A study on the effects of allele cyp2c19*2, cyp2c19*3 and some factors related to clopidogrel responsiveness in patients with cerebral infarction

and hematologic stages, play an important role in the formation and development of thrombosis-atherosclerosis of brain arteries and increased the activation of platelet after cerebral blood vessel is blocked, platelets are aggregated at the micro vessels in the anemia region, releasing substances acting on blood vessels. Classification of cerebral infarction Classify cerebral infarction according to TOAST. 1.1.4. Epidemiology of cerebral infarction The rate of cerebral infarction accounts for 85% of the total number of strokes, including 17% from infarction caused by heart, 4% from carotid atherosclerosis, 64% from other reasons. Recurrent cerebral strokes account for about 25% of all types of the brain strokes. Using anti-platelet aggregation medication is an important therapy to prevent recurrent cerebral infarction. 1.1.5. Clopidogrel in the treatment and prevention on cerebral infarction Clopidogrel is an anti-platelet aggregation drug, approved by the World Stroke Organization for the use of prophylaxis to prevent relapse of cerebral infarction. Factors affecting clopidogrel responsiveness 1.2.1. Pharmacology of clopidogrel Clopidogrel belongs to the thienopyridine group, as a precursor, after uptake metabolism in the liver it makes up 80-85% of the inactive derivatives and 15% of the active ingredient which has anti-platelet aggregation activity. Clopidogrel is metabolized in the liver by enzymes such as CYP2C19, CYP3A5, CYP2C9, CYP2B6, CYP1A2, in which the enzyme CYP2C19 plays the most important role. 1.2.2. The responsiveness of clopidogrel in the prophylactic treatment of cerebral infarction There have been patients with cerebral infarction who used clopidogrel but still relapse cerebral infarction. Because the responsiveness of clopidogrel is different in individuals. Therefore, the authors proposed the notion of poor responsiveness or clopidogrel resistance. 1.2.3. The concept and method of assessing the responsiveness of clopidogrel - Clopidogrel resistance: a situation in which a metabolite from clopidogrel uncompleted blocks P2Y12 receptors on platelet membranes. The results are measured by platelet aggregation measurement test, based on platelet inhibition mechanism of clopidogrel in patients adhering to clopidogrel. - The concept of anti-clopidogrel is also understood as non-responsiveness, high platelet activation after treatment or residual platelet activation is calculated by the maximum platelet aggregation after treatment. Clopidogrel resistance criteria: platelet aggregation is tested by LTA-ADP method 5 µg/l > 50% after taking clopidogrel enough dose, enough time. 1.2.4. Some non-gene CYP2C19 factors related to clopidogrel responsiveness - Normally, the elderly has a decline in CYP enzyme system activity and a high rate of use of drugs metabolized by CYP, suffering from comorbid diseases which affect clopidogrel metabolism via CYP enzyme system. - In female - to limit bleeding by menstrual by increasing the likelihood of platelet response, which is affected by the female hormone and the alternative therapeutic hormones therefore it relates to clopidogrel response. - Obesity increases leptin, which promotes lipid oxidation, stimulates inflammatory factors that increase platelet activation. - Diabetes reduces clopidogrel response due to (1) increasing clopidogrel hydrolysis into inactive substance, (2) decreasing activity of CYP2C19 enzyme, (3) decreasing absorption of clopidogrel in gastrointestinal tract, (4) increasing hydrolyzate the active products of clopidogrel. - Increased CRP causes platelet adhesion to vascular endothelial cells under normal flow conditions through P-selectin, thereby reducing clopidogrel response. Low plasma albumin decreases clopidogrel response, because low albumin increases the coverage of platelet on surface. 