Pre-procedural platelet reactivity after clopidogrel loading in korean patients undergoing scheduled percutaneous coronary intervention

Aim: pre-procedural platelet reactivity (pr) in korean patients may be greater because the cyp2c19 *2 and *3 variant alleles are more common in korean patients than in caucasians. we investigated the level of pr and the prevalence of high post-clopidogrel platelet reactivity (hppr) after a routine loading dose (ld) of clopidogrel in korean patients. methods: we assessed the pr level at 12 to 24 hours after a 300-mg ld of clopidogrel in 215 patients undergoing scheduled percutaneous coronary intervention (pci) (available cyp2c19 geno-typing: n = 176). pr was measured by conventional aggregometry and verifynow. based on a previous study,hppr was defined as a 5 jltmol/l adp-induced maximal pr > 50%. results: with 5 and 20 jitmol/l adp stimuli,maximal pr were 48.7± 17.1% and 62.1 ± 15.7%,respectively,and the prevalence of hppr reached 52.1%. the highest quartile cut-offs of 5 and 20 μmol/l adp-induced prmax were 64% and 75%,respectively. p2yu reaction unit (pru) was 274 ± 76,and 69.8% [n = 150) showed pru ≥ 240. a carrier of at least one cyp2c19 variant allele showed higher prs than non-carriers. in multivariate regression analysis,carriage of the cyp2c19 variant allele (*2 or *3) was determined to be a significant predictor of hppr (odds ratio 4.202,95% confidence interval 1.996 to 8.850,p<0.001). conclusions: korean patients undergoing scheduled pci cannot achieve adequate pre-procedural platelet inhibition from a 300-mg ld of clopidogrel,which is related with a higher prevalence of the cyp2c19 mutant allele.