title: Different influences of hematocrit on the results of two Point-Of-Care platelet function tests, the VerifyNow assay and multiple electrode platelet aggregometry.
abstract: OBJECTIVE
  Previous studies have reported a considerable association between the VerifyNow (Accumetrics, San Diego, CA, USA) P2Y12 assay results and hematocrit. No reports, however, have described an association between the multiple electrode platelet aggregometry (MEA; Dynabyte, Munich, Germany) adenosine diphosphate (ADP) assay results and hematocrit. This study was conducted to evaluate the influence of hematocrit on the results of 2 different point-of-care platelet function tests.
  
  
  METHODS
  A total of 462 consecutive patients who were undergoing percutaneous coronary intervention were enrolled. Platelet function was evaluated with both the VerifyNow P2Y12 and MEA ADP assays.
  
  
  RESULTS
  Anemic patients (n = 152, 32.9%) demonstrated a significantly higher rate of cardiac death, myocardial infarction, and stroke (5.3% vs. 2.3%, p = 0.046) during the follow-up (median: 18.8 months). Although the VerifyNow P2Y12 assay results demonstrated a significant inverse correlation with hematocrit (r = -0.409, p<0.001), there was no such correlation between the MEA ADP assay results and hematocrit (r = 0.039, p = 0.401). In the multivariate analysis, anemia was an independent predictor of high on-treatment platelet reactivity, defined as a VerifyNow P2Y12 reaction unit level of ≥252.5 (odds ratio = 2.21, 95% confidence interval = 1.39-3.52; p = 0.001). Importantly, this association was independent of an intrinsic change in platelet reactivity as measured by the MEA ADP assay. Adjusting for the influence of hematocrit improved the strength of the correlation between the VerifyNow P2Y12 and MEA ADP assay results.
  
  
  CONCLUSIONS
  Hematocrit significantly influenced the VerifyNow P2Y12 assay results, a phenomenon that was presumably in-vitro. Hematocrit level should therefore be considered when interpreting results of the VerifyNow P2Y12 assay.
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Yun Gi
authors.initials: YG
authors.lastname: Kim
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Jung-Won
authors.initials: JW
authors.lastname: Suh
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Jin Joo
authors.initials: JJ
authors.lastname: Park
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Il-Young
authors.initials: IY
authors.lastname: Oh
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Yoon
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Young-Seok
authors.initials: YS
authors.lastname: Cho
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Youn
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Chae
authors.affiliation: Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Gyeonggi-do, Korea.
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Choi
mesh_terms: D000368:Aged; D000740:Anemia / Q000097:blood / Q000150:complications; D004566:Electrodes; D005260:Female; D006400:Hematocrit; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000097:blood / Q000150:complications; D062645:Percutaneous Coronary Intervention; D010974:Platelet Aggregation; D010979:Platelet Function Tests / Q000295:instrumentation / Q000379:methods*; D019095:Point-of-Care Systems; D012189:Retrospective Studies; D020521:Stroke / Q000097:blood / Q000150:complications