1.2.5. Effect of alleles CYP2C19*2, CYP2C19*3 on clopidogrel responsiveness - Clopidogrel exists in precursors form, to affect on anti-platelet aggregation, they need to be metabolized into active substances, in which the enzyme CYP2C19 plays a major role. CYP2C19 is a polymorphic gene, so the responsiveness of drugs metabolized by the CYP2C19 enzyme is also diverse. The gene CYP2C19 is composed of 2 alleles CYP2C19. The allele CYP2C19 has been identified with more than 35 variants, each denoted by the numbers *1, *2, *3, *4. Allele CYP2C19*1 has phenotypic of enzyme with normal activation. Alleles CYP2C19*2 CYP2C19*3, CYP2C19*4 ... have enzyme phenotype that are lost function and inactivation. Meanwhile, allele CYP2C19*17 gives the enzyme phenotype which increases activation in drug metabolism. Research in several Asian countries found that the rate of people carrying the allele CYP2C19*1 still accounts for the most, followed by the carriers of the allele CYP2C19*2, with a low rate of CYP2C19*3. Allele CYP2C19*17 is uncommon, other alleles are rare in Asians. - There have been many clinical studies proving that the carriers of alleles CYP2C19*2 and CYP2C19*3 show poor response or resistance to clopidogrel. On March 12, 2010 US FDA issued a warning about reducing the effect of clopidogrel due to reduced ability to metabolize drugs into the active form in patients who carry reduced functional alleles CYP2C19. Domestic and foreign research 1.3.1. Research in the world Research of clopidogrel responsiveness have been conducted since 2003, mainly in cardiovascular patients using clopidogrel. Since 2009, there are studies of clopidogrel responsiveness in patients with cerebral infarction such as those by Kim H. et al., Fifi J.T.et al and Yang J. et al. 2013. These studies found that patients carrying reduced function alleles CYP2C19 reduce clopidogrel responsiveness. There are also a number of factors such as high age, female sex, obesity, diabetes, and increased CRP related to clopidogrel responsiveness. 1.3.2. Domestic research In Vietnam, there are studies by Do Quang Huan. et al. in 2013 or Vu Thi Thom et al. 2018 on clopidogrel responsiveness. The studies had small sample, studying objects were patients with coronary artery disease or healthy people, patients were given clopidogrel combined with aspirin. So far, in Vietnam, research on the factors affecting clopidogrel responsiveness in cerebral infarction patients has not been published. CHAPTER 2: OBJECTS AND METHODOLOGY Objects 248 patients with cerebral infarction (genetic testing in 144 first patients) were treated at Stroke Department, 103 Military Hospital from May 2017 to August 2018 Inclusion criteria The patients have enough 4 following criteria: Diagnosed according to the definition of brain stroke by World Health Organization in 1980. (2) There are images of cerebral infarction on computerized tomography. (3) Use clopidogrel 75 mg/day for at least 7 consecutive days. (4) Neuroprotective drugs with a common regimen: Cerebrolysin 20 ml IV, Piracetam 8 g IV, Choline alfoscerate 2 g IM. Exclusion criteria (1) Allergy to clopidogrel, (2) using anticoagulants or other antiplatelet drugs which is different from clopidogrel before the study time within 2 weeks and during the study period, (3) use thrombolytic drugs to treat cerebral infarction in the acute phase, (4) being angioplasty, stenting or endothelial carotid dissection (5) severe water and electrolyte disturbances, (6) consciousness disorders or cerebral infarction area greater than 1/3 of the dominant area of ​​the middle cerebral artery on CT, (7) images of cerebral bleeding on CT, (8) Hemoglobin 160g/l, (9) Platelets 450 G/l, (10) being hemostatic coagulopathy disease, (11) have underlying diseases: Myocardial infarction, atrial fibrillation, heart failure grade 3 and 4 (12) Hepatitis, cirrhosis, liver cancer. (13) have glomerular filtration rate < 30ml/min/1.73m2 skin or are on dialysis cycle (14) have evidence of infection and using antibiotics to treat and do not agree to participate in the study. 