Point-of-Care Whole Blood Impedance Aggregometry Versus Classical Light Transmission Aggregometry for Detecting Aspirin and Clopidogrel: The Results of a Pilot Study

Department of Anesthesiology and Intensive Care Medicine, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.
Anesthesia and analgesia (Impact Factor: 3.47). 12/2008; 107(6):1798-806. DOI: 10.1213/ane.0b013e31818524c1
Source: PubMed


We determined whether whole blood impedance aggregometry using the Multiplate detects the effects of antiplatelet drugs as reliably as does classical light transmission aggregometry (LTA) or the platelet function analyzer PFA-100(R).
Multiplate (M) assays, measuring changes in electrical resistance as aggregation units over time (AU*min), and LTA assays induced by collagen (COL), adenosine diphosphate (ADP) or arachidonic acid (AA) and PFA-100 testing, using epinephrine (PFA100-EPI) or ADP (PFA100-ADP) cartridges, were performed simultaneously using arterial blood samples obtained before induction of anesthesia in 70 consecutive patients scheduled for elective coronary artery bypass grafting. Patients in group A (n = 48) served as controls, patients in group B (n = 11) received aspirin 100 mg/d and those in group C (n = 11) aspirin 100 mg/d and clopidogrel 75 mg/d until the day before surgery.
In controls the median (1st, 3rd quartiles) change in impedance AU*min for M-COL (374 [231-469]) was significantly greater than in patients receiving aspirin (164 [86-211], P = 0.0009) or receiving aspirin and clopidogrel (118 [101-244], P = 0.004). M-ADP values in controls were 258 (158-389), in patients receiving aspirin 261 (159-393), and in patients receiving aspirin and clopidogrel 88 (48-231, P = 0.054). M-AA values were significantly lower in patients receiving aspirin alone (45 [28-60], P = 0.0004) or aspirin and clopidogrel (44 [26-221], P = 0.008) than in controls (200 [86-345]). The areas under the receiver operating characteristic curves indicating the ability to discriminate patients taking aspirin from those not taking aspirin were comparable for COL and AA assays using whole blood impedance aggregometry or classical LTA (M-COL 0.84 [P = 0.001], LTA-COL 0.85 [P = < .001], M-AA 0.84 [P = < .001] and LTA-AA 0.87 [P = < .001]), but only 0.74 for PFA-100-EPI (P = 0.03). Similarly, for discrimination of patients not taking antiplatelet drugs from patients taking clopidogrel and aspirin the areas under the receiver operating characteristic curve were also comparable for both aggregometry methods M-COL 0.77 (P = 0.006), LTA-COL 0.78 (P = 0.004), M-ADP 0.74 (P = 0.015), LTA-ADP 0.73 (P = 0.018).
Results achieved with the bedside Multiplate assays were not different than those obtained with classical aggregometry for detecting the effects of aspirin and clopidogrel in preoperative patients scheduled for elective cardiac surgery.

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    • "It is one of the most widely applied platelet aggregometers in Europe. It has been used to study the effects of aspirin,5,6 non-opioid analgesics,7 clopidogrel,8,9 andanticoagulants10 on platelet aggregation. We have previously evaluated clopidogrel and aspirin resistance in different groups of patients with coronary events.11 "
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    ABSTRACT: Objectives: To determine the prevalence of aspirin resistance and associated risk factors based on biochemical parameters using whole blood multiple electrode aggregometry. Methods:The study was conducted at the outpatients cardiology clinic of the Universiti Kebangsaan Malaysia Medical Centre (UKMMC) from August 2011 to February 2012. Subjects on aspirin therapy were divided into two groups; first-ever coronary event and recurrent coronary event. Aspirin resistance was measured by a Multiplate® platelet analyser. Results: A total of 74 patients (63 male, 11 female), with a mean age of 57.93 ± 74.1years were enrolled in the study. The patients were divided into two groups –first-ever coronary event group (n=52) and recurrent coronary event group (n=22). Aspirin resistance was observed in 12 out of 74 (16%) of the study patients, which consisted of 11 patients from the first-ever coronary event group and one patient from the recurrent coronary event group. There were significant correlations between aspirin resistance and age (r = -0.627; p = 0.029), total cholesterol (r = 0.608; p = 0.036) and LDL (r = 0.694; p = 0.012). LDL was the main predictor for area under the curve (AUC) for aspirin resistance. However, there was no association between aspirin resistance and cardiovascular events in both groups in this study. Conclusions: Aspirin resistance was observed in 16% of the study population. LDL was the major predictor of aspirin resistance. No association was found in the study between aspirin resistance with recurrent coronary events.
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    • "MEA (Multiplate, Dynabyte, Munich, Germany) technique evaluates platelet function in whole blood, based on classical whole blood impedance aggregometry [2]. MEA has recently been used to study the effects of aspirin [12,13], nonopioid analgesics [14], clopidogrel [15,16], anticoagulants [17], antifibrinolytics [18], colloids [19], on platelet aggregation. Platelet aggregation as determined by MEA is calculated from the AUC and quantified by arbitrary aggregation units over time (AU*min). "
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    ABSTRACT: To evaluate the optimum timing of aspirin cessation before noncardiac surgeries. We have conducted a pilot study to minimize the aspirin cessation time before various surgeries. Eighty patients who were taking regular aspirin for secondary prevention undergoing elective surgical operations were enrolled in the study. We separated the patients into two groups. The control group had 35 patients who stopped aspirin intake 10 days before surgery. The study group had 45 patients who stopped their aspirin intake and underwent surgery one day after arachidonic acid aggregation tests were within normal limits. Bleeding, blood loss, and transfusion requirements were assessed perioperatively. The mean time between aspirin cessation and aspirin nonresponsiveness were found to be 4.2 days with a median value of 4 days. In addition, the mean time between aspirin cessation and operation day were found to be 5.5 days with a median value of 5 days. No perioperative bleeding, thromboembolic or cardiovascular complications were encountered. Reducing time of aspirin cessation from 7-10 days to 4-5 days is a possibility for patients using aspirin for secondary prevention without increased perioperative complications.
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    • "In this study, platelet function analysis was performed using the Multiplate® platelet analyser (Dynabyte, Munich, Germany. It has been used to study the effects of aspirin7,8, non opiod analgesics9, clopidogrel10,11, anticoagulants12, antifibrinolytics13, colloids14 and temperature15, on platelet aggregation. Multiplate® platelet analyser analyzes whole blood impedance aggregometer. "
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    ABSTRACT: Objectives: To evaluate Aspirin and Clopidogrel resistance/non-responders in patients with acute coronary syndrome (ACS) by using adenosine diposphate and aspirin tests. Methodology: In the study patients with ACS loaded with 300 mg of clopidogrel and 300 mg aspirin and patients on stable daily dose of 75 mg of clopidogrel (more than 3 days) underwent PCI. Response to clopidogrel and Aspirin was assessed by Adenosine Diphosphate (ADP) Test (20 µmol/L) and Aspirin Test (Acetyl Acid) (ASP) 20 µmol/L, respectively, using the Multiplate Platelet Function Analyzer (Dynabyte Medical, Munich, Germany). Results: Sixty four patients were included in this study out of which 57 were with ACS and 7 scheduled for percutaneous coronary intervention (PCI) electively. The proportion of Aspirin good responders and adequate responders were 76.56% and 18.75%, respectively while adequate response and good response to Clopidogrel accounted for 29.7 and 48.4%, respectively Hyperlipidaemia was only co-morbidity associated with higher AUC ADP value (p: 0.046). Hypertriglyceridaemia and serum calcium were weakly correlated with higher AUC ADP serum calcium r=0.08, triglyceride r=0.12. Patients admitted for scheduled PCI and on stable dose of 75mg clopidogrel exhibited lower AUC ADP value as compared to those admitted with acute coronary syndrome given loading dose of 300mg of Clopidogrel. Post loading dose measurement of anti-platelet therapy among ACS patients using the Multiplate Platelet Function Analyzer showed comparable results with other methods. Conclusions : As determined by Multiplate Platelet Function Analyzer, Aspirin resistance/non-responders in this study in acute coronary syndrome patients accounted for 4.69% while Non-responders in Clopidogrel was 21.9%.
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