Association of CYP2C19*2 polymorphism with clopidogrel resistance among patients with high cardiovascular risk in Northeastern Mexico / Asociación del polimorfismo CYP2C19*2 con resistencia a clopidogrel en pacientes con alto riesgo cardiovascular en el noreste de México

abstract Objective: Oral antiplatelet drugs are a key to modern pharmacotherapy in cardiovascular atherothrombotic diseases. Clopidogrel (CLO) constitutes the main preventive treatment of atherothrombosis. However, a considerable inter-individual variation in CLO response has been documented, resulting in suboptimal therapy and an increased risk of recurrent adverse effects in some patients. The enzyme CYP2C19 has been reported to be the CYP isoform that activates CLO to its active metabolite. Several single nucleotide polymorphisms in the CYP2C19 gene have been identified as strong predictors of CLO-impaired pharmacological response. At least 16 variants have been associated with changes in CYP2C19 activity. Materials and Methods: The following research was composed of a total of 102 subjects with high cardiovascular risk in the northeast of Mexico, with a maintenance dose of 75 mg of CLO per day. The platelet reactivity was measured with VerifyNow P2Y12 assay, while the presence of CYP2C19*2 was identified by real-time polymerase chain reaction. Results: Patients were categorized by CYP2C19 metabolizer status based on *2 genotypes using the common consensus star allele nomenclature as normal metabolizer (G/G), intermediate metabolizer (G/A), and poor metabolizer (A/A), respectively. The phenotype frequency for CYP2C19*2 was 74.5% (G/G), 21.6% (G/A), and 3.9% (A/A). The subjects with the A allele presented ≥235 P2Y12 reaction unit levels, classifying them how poor metabolizer. The prevalence of reduced CLO effectiveness was associated with the presence of CYP2C19*2 polymorphism among Mexican patients. Conclusion: The presence of the CYP2C19*2 allele is related to resistance to the antiplatelet effect of CLO (p = 0.003).

Resumen Objetivo: Los antiplaquetarios orales son clave en la farmacoterapia moderna de las enfermedades aterotrombóticas cardiovasculares. Clopidogrel (CLO) constituye el principal tratamiento preventivo de aterotrombosis (AT). Sin embargo, se ha documentado una considerable variación interindividual en la respuesta a CLO, lo que da como resultado una terapia subóptima y mayor riesgo de efectos adversos en algunos pacientes. La enzima CYP2C19 es la isoforma CYP que activa CLO a su metabolito activo. Se han identificado varios polimorfismos de un solo nucleótido en el gen CYP2C19 como fuertes predictores de respuesta farmacológica alterada a CLO. Al menos 16 variantes se han asociado con cambios en la actividad de CYP2C19. Método: Se reclutaron un total de 102 sujetos con alto riesgo cardiovascular del noreste de México, con dosis de mantenimiento de 75 mg de CLO/día. La reactividad plaquetaria se midió con el ensayo Verify Now P2Y12, la presencia de CYP2C19*2 se identificó mediante polymerase chain reaction en tiempo real. Resultado: Los pacientes fueron clasificados por el estado metabolizador CYP2C19*2 utilizando nomenclatura consenso, como metabolizador normal (G/G), metabolizador intermedio (G/A) y metabolizador pobre (A/A), respectivamente. La frecuencia del fenotipo para CYP2C19*2 fue 74.5% (G/G), 21.6% (G/A) y 3.9% (A/A). Los sujetos con alelo A presentaron ≥235 niveles P2Y12 reaction unit, clasificándolos como metabolizadores deficientes. La prevalencia de eficacia reducida a CLO se asoció con la presencia del polimorfismo CYP2C19*2 en pacientes mexicanos. Conclusiones: La presencia del alelo CYP2C19*2 se relaciona con resistencia al efecto antiagregante plaquetario del CLO (p = 0.003).

Stroke and transient ischemic attacks related to antiplatelet or warfarin interruption / Acidente vascular cerebral e ataques isquêmicos transitórios relacionados à interrupção de antiplaquetários ou varfarina

ABSTRACT Patients on anticoagulant or antiplatelet therapy are often required to discontinue these medications before and during surgical or invasive procedures. In some cases, the patient stops the treatment without medical supervision. These situations may increase stroke risk. Objective To identify the ischemic stroke and transient ischemic attack (TIA) prevalence related to length of time of discontinuation of antiplatelet or vitamin K antagonist therapy, in a group of inpatients from a specialized neurological hospital in Brazil. Methods Cross-sectional, retrospective and descriptive study of stroke inpatients for three years. Medical reports were reviewed to find study participants, stroke characteristics, risk factors, reasons and time of drug interruption. Results In three years, there were 360 stroke and TIA inpatients, of whom 27 (7.5%) had a history of antiplatelet or vitamin K antagonist interruption correlated with the time of the event (81% ischemic stroke, 19% TIA). The median time between antiplatelet interruption and an ischemic event was five days, and 62% of events occurred within seven days after drug suspension. For vitamin K antagonists, the average time to the ischemic event was 10.4 days (SD = 5.7), and in 67% of patients, the time between drug discontinuation and the event was 7-14 days. The most frequent reason for drug suspension was patient negligence (37%), followed by planned surgery or invasive examination (26%) and side effects, including hemorrhage (18.5%). Conclusion Antiplatelet or vitamin K antagonist suspension has a temporal relationship with the occurrence of stroke and TIA. Since these events are preventable, it is crucial that healthcare professionals convince their patients that drug withdrawal can cause serious consequences.

RESUMO Pacientes em terapia anticoagulante ou antiagregante plaquetária frequentemente são solicitados a descontinuar essas medicações antes e durante procedimentos cirúrgicos ou invasivos. Se o paciente interromper tratamento sem supervisão médica, poderá aumentar de risco de acidente vascular cerebral (AVC). Objetivo Identificar prevalência de AVC isquêmico e ataque isquêmico transitório (AIT) associados à descontinuação de terapia antiplaquetária ou coumarínicos em pacientes internados em hospital especializado em atendimento neurológico no Brasil. Métodos Estudo transversal, retrospectivo de três anos, descritivo dos pacientes hospitalizados por AVC. A revisão de relatórios médicos determinou características do AVC, fatores de risco, motivos e tempo de interrupção medicamentosa. Resultados Em três anos, foram internados 360 pacientes por AVC ou AIT; destes, 27 interromperam temporariamente terapia antiplaquetária ou coumarínicos relacionando ao evento (81% acidente vascular cerebral isquêmico, 19% AIT). A prevalência foi de 7,5%. O tempo médio entre interrupção antiplaquetária e evento foi cinco dias, com 62% deles ocorrendo até sete dias após suspensão medicamentosa. Para coumarínicos, o tempo médio foi 10,4 dias (d.p.= 5,7), em 67% dos casos o tempo entre a descontinuação medicamentosa e o evento foi 7-14 dias. O motivo mais frequente para suspensão do medicamento foi negligência do paciente (37%), seguido por cirurgia planejada ou exame invasivo (26%) e efeitos colaterais, incluindo hemorragia (18,5%). Conclusão Suspensão de terapia de antiplaquetários ou coumarínicos tem relação temporal com ocorrência de AVC e de AIT. Esses eventos são passíveis de serem evitados, sendo imprescindível que profissionais de saúde convençam seus pacientes das consequências graves da retirada do medicamento.