2.2. Methodology 2.2.1. Research design The study is designed according to a research method, described cross-sectional, with analysis. 2.2.2. Standards and methods of testing - Cropidogrel resistance standard: Clopidogrel resistance when platelet aggregation discontinuation > 50%, after using clopidogrel 75 mg/day and use ≥ 7 days, testing performed by LTA-ADP method 5µmol/l (measuring platelets aggregation by optical transmission method). LTA is considered the gold standard in platelet aggregation evaluation and is the method to test other methods. The test was performed in 248 patients at the Department of Hematology, Military Hospital 103. - Allele CYP2C19*2, CYP2C19*3 tests in the first 144 patients according to order of 248 patients. Test based on the Sanger principle with a pair of primers set from IDT-USA and conducted at Department of Biological and Medical Genetics - Military Medical Academy. 2.3. Data processing Data processing by using SPSS 20.0 statistical software. CHAPTER 3: RESULTS 3.1. General characteristics of patients Average age 67.21 ± 11.04, male 57.26%, female 42.74%, patients were given clopidogrel for at least 7 days and at most 12 days, an average of 8.34 ± 0.80 days. The average duration of disease was 2.23 ± 1.98 days treated with clopidogrel. 3.2. Some non-gene CYP2C19 factors related to clopidogrel responsiveness. Figure 3.6. The rate of clopidogrel resistance The rate of clopidogrel resistance is 34.68% Table 3.10. Clopidogrel resistance in age groups according to gender. Age (year) n = 248 Resistance n = 86 Non resistance n = 162 p <40 (n=3) Male, n(rate %) 0 (0.0) 3 (100) unidentified Female, n(rate %) 0 (0.0) 0 (0.0) 40- 49 (n=9) Male, n(rate %) 1 (50.0) 1 (50.0) > 0.05 Female, n(rate %) 2 (28.57) 5 (71.43) 50-59 (n=50) Male, n(rate %) 7 (20.59) 27 (79.41) > 0.05 Female, n(rate %) 6 (37.50) 10 (62.50) 60-69 (n=82) Male, n(rate %) 21 (42.0) 29 (58.0) > 0.05 Female, n(rate %) 11 (34.38) 21 (65.62) 70-79 (n=59) Male, n(rate %) 17 (50.0) 17 (50.0) < 0.05 Female, n(rate %) 4 (16.0) 21 (84.0) ≥ 80 (n=45) Male, n(rate %) 7 (36.84) 12 (63.16) > 0.5 Female, n(rate %) 1 10 (38.46) 16 (61.54) In the age group 70-79, the resistance rate in male is higher than female, with p <0.05. Table 3.11. Platelet aggregation at age > 60 and < 60. Age group n (n = 248) PA () p Age < 60 62 36.14 ± 19.47 % < 0.05 Age ≥ 60 186 43.50 ± 19.99 % Platelet aggregation in the age group ≥ 60 years is higher than in the group < 60 years old, with p < 0.05. - Related BMI and clopidogrel responsiveness Table 3.14. Relationship between BMI and clopidogrel resistance BMI (kg/m2) Resistance n = 86 Non resistance n = 162 p n rate % n rate % <18,5 (n = 25) 5 20 10 80 < 0,05 18,5 - 22,9 (n = 137) 36 26.28 101 73.72 23 - 24,9 (n = 46) 20 43.49 26 56.52 25 - 29,9 (n = 38) 23 60.53 15 39.47 ≥ 30 (n = 2) 2 100 0 0.0 The rate of patients with clopidogrel resistance increased with increasing level of BMI, the difference was statistically significant with p < 0.05. Cut-off point Sensitivity Specificity AUC % p 24 kg/m2 45.35 83.95 67.07 < 0.05 Figure 3.10. ROC curves relate to BMI and resistance Table 3.17. The relation between alcoholism, smoking and co-morbidity and clopidogrel resistance Alcoholism, smoking and co-morbidity Resistance n = 86 Non resistance n = 162 p Smoking, n (rate %) 20 (23.26) 35 (21.61) > 0.05 Alcoholism, n (rate %) 10 (11.63) 11 (6.79) > 0.05 Diabetes, n (rate %) 37 (43.02) 44 (27.16) < 0.05 Hypertension, n (rate %) 78 (90.70) 133 (82.10) > 0.05 Gout, n (rate %) 6 (6.98) 7 (4.32) > 0.05 The rate of patients with diabetes in the clopidogrel-resistance group was higher than those in non-resistance group (43.02% compared to 27.16%), which the difference was statistically significant with p < 0.05. Table 3.18. Odds ratio between alcohol and non-alcohol use, smoking and non-smoking, co-morbidity and without co-morbidity with clopidogrel resistance Factors Clopidogrel resistance OR 95%CI p Smoking 1.10 0.59-2.05 > 0.05 Alcoholism 1.81 0.73-4.44 > 0.05 Diabetes 2.03 1.17-3.51 < 0.05 Hypertension 2.13 0.93-4.88 > 0.05 Gout 1.66 0.54-5.11 > 0.05 Diabetes