Optimizing endovascular therapy for large vessel occlusion using CYP2C19 genotype-guided antiplatelet therapy: a case report

Background: Approximately 60% of East Asians carry one or two CYP2C19 loss-of-function alleles; moreover, these individuals are refractive to clopidogrel treatment because of poor metabolic capacity of CYP2C19. This study aimed to describe the effectiveness of CYP2C19 genotype-guided antiplatelet therapy during endovascular therapy (EVT) for a patient with large vessel occlusion (LVO) due to large artery atherosclerosis (LAA). Case Description: An 80-year-old man with right vertebral artery (VA) occlusion and severe left VA stenosis presented to our hospital with left hemianopia and left hemiparesis. Diffusion-weighted magnetic resonance (MR) imaging revealed high signal intensity in the right thalamus. Additionally, MR angiography showed occlusion in the P2 segment of the right posterior cerebral artery (PCA); accordingly, EVT was attempted. The occlusion of the right PCA was successfully recanalized; however, the left VA stenosis, which was determined to be the cause of thrombosis, recurred even with repetitive angioplasty under the administration of aspirin and clopidogrel. Rapid genotyping for CYP2C19 variants revealed two deficient alleles (*2/*3), which indicated that the patient was a poor metabolizer of clopidogrel. Additional prasugrel administration with subsequent angioplasty and stenting maintained the patency of the left VA during the perioperative period. Conclusions: Genotyping for CYP2C19 variants during EVT for LVO due to LAA may be important for individualized tailored antiplatelet therapy.