Multiple Electrodes Aggregometry - a New Method of Assessment of Aspirin Low Responder Status in Patients Undergoing Percutaneous Coronary Intervention (original) (raw)
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Thrombosis Research, 2008
Unresponsiveness to clopidogrel or aspirin has been reported in patients with acute coronary syndrome (ACS). Platelet aggregometry (PA) and the Impact-R [Cone and Plate(let) Analyzer (CPA) technology, measuring whole blood platelet adhesion under flow conditions] were compared in detecting laboratory unresponsiveness to clopidogrel and aspirin among ACS patients. Platelet-rich plasma (PRP) samples were evaluated in 404 patients by PA using adenosine diphosphate (ADP) and arachidonic acid (AA) and whole blood samples by the Impact-R ADP-and AA-response tests. The first cohort (n = 114) was assayed by PA on days 1 and 4 of the onset of ACS. A patient with relative decrease of ≤10% in ADPinduced maximal platelet aggregation after clopidogrel treatment was defined as laboratory non-responding (NR) patient to clopidogrel. This relative value correlated well with an absolute value of ADP-induced aggregation ≥70%. A patient with an absolute value of AA-induced maximal aggregation ≥ 60% was defined as laboratory Thrombosis Research (2008) 122, 336-345 NR patient to aspirin. The second cohort (n = 290) was tested on day 4 by both systems and results analyzed by receiver operating characteristic curve. The following cut-off values of the Impact-R surface coverage were obtained: ≤ 2.8% and ≤3.4% for clopidogrel and aspirin NR patients, respectively. The incidence of NR patients to clopidogrel and aspirin, according to the two methods was 27% and 22%, respectively. Impact-R compared to PA in detecting clopidogrel and aspirin NR patients revealed: 79% and 82% agreement, 71% and 73% sensitivity, 83% and 86% specificity, respectively. In conclusion, the Impact-R and PA results demonstrated high degree of similarity.
European Journal of Internal Medicine, 2011
Background: Studies on the prognostic significance of residual platelet reactivity despite the use of dual antiplatelet agents are limited and seldom extend beyond 1 year. Methods: This study enrolled 144 patients treated with standard-dose aspirin and clopidogrel and undergoing percutaneous coronary intervention (PCI). Platelet reactivity was measured by the Platelet Function Analyzer-100 (PFA-100) just before PCI and presented as collagen/epinephrine closure time (CEPI-CT) and collagen/ adenosine diphosphate closure time (CADP-CT). Primary endpoint included cardiovascular death, myocardial infarction, and stroke. Secondary endpoint was the primary endpoint plus hospitalization due to unstable angina or urgent target vessel revascularization. Results: During the 24-month follow-up, 14 patients (9.7%) developed the primary endpoint events and 33 had the secondary endpoints. After controlling possible confounding factors, both CEPI-CT b 193 s and CADP-CT b 95 s were independently predictive of the primary endpoint (hazard ratio = 3.5; 95% confidence interval: 1.04-11.7; p = 0.044 and 5.3; 1.4-20.1; p = 0.015, respectively). Only CADP-CT b 95 s remained significantly predictive of secondary endpoints in the follow-up periods of 0-9 and 9-24 months, during which clopidogrel was mostly discontinued. Conclusion: This study demonstrates that increased residual platelet reactivity measured by PFA-100 CADP-CT consistently predicts the occurrence of cardiovascular events following PCI throughout the 24-month followup period, irrespective of the changes in anti-platelet use.
The American Journal of Cardiology, 2009
Antiplatelet therapy is the mainstay of treatment for patients with cardiovascular disease. However, some patients experience adverse cardiac events despite treatment with single-or dual-antiplatelet (aspirin and clopidogrel) therapy. Some of those events could be caused by low responsiveness to aspirin or clopidogrel. The frequency of this phenomenon has been reported to range from 1% to 45% for the 2 drugs. This wide range arises from the lack of a "gold-standard" definition to assess antiplatelet drug response and differences in assays, agonist concentrations, and cut-off points. Regardless of the variability in the incidence of aspirin or clopidogrel low responsiveness, several studies have indicated a clear relation between clopidogrel or aspirin low responsiveness and cardiovascular events. The evidence for an association between adverse clinical events and the results of ex vivo platelet function tests is stronger for clopidogrel than for aspirin. Currently, there is no established therapeutic approach for managing low response to aspirin or clopidogrel that has been shown in large trials to have clinical benefit. This review focuses on laboratory testing of antiplatelet response to aspirin and clopidogrel, the prevalence of low response, potential mechanisms, clinical significance, and prognostic value of this phenomenon and alternative approaches to optimize treatment in patients with low response to the drugs.
2007
Background: Two point-of-care (POC) systems have been recently proposed as rapid tools with which to evaluate residual platelet reactivity (RPR) in coronary artery disease (CAD) patients. Objectives and Methods: We compared Platelet Function Analyzer-100 (PFA-100) closure times (CTs) by collagen/adenosine 5´-diphosphate (ADP) (C/ADP CT) cartridge and the VerifyNow P2Y12 Assay (VerifyNow) with light transmission aggregation (LTA) induced by 2 and 10 lmol L-1 ADP in 1267 CAD patients on dual antiplatelet therapy who underwent percutaneous coronary intervention. We also performed the vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay by cytofluorimetric analysis in a subgroup of 115 patients. Results: Cutoff values for identifying RPR were: ‡ 54% and ‡ 66% for LTA induced by 2 and 10 lmol L-1 ADP respectively, and ‡ 264 P2Y12 Reaction Units (PRU) for VerifyNow. The cutoff for PFA-100 C/ADP CT was ‡ 68 s. RPR was detected in 25.1% of patients by 2 lmol L-1 ADP-induced LTA (ADP-LTA), in 23.2% by 10 lmol L-1 ADP-LTA, in 24.4% by PFA-100, and in 24.7% by VerifyNow. PFA-100 results did not parallel those obtained with LTA. VerifyNow showed a significant correlation (q = 0.62, P < 0.001) and significant agreement (k = 0.34, P < 0.001) with LTA induced by 2 lmol L-1 ADP. The correlation was similar but the agreement was better between VerifyNow and 10 lmol L-1 ADP-LTA (q = 0.64, P < 0.0001; k = 0.43, P < 0.001). Significant relationships were found between VASP platelet reactivity index and both ADP-LTA and VerifyNow. PFA-100 C/ADP CT did not significantly correlate with any of the other assays. Conclusions: Our results show a significant correlation between LTA and VerifyNow but not the PFA-100 C/ADP assay. Clinical validation studies for POC systems are necessary.
International Journal of Cardiology, 2017
; this author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation; b Centro Diagnostico Italiano, Milano; this author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation; C Dipartimento Cardiovascolare, Policlinico S. Orsola, Bologna; this author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation; d Semeion Research Centre, Roma; this author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation; e Unità Coronarica IRCCS Policlinico San Matteo, Pavia; this author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation, f