increases the risk of clopidogrel resistance with OR = 2.03 (95% CI: 1.17-3.51, p < 0.05). Table 3.21. The relation between biochemical indices and clopidogrel resistance Biochemical index Resistance n = 86 () Non- resistance n = 162 () p Albumin (g/l) 39.93 ± 3.28 40.81 ± 3.12 < 0.05 Protein (g/l) 73.95 ± 6.56 74.03 ± 5.71 > 0.05 Creatinin (umol/l) 89.07 ± 23.14 83.83 ± 17.05 > 0.05 eGFR (mL/min/1,73m2) 74.96 ± 19.63 77.26± 16.05 > 0.05 Acid uric (mmol/l) 385.65 ± 109.58 357.69 ± 92.17 > 0.05 Homocysteine (umol/l) 11.56 ± 13.27 10.10 ± 4.63 > 0.05 CRP (mg/l) 3.36 (0.21;100) 1.8 (0.17;100) < 0.05 Albumin serum in clopidogrel-resistance group was 39.93 ± 3.28 g/l, lower than in non-clopidogrel group (40.81 ± 3.12 g/l), the difference was statistically significant with p < 0.05. Figure 3.13. ROC curve diagrams related to CRP, albumin and resistance Serum CRP ≥ 4.67 mg/l was at risk of causing clopidogrel resistance with sensitivity 39.54%, specificity 78.39%, p < 0.05. Table 3.26. The relation between intra carotid arterial ultrasound index and clopidogrel resistance Parameter Resistance n = 86 Non resistance n= 162 p IMT () 1.87 ± 0.79 mm 1.71 ± 0.96 mm > 0.05 Narrow () 18.33 ± 16.51% 14.39 ± 16.56% > 0.05 Atheroma Yes (%,n) 60 (24.19) 85 (34.27) < 0.05 No (%,n) 26 (10.48) 77 (31.05) OR 2.042 (95%CI, 1.175-3.551) The rate of patients had clopidogrel resistance in the atherosclerotic group was higher than those in non-atherosclerotic group with p < 0.05. Table 3.28. The relation between treatment drugs and clopidogrel resistance Treatment drugs Resistance n = 86 Non-resistance n = 162 p Statin, n (rate %) 31 (36.05) 77 (47.53) > 0.05 Calcium channel blocker, n (rate %) 58 (67.44) 104 (63.96) > 0.05 ACE inhibitor, n (rate %) 33 (38.37) 63 (38.89) > 0.05 Insulin, n (rate %) 12 (13.95) 7 (4.32) < 0.05 Sulfamide, n (rate %) 5 (5.81) 10 (6.17) > 0.05 Metfomin, n (rate %) 9 (10.46) 17 (10.49) > 0.05 The rate of patients using insulin in resistant group was higher than in non- resistance group with p < 0.05. Table 3.29. Odds ratio between using and not using treatment drugs with clopidogrel resistance Factors Clopidogrel resistance OR 95%CI p Statin 0.62 0.36-1.07 > 0.05 Calcium channel blocker 1.22 0.70-2.12 > 0.05 ACE inhibitor 0.99 0.57-1.67 > 0.05 Insulin 3.59 1.36-9.50 < 0.05 Sulfamide 0.94 0.31-2.84 > 0.05 Metformin 1.00 0.42-2.34 > 0.05 Using insulin increases the risk of clopidogrel resistance to OR = 3.59 (95% CI: 1.36-9.49; p < 0.05) 3.3. The effects of alleles CYP2C19*2, CYP2C19*3 on clopidogrel responsiveness Figure 3.17. Distribution rate of alleles CYP2C19 Table 3.34. The effects of genotype on clopidogrel responsiveness Genotype CYP2C19 (n) PA (%) p *1/*1 (6) 30.00 ± 14.97 < 0.05 *1/*2 (75) 39.20 ± 18.02 *1/*3 (5) 40.60 ± 10.71 *2/*3 (58) 47.02 ± 18.40 Total (144) 42.01 ± 18.29 Platelet aggregation in patients carry 2 reduced functional CYP2C19 alleles (47.02 ± 18.40%) was higher than in patients carry 1 or without reduced functional allele CYP2C19 with p > 0.05. Table 3.35. The effects of genotype on clopidogrel resistance Genotype CYP2C19 Resistance n = 48 Non resistance n = 96 p *1/*1, *1/*2, *1/*3 (n, rate %) 22 (45.83) 64 (66.67) < 0.05 *2/*3 (n, rate %) 26 (54.17) 32 (33.33) Total (n, rate %) 48 (33.10) 96 (66.90) The rate of clopidogrel resistance in patients carried two reduced alleles is higher than in patients without reduced function alleles or carried 1 reduced function allele with p < 0.05. Table 3.36. Multivariate logistic regression analysis of factors affecting clopidogrel resistance Risk factors OR 95%CI p Diabetes 0.55 0.19 -1.57 > 0.05 BMI (kg/m2) 1.28 1.11 – 1.47 < 0.05 Albumin plasma (g/l) 0.86 0.74 – 0.99 < 0.05 CRP plasma (mg/l) 1.04 1.00- 1.08 < 0.05 IMT (mm) 1.20 0.80 - 1.81 > 0.05 Insulin 2.30 0.80 -17.96 > 0.05 Genotype CYP2C19*2/*3 2.48 1.11 – 5.54 < 0.05 Patients carrying two reduced functional CYP2C19 alleles increased the clopidogrel resistance highest with OR = 2.48 (95% CI: 1.11-5.54). Chapter 4: DISCUSSION 4.2. Some non- gene CYP2C19 factors related