Platelet Inhibition

Etiology of Plavix Resistance

  • There is a recognized incidence of clopidogrel resistance in patients with a genetic predisposition: CYP2C19 “nonfunctioning alleles.”
  • In these patients, coronary events may continue despite adequate dosing with clopidogrel, at times with disastrous consequences, necessitating a means for monitoring antiplatelet therapy.

Diagnosis

  • P2Y12 Assay
    • Assay measures plt inhibition by plavix
    • Safe for Procedures+Surgery: <20%
  • P100 Assay
    • Measures plt inhibition due to ASA and plavix

References

  • Simon T, Verstuyft C, Mary-Krause M, et al. Genetic determinants of response to clopidogrel and cardiovascular events (French registry study). N Engl J Med 2009; 360:363-375
  • Collet J-P, Hulot JS, Pena A, et al. Cytochrome P-450 2C19 polymorphism in young patients treated with clopidogrel after myocardial infarction: a cohort study. Lancet 2009; 373:309-317
  • Mega JL, Close SL, Wiviott SD, et al. Cytochrome P-450 polymorphisms and response to clopidogrel. N Engl J Med 2009; 360:354-362
  • Simon T, Verstuyft C, Mary-Krause M, et al. Genetic determinants of response to clopidogrel and cardiovascular events (French registry study). N Engl J Med 2009; 360:363-375
  • Collet J-P, Hulot JS, Pena A, et al. Cytochrome P-450 2C19 polymorphism in young patients treated with clopidogrel after myocardial infarction: a cohort study. Lancet 2009; 373:309-317