Impact of a High-Fat Meal on Assessment of Clopidogrel-Induced Platelet Inhibition in Healthy Subjects

Purpose: We conducted this study to evaluate whether a high-fat meal impacts the ability of various platelet function tests to assess platelet reactivity for patients on clopidogrel.

Methods: Healthy subjects not taking antiplatelet drugs presented after a 12 hour fast. After baseline platelet function assessment, subjects were given a 600 mg dose of clopidogrel. Four hours after the dose, maximum platelet inhibition was tested in the fasting state. Subjects were then provided a standardized high-fat meal, and platelet function was evaluated 2 hours later. Platelet function was assessed by 2 optically dependent assays (LTA and VerifyNow P2Y₁₂) and 2 non-optically dependent assays [vasodilator-stimulated phosphoprotein (VASP) and whole blood aggregometry (WBA)]. Platelet function was compared before and after the high-fat meal with the Wilcoxon matched-pair signed-rank test.

Results: Twelve healthy adults were recruited.  The mean triglyceride level increased following the high-fat meal (79 mg/dL vs. 132 mg/dL; p=0.002). There was no significant change in maximal light transmission as assessed by LTA (range -9% to 11% with 5µM ADP; p=0.15 and -9% to 10% with 20µM ADP; p=0.07). There was a significant change in the area under the curve with 5µM ADP (range -9 to 65; p=0.03) but not with 20µM ADP (range -41 to 63; p=0.18). Although there was no significant change in P2Y12 Reaction Units with the VerifyNow P2Y12 assay (range -28 to 47; p=0.16), the change was correlated with the initial fasting value (Spearman’s rho p=0.01). There was minimal variability with the VASP assay (range -4.4 to 5.4; p=0.35), and no changes were evident with WBA.

Conclusion: The intake of a high-fat meal did not significantly alter platelet function assessment of commonly used platelet function tests. There was more intra-subject variability with the optically dependent compared with non-optically dependent platelet function tests.