to clopidogrel responsiveness 4.2.2. The relation between gender and clopidogrel responsiveness In the study, age from 70 to 79, the rate of clopidogrel resistance in male is 50.0%, higher than that in female (16.0%), statistically significant with p < 0.05. Also, males are more likely to use medications to treat comorbid diseases than females. Most of them are drugs metabolized by CYP enzymes. Cabrera M.A.S. et al. found that elderly patients who used multiple drugs metabolized by the CYP enzyme system had a high risk of causing drug interactions thereby reducing the effectiveness of the combined drugs. 4.2.3. The relation between age and clopidogrel responsiveness The age group ≥ 60, platelet aggregation is 43.50 ± 19.99% which is higher than the one in the age group < 60 (36.14 ± 19.47%). The difference is statistically significant with p < 0.05. Thus, age ≥ 60 is associated with decrease of clopidogrel response. Elderly patients are at risk for poor response to clopidogrel due to average volume of platelet is high. In addition, a decrease in the activity of CYP P450 enzymes in the elderly is the cause of poor response to clopidogrel. 4.2.4. The effect of BMI on clopidogrel responsiveness In the study, the rate of clopidogrel resistance increases with BMI. With BMI ≥ 24 kg/m2 it is predicted the risk of causing clopidogrel resistance with sensitivity 45.35%, specificity 83.95%, with p < 0.05. In 2016, in the study by Dogan A. et al, the rate of clopidogrel resistance in patients with BMI < 30 was 28.57%; in patients with BMI ≥ 30 was 56.67%, the difference was statistically significant with p < 0.05. Dogan A. et al. suggested that leptin is an elevated protein in obese people. Platelets have receptors of leptin at the surface, thus increasing leptin in the blood causing increased platelet aggregation through mediators ADP. The author suggested that obese patients with hyperleptinemia may have to consider choosing appropriate clopidogrel dose (according to weight). 4.2.6. The relation between alcoholism, smoking and comorbidities and clopidogrel responsiveness - The relation between diabetes and clopidogrel responsiveness. From the research results, the rate of diabetes in clopidogrel-resistance group is higher than in non- resistance group, statistically significant difference with p < 0.05. In 2015, Su J.F. et al. found diabetes related to clopidogrel resistance in ischemic stroke patients: the rate of diabetes in non-clopidogrel resistance group was 5.95%; in the clopidogrel resistance group was 35.29%, the difference was statistically significant with p < 0.05. Vinik A.I. suggested that platelets of type 2 diabetics increased adhesion to vascular endothelial cells more than normal people. Loss of prostacylin and nitric oxide sensitivity in limiting platelet adhesion to vascular walls is a major deficiency of platelet function in type 2 diabetes. 4.2.7. The relation between blood biochemical indices and clopidogrel responsiveness In the study, the average of serum albumin in the resistant group is lower than in the non-resistant group, the difference is statistically significance with p < 0.05. In the study by Su J. et al. 2014 on patients with coronary artery stent, serum albumin in the clopidogrel-resistant group was 37.73 ± 5.03 g/l, in the non- resistant clopidogrel group was 39.95 ± 5.02 g/l, the difference was statistical significance with p < 0.05. Explaining for the reason of the decrease in clopidogrel response in patients with low albumin, Paar M. and his colleagues found that people with low albumin had increased platelet adhesion, increasing the risk of thrombosis. - The median CRP in the resistant group is higher than in the non- resistant group, the difference is statistically significant with p < 0.05. In the study by Su J.F. et al. 2015, found that serum hs-CRP in clopidogel resistant group had a median of 4.12 (2.12; 11.97) mg/l, higher than in non- resistant groups with serum hs-CRP median 0.95 (0.5; 6.25) mg/l, the difference was statistically significant with p <0.05. CRP is thought to influence platelet effects by increasing platelet adhesion to endothelial cells, inhibiting activation of plasminogen I, and causing instability of atheroma. For patients with ischemic stroke using clopidogrel, when CRP ≥ 4.67 mg / l has diagnostic value of clopidogrel resistance with sensitivity 39.54%, specificity 78.39%, statistically significant with p < 0.05. 