Clopidogrel, a commonly used antiplatelet agent for stroke prevention, requires CYP2C19-mediated metabolism for efficacy. Presence of loss-of-function alleles reduce clopidogrel effect, potentially leading to treatment failure. This study aimed to look for association of CYP2C19 polymorphisms with recurrent cardiovascular events. We retrospective chart review of patients who presented to Bangkok International Hospital from Jan 2014 to Dec 2023, for whom CYP2C19 genetic testing was done. Patient were categorized as carriers or noncarriers of loss-of-function alleles. The Essen Stroke Risk Score (ESRS) was used to stratify patients as high risk (≥ 3) or low risk (< 3) for recurrent stroke. Among 126 patients (mean age 70.45 ± 12.48 years, 74.6% male), CYP2C19 phenotypes were distributed as: normal (31%), intermediate (48.4%), poor (12.7%), and ultrarapid metabolizers (7.9%). Compared to noncarriers, carriers exhibited significantly greater rates of recurrent stroke (p=0.028) and recurrent myocardial infarction (p=0.04). Both events were significantly more frequent in carriers who had high ESRS. Pretreatment CYP2C19 genotyping should be considered to prevent adverse outcomes in clopidogrel-treated patients, particularly those with high ESRS. 

Chaisak Dumrikarnlert had completed medical degree at the age of 24 years from Siriraj Hospital, Mahidol University, Thailand. Then he had been training in Thai Board of Internal Medicine, Thai Board of Neurology, and got certificated in Behavioral Neurology subspecialty. He is working at Neuroscience Center, Bangkok International Hospital, took care Neurological patient, especially dementia patient as his field of expertise. He also working as consultant at Memory Clinic of Siriraj Hospital, where he taught resident and fellow of Neurology and Behavioral Neurology. He has been serving as reviewer of Neurology Asia journal and also committee of Bangkok Dusit Medical Service – Institutional Review Board (BDMS-IRB).