Variables influencing Multiplate™ whole blood impedance platelet aggregometry and turbidimetric platelet aggregation in healthy individuals

Abstract

We investigated the relationship between impedance platelet aggregometry (IPA) as measured by the Multiplate system and turbidimetric platelet aggregation (TPA) induced by ADP, arachidonic acid (AA), and collagen; blood cell counts; platelet function analyzer (PFA-100) closure times (CT), and von Willebrand factor (VWF) in 120 well-characterized healthy individuals. Pre-analytical and analytical conditions were standardized comprehensively. Analytical reliability of IPA and TPA and the influence of pre-analytical variables on assay results were also examined. IPA and TPA did not change significantly between 0.5 and 5 hours after blood collection when samples were stored at room temperature. TPA and IPA showed significantly greater intra-assay imprecision than respective TPA induced by the same agonists. Intra-individual variation did not differ significantly between IPA and TPA. The lower limits of reference range (2.5th percentiles) of AAIPA, ADPIPA and collagen IPA determined AM were 37, 20 and 40 AU, respectively. ADPIPA showed significantly lower maximum aggregation values than AAIPA and collagen IPA (P < 0.0001). There were no significant differences in any parameter between males and females. No significant differences between blood group 0 and non-0 individuals were noted with respect to IPA and TPA. IPA did not change significantly during the day. In contrast, TPA measured PM was significantly lower than corresponding values determined a.m. (p < 0.0001). CEPI-CT, CADP-CT and leukocyte counts increased significantly from a.m. to p.m. (P = 0.008 and P > 0.0001, respectively). Donors had significantly greater IPA induced by any agonist than non-donors (P-values < 0.0001, 0.0001 and 0.001, respectively), whereas TPA was not significantly different between donors and non-donors. IPA did not correlate significantly with TPA nor with PFA-100 CT. ADPIPA and collagen IPA correlated significantly with platelet count. TPA was not associated with platelet count. An inverse significant correlation was observed between TPA induced by any agonist and leukocyte count, whereas leukocyte count did not influence IPA. CEPI-CT and CADP-CT correlated significantly with VWF:CBA and with each other but not with TPA. We concluded that IPA and TPA measure different aspects of platelet function. IPA results reflect interactions between platelets, red and white cells, while TPA does not. This explains discrepancies in associations of IPA and TPA with cell counts, time of day and blood donation. The clinical significance of IPA determined using the Multiplate device remains to be determined in studies on patients with platelet dysfunction and under treatment with antiplatelet agents.

Multiple electrode aggregometry in thrombocytopenic haemato-oncologic patients – Influence of haematologic variables

“…Previous studies of healthy volunteers and patients with stable CAD have found that TPC affects Multiplate results, especially when platelet counts are low, but no studies have been identified that tested the blood of patients with actual thrombocytopenia [1][2][3][4][15][16][17]. We found a significant association between TPC and AUC for all four agonists in patients with severe thrombocytopenia, which is in concordance with previous studies in healthy volunteers and CAD patients.…”

“…Würtz, et al [2] and Rubak, et al [4] also found a significant effect of WBC on AUC. Seyfert, et al [15] did not find a significant effect of WBC on AUC in a study on healthy volunteers.…”

Genetic Polymorphisms of Platelet Receptors in Patients with Acute Myocardial Infarction and Resistance to Antiplatelet Therapy

“…The fluids were mixed in a measuring cuvette for 3 min at a constant temperature of 37°C (Mueller et al, 2007;Seyfert et al, 2007). To determine aspirin resistance, arachidonic acid as an inducer was added at a final concentration of 15 mM.…”

“…Nowadays, the so-called golden standard is platelet aggregation testing in platelet-rich plasma (PRP) using light transmission aggregometry (Cattaneo, 2007;Cattaneo et al, 2007). A novel option for determining residual platelet aggregation is the use of multiple electrode aggregometry (MEA) in whole blood (Mueller et al, 2007;Seyfert et al, 2007). It measures electrical impedance between two electrodes in hirudin-treated whole blood.…”

Assessment of platelets and the endothelium in patients presenting with acute coronary syndromes – is there a future?

“…Moreover, lack of standardised cut-offs makes interpretation of different studies difficult, although a good correlation between several methods and the LTA was shown (60,67). Two potential candidates to fulfil clinical needs are the Accumetrics VerifyNow Clopidogrel (P2Y 12 ) assay (68) and the multiple electrode platelet aggregometry (MEA) (69) , which are easy to use and rapid tests appropriate for the acute setting. The MEA implements the principle of impedance aggregometry with no need for blood centrifugation and the ability to assess platelet function in ~ 10 minutes (64).…”