4.2.10. The relation between carotid artery ultrasound indicators and clopidogrel responsiveness The clopidogrel resistance rate in the group with carotid atherosclerosis is higher in the group without carotid atherosclerosis, the difference is statistically significant with p < 0.05. Koyama H. ​​et al. 2003 found that P-selectin was an independent factor related to the thickness of carotid artery endothelial, increasing P-selectin causing increased activation of platelet. 4.2.11. The relation between treatment drugs and clopidogrel responsiveness - Diabetes treatment drugs: + Insulin: The rate of patients using insulin in the clopidogrel-resistant group is 13.95%, in the non- resistant group is 4.32%, the difference is statistically significant with p < 0.05. In our study, taking insulin increased the risk of clopidogrel resistance with OR = 3.59 (95% CI: 1.36-9.50, p < 0.05). Anfossi G. et al. found that with physiological or slightly elevated insulin levels increases cGMP synthesis through activation of guanylate cyclase. cGMP inhibits the activities of platelet that reduces adhesion and platelet aggregation. If insulin is higher than the physiological level, it increases cGMP catabolism through activation of phosphodiesterase, thereby increasing the ability of adhesion and platelet aggregation. 4.3. The effects of CYP2C19*2, CYP2C19*3 alleles on clopidogrel responsiveness From the research results on 144 cerebral infarction patients who are genetically tested, we found: The rate of patients carrying at least one allele CYP2C19*1 (allele having function of clopidogrel normal metabolism) in our study is 59.72%, which is equivalent to the research result of the CYP2C19*1 ratio in Asian by Hiroshi Y.'s Asia (2014) was 61.5%. The rate of patients carrying at least one clopidogrel-reducing metabolic allele (CYP2C19*2, *3) in our study is higher than that of other international and domestic studies. We think that it is necessary to investigate the polymorphism of CYP2C19 in ischemic stroke patients in Vietnam on a large scale. In the study, the phenotype with an extensive metabolic function (EM is 4.17%, metabolism level (IM) is 55.56%, poor clopidogrel metabolism (carrying 2 reduced alleles) is 40.29%. In 2012, Yang J. et al. studied in Chinese patients with cerebral infarction: the phenotype had an extensive metabolism function 47.54%, intermediate metabolism 45.36%, poor metabolism 7.1%. Thus, stroke patients with cerebral infarction in our study who have the phenotype with an extensive clopidogrel metabolism function take a small rate, poor metabolism is high rate. This is a warning for stroke patients who are taking clopidogrel. - The effects of allele CYP2C19*2, *3 on the responsiveness of clopidogrel: Platelet aggregation increased with patients who do not carry or carry 1 or 2 non-function alleles (CYP2C19*2, *3), the difference is statistically significant with p < 0.05. Research by Yang J.C. et al. (2013), found in patients with cerebral who had platelet aggregation (tested by LTA-ADP 5 µg/l) after 7 days of using clopidogrel with 75 mg/day, corresponding with 3 gene groups: CYP2C19*1/*1; CYP2C19*1/*2 + *1/*3; CYP2C19*2/*3 is 26.9 ± 17.5%; 38.9 ± 24.3%; 47.6 ± 32.0%, the differences in platelet aggregation among gene groups was statistically significant with p < 0.05. Our research, by Yang J.C. et al, and Jeong Y.H. et al. showed that patients with reduced functionl alleles (CYP2C19*2, CYP2C19*3) reduced clopidogrel responsiveness. The results show that the group of patients with genotypes CYP2C19*1/*1, CYP2C19*1/*2, CYP2C19*1/*3 have low rate of clopidogrel resistance, accounting for 45.83%, patients with