CYP2C19 LoF (*2-*8, intermediate/poor metabolisers) carriers (n=2144, 28.7%) were more likely to have an ischaemic stroke while on treatment for clopidogrel than patients without CYP2C19 LoF genetic variants (HR 1.53, 95% CI 1.04 to 2.26, p=0.031). Here, CYP2C19 is linked to ischemic stroke.