Effect of preanalytical time-delay on platelet function as measured by multiplate, PFA-100 and VerifyNow

BACKGROUND AND AIMS: Platelet function testing may help to identify poor responders to antiplatelet drugs. The aim of this study was to compare three commonly used platelet function tests with special focus on the pre-analytical influence of time-delay on the tested parameters. METHODS: We assessed ADP-induced platelet function by the Multiplate, Platelet Function Analyzer-100 (PFA-100) and VerifyNow in nine healthy volunteers and 36 patients receiving clopidogrel or prasugrel 1 and 3 hours after sampling. RESULTS: The PFA-100 demonstrated non-closure time in 23 patients. A more graded response could be detected with the two other devices. Aggregation in whole blood (Multiplate) decreased after 3 hours compared to 1 hour in all subjects (p < 0.05). Furthermore, aggregation levels obtained by the VerifyNow showed a decrease in patients taking P2Y12 inhibitors after 3 hours (p < 0.05), except in three patients, in whom an increase was observed. CONCLUSION: Responses to ADP are time-dependent after blood sampling for the Multiplate in all subjects and for the VerifyNow in patients on antiplatelet drugs. For both devices, platelet aggregation was reduced 3 hours after sampling which may affect data interpretation and clinical consequences.