostic marker by new antiaggregants providing a deeper platelet inhibition associated with clinical outcome improvement in complex chronic total occlusion patients. A "tailored" antiplatelet therapy, also driven by the entity of platelet inhibition, could be useful in these high risk setting patients.

eNOS gene influences platelet phenotype in acute coronary syndrome patients on dual antiplatelet treatment.

Nitric Oxide (NO) plays a relevant role in regulating platelet recruitment and eNOS is the major isoform known to be expressed in platelets. Polymorphisms in the eNOS gene with a reduced NO availability might affect platelet phenotype. The aim of our study was to evaluate the role of eNOS-786T > C, 894G > T and 4a/4b polymorphisms in modulating platelet phenotype in 1442 acute coronary syndrome (ACS) patients on dual antiplatelet therapy, previously investigated in relation to platelet function. Platelet aggregation on platelet-rich plasma after collagen (2 microg/mL), ADP (10 microM) and arachidonic acid (AA) (1 mM) stimuli and the genetic analysis of eNOS polymorphisms were assessed. In subjects carrying the eNOS 4a and -786C alleles a significantly higher maximal platelet aggregation value after AA was found (p = 0.02 and p = 0.047, respectively). eNOS 4a but not -786C allele weakly influenced platelet aggregation after collagen stimulus (p = 0.05). eNOS 4a allele significantly and independently influenced AA-induced platelet aggregation (p = 0.01). A significantly higher percentage of patients with AA-induced high residual platelet reactivity (RPR) was found in subjects carrying both eNOS 4a and -786C allele (p = 0.03 and p = 0.04, respectively). At logistic multivariate analysis, the eNOS 4a allele significantly influenced the AA-induced high residual platelet reactivity (p = 0.02). This study evidences a role for eNOS gene in moderately, but significantly, modulating platelet phenotype in a high-risk population on dual antiplatelet treatment.

Lipid, inflammatory and haemorheological profiles are significantly affected by farmed fish eating: an intervention study.

AIM: The objective of the present study was to evaluate the influence of short-term dietary intake of farmed fish on biomarkers related to the atherosclerotic process. METHODS AND RESULTS: Lipid, inflammatory, and haemorheological variables before (T0) and after a dietary intervention with about 800 g Orbetello farmed sea bass per week for 10 weeks (T1) were evaluated in nine dyslipidemic subjects. Fish intake significantly decreased triacylglycerols (T1, 140.2+/-20.3 mg/dl versus T0, 183.3+/-29.2 mg/dl; P =0.04), whereas no significant changes for the other lipid variables have been observed. Moreover, dietary intervention significantly (P <0.05) decreased all of the inflammatory parameters investigated; namely, high-sensitivity C-reactive protein, interleukin-6, and interleukin-8. Furthermore, a significant (P =0.04) improvement in erythrocytes' deformability index was reported after 10 weeks of fish dietary intake (9.0+/-0.7% versus 5.4+/-1.0% for T1 and T0, respectively). CONCLUSION: Dietary short-term intake of farmed fish seems to impose favourable biochemical changes in dyslipidemic subjects.

Patient blood management in cardiac surgery: The "Granducato algorithm".

BACKGROUND: Patients undergoing cardiac surgery are subject to severe alterations of the coagulation system. The four cardiac surgery centers in Tuscany (Italy) structured and shared an algorithm (Granducato Patient Blood Management algorithm, G-PBMa) with predefined interventions for patient blood management. The aim of the study is to analyze the impact of that algorithm on the transfusion needs and bleeding-related outcomes in a large patient population. METHODS: Multicenter retrospective observational study on 3839 patients undergoing cardiac surgery at the four cardiac centers in Tuscany. The G-PBMa was released at the end of 2015 and it was structured in three parts: pre-, intra-, and post-operative. The year 2014, before the G-PBMa (1955 patients) and the year 2016 (1884 patients) after the G-PBMa in place were compared. Logistic regression analyses were used. RESULTS: The main changes introduced were the routine application of viscoelastic tests in bleeding patients (+72%) and the use of fibrinogen and prothrombin complex concentrate (+67%). The G-PBMa resulted in a significant reduction in the overall transfusion rate and in the transfusion rate of the separate blood products (relative risk for transfusions: 0.75, 95% confidence interval 0.65-0.85, P = 0.001). For preoperative hemoglobin values of between 8 and 10 g/dL, the absolute difference in RBC transfusion rate before and after the G-PBMa introduction ranged around 15%-17%. The G-PBMa introduction determined lower (P = 0.02) chest drain blood loss, lower (P = 0.001) postoperative acute kidney injury and shorter (P = 0.001) hospital stay. CONCLUSIONS: The G-PBMa was effective in reducing blood loss, transfusion requirements, and resulted in a better outcome.

Relationship between high platelet turnover and platelet function in high-risk patients with coronary artery disease on dual antiplatelet therapy.

A high platelet turnover rate produce a population of immature reticulated platelets (RP) that could confer, despite of antiplatelet drugs, a residual platelet reactivity (RPR) in coronary artery disease (CAD) patients. To assess the influence of RP on platelet reactivity in CAD patients on dual antiplatelet therapy we measured RP in 372 patients by using the Sysmex XE-2100 haematology analyzer and platelet function by optical platelet aggregometry (PA) on platelet-rich-plasma induced by 1 mmol arachidonic acid (AA-PA) and 10 microM ADP (ADP-PA). RPR was defined as either AA-PA>20% or ADP-PA>70%. RP were expressed as a percentage of RP of the total optical platelet count (immature platelet fraction; IPF) and as the percentage of RP highly fluorescent (highly fluorescent immature platelet fraction; H-IPF). Moderate but significant positive correlations between PA, IPF, H-IPF, and mean platelet volume (MPV) were found. According to tertiles of IPF, H-IPF and MPV, a significant trend for an increase of platelet aggregation by AA and ADP was evidenced. Furthermore, a significant difference for IPF, H-IPF and MPV between patients with and without RPR was observed. A linear regression analysis showed that IPF, H-IPF and MPV significantly affected PA measured by AA and ADP. At multivariate linear regression analysis these associations were confirmed. Moreover, a logistic regression analysis demonstrated that IPF, H-IPF and MPV significantly influenced the risk of RPR, and in the multivariate model these results remained significant. This study indicates that a high rate of platelet turnover is a new mechanism associated with platelet reactivity in high risk CAD patients on dual antiplatelet therapy.

Thrombotic events in high risk patients are predicted by evaluating different pathways of platelet function.

A higher rate of clinical events in poor clopidogrel and/or aspirin responders was documented by using different methods to measure platelet function, but no conclusive data about the appropriate methodology to explore platelet reactivity are available. A total of 746 patients included in the cohort of the RECLOSE trial who had successful drug-eluting stent implantation were assessed for post-treatment residual platelet reactivity (RPR) in platelet-rich plasma by 10 microM adenosine 5'-diphosphate (ADP), 1 mM arachidonic acid (AA) and 2 microg/ml collagen-induced platelet aggregation and in whole blood by the PFA-100 system. At six-month follow-up, RPR by two stimuli (ADP and AA or ADP and collagen) and by three stimuli (ADP, AA and collagen) is significantly associated with higher percentage of primary (definite or probable stent thrombosis) and secondary (cardiac mortality and stent thrombosis) end-points than RPR by ADP, AA, collagen and PFA-100 system. According to the primary and secondary end points, the specificity values for RPR identified by two (ADP and AA:94%; ADP and collagen:97%) and three stimuli were higher with respect to RPR by ADP (88%), or RPR by AA (83%) or RPR by collagen (90%). The positive likelihood ratio values of RPR by three stimuli (9.55) or of RPR by ADP and collagen (8.08) were higher than those of RPR by ADP (2.59), by AA (2.05), by collagen (4.73), or by PFA-100 (2.63). This prospective study documents that the evaluation of platelet reactivity addressed to identify patients at risk of thrombotic events on dual antiplatelet treatment has to be carried out by methods able to explore different pathways.

ADAMTS-13 activity in the presence of elevated von Willebrand factor levels as a novel mechanism of residual platelet reactivity in high risk coronary patients on antiplatelet treatment.

BACKGROUND: The pathophysiologic mechanisms leading to residual platelet reactivity (RPR) on antiplatelet therapy, a condition high prevalent in patients with acute coronary syndrome, are not yet elucidated. In the acute phase of coronary artery disease large amounts of ultra large VWF multimers (ULVWF) are released and cleaved by the activity of ADAMTS-13. OBJECTIVE: Aim of this study was to evaluate the relationships between VWF antigen (VWF:Ag) levels, collagen binding activity of VWF (VWF:CB), ADAMTS-13 and interleukin-6 (IL-6) levels in affecting platelet response to dual antiplatelet treatment. METHODS: In 159 acute coronary syndrome (ACS) patients undergoing percutaneous coronary interventions we measured platelet function by platelet aggregation with two agonists [1 mM arachidonic acid (AA) and 10 microM ADP]. We defined patients with RPR those with platelet aggregation by AA >20% and/or ADP (10 micromol) >70%. RESULTS: We found significantly lower ADAMTS-13 activity, elevated IL-6, VWF:Ag and VWF:CB levels in patients with RPR. A lower ADAMTS-13 activity was present in patients with VWF:Ag and VWF:CB in the upper tertile. At the multivariate analysis ADAMTS-13 activity and IL-6 were independent risk factors for RPR. CONCLUSION: Our results indicate that ADAMTS-13 activity and IL-6 levels independently affect RPR and suggest that, by different pathways, both are involved in the variable response to antiplatelet therapy.

Residual platelet reactivity is an independent predictor of myocardial injury in acute myocardial infarction patients on antiaggregant therapy.

In this study we sought to evaluate if platelet function measured after percutaneous coronary intervention (PCI) affects the severity of myocardial infarction (MI), measured by markers of cardiac necrosis. We measured platelet function by both a point-of-care assay (PFA-100) and platelet-rich plasma aggregation by two agonists (arachidonic acid -AA- and 2 and 10 microM ADP) in 367 patients with MI after PCI (200 patients on dual antiplatelet agents - group A- and 167 on dual antiplatelet agents plus GpIIb/IIIa inhibitors - group B). One hundred twenty-one (32.9%) patients were found to have a residual platelet reactivity (RPR) by PFA (CT/EPI <203 sec): 74/200 (37%) in group A and 47/167 (28.1%) in group B (p = 0.07). In 129 (35.1%) patients we found a RPR by AA-PA: 80/200 (40%) in group A and 49/167 (29.3%) in group B (p < 0.05). Seventeen out of 367 (4.6%) were found to have a RPR by ADP2-PA [15/200 (7.5%) in group A and 2/167 (1.2%) in group B; p < 0.005] and 88/367 (23.9%) by ADP10-PA [64/200 (32%) in group A and 24/167 (14.4%) in group B, p < 0.0001]. CK-MB and cTnI mean peak values were significantly higher in the first tertile of CT/ADP and CT/EPI distribution with respect to the other tertiles and they were significantly higher in patients with RPR by CT/EPI in both group A and group B patients. CK-MB and cTnI peak values were significantly higher in the third tertile of AA-PA, ADP 2 microM-PA and ADP 10 microM-PA distribution with respect to the other tertiles and were significantly higher in patients with RPR by AA-PA and by ADP 10-PA in both group A and group B patients. Multivariate analysis revealed platelet function as an independent predictor of CK-MB and cTnI peak values in both groups of patients independently of clinical, laboratory ad procedural parameters. In conclusion, we found that the severity of MI in patients with MI undergoing primary PCI is influenced by a persistent platelet activation on multiple antiplatelet therapy.

Comparison of different methods to evaluate the effect of aspirin on platelet function in high-risk patients with ischemic heart disease receiving dual antiplatelet treatment.

Patients with coronary artery disease (CAD) receiving aspirin therapy with a residual platelet reactivity (RPR) may be at increased risk of ischemic vascular events. Point-of-care (POC) methods PFA-100 (Dade-Behring, Marburg, Germany) and VerifyNow (Accumetrics, San Diego, CA) assays have been suggested as rapid tools to evaluate RPR. We compared PFA-100 closure times by collagen/epinephrine and VerifyNow Aspirin assays with light transmission aggregation (LTA) induced by 1 mmol/L of arachidonic acid in 484 patients with CAD undergoing percutaneous coronary intervention and receiving dual antiplatelet therapy. RPR was detected in 30.0% of patients by LTA, in 32.4% by PFA-100, and in 14.3% by VerifyNow. Significant correlations were found among 3 methods (all P < .0001). In relation to the presence or absence of RPR by LTA and PFA-100, by LTA and VerifyNow, and by PFA-100 and VerifyNow, samples were significantly concordant (all P < .0001). Assuming LTA as the reference method, PFA-100 and VerifyNow showed sensitivity of 62.1% and 39.3% and specificity of 80.2% and 96.4%, respectively. The cutoff values for POC methods need to be defined for clinical use.

Usefulness of aspirin resistance after percutaneous coronary intervention for acute myocardial infarction in predicting one-year major adverse coronary events.

Recently, great interest has focused on the phenomenon of aspirin resistance, which may be defined as clinical or laboratory resistance. Monitoring the antiplatelet effect appears to be relevant in the presence of clinical implications, but no data are available on the possible clinical implications of the failure of aspirin to inhibit tests of platelet function in the setting of acute coronary syndromes. This study evaluated the role of aspirin resistance in the occurrence of 1-year major adverse coronary events (MACEs) in patients with acute myocardial infarction (AMI) who have undergone percutaneous coronary intervention (PCI). We prospectively evaluated 146 patients (115 men and 31 women; median age 65 years, range 30 to 84) with AMI who underwent primary PCI. Exclusion criteria were the use of glycoprotein IIb/IIIa inhibitors, hematocrit