Platelet function testing after acute myocardial infarction: The correlation among various assays is insufficient

AimHigh on-treatment platelet reactivity (HPR) after Acetylsalicylic acid (ASA) and/or Clopidogrel was identified by four different platelet function assays in high risk acute myocardial infarction patients. Correlation among the methods was examined and variability in the measurement of each platelet function assay was evaluated.MethodsEach of the 53 patients was sampled twice for LTA, PFA-100/200, Multiplate®, and VerifyNow® platelet function assays in the range of 3–5 days after a myocardial infarction. Non-parametric correlation and linear regression were used to assess the variability in the data.ResultsAll HPR platelet function assays for Clopidogrel are significantly correlated, however, the correlation values are only moderate. The correlation among the four assays for ASA is generally low and insignificant. Low reproducibility of HPR measurements and no significant correlation between Troponin I value and HPR were observed, both for ASA and Clopidogrel. No significant correlation between the type of acute coronary syndrome and HPR was observed, both for ASA and Clopidogrel.ConclusionAt least two methods to identify HPR are recommended. The average of at least two measurements is recommended for any assay.