Declining Incidence of Atrial Fibrillation–Associated Ischemic Stroke in Auckland, New Zealand (2012 Versus 2021)

Background Atrial fibrillation (AF) is a major cause of ischemic stroke (IS), and this risk can be substantially reduced with oral anticoagulants (OACs). Using the population‐based ARCOS (Auckland Regional Community Stroke) study, we investigated the temporal trends in AF‐associated IS. Methods We analyzed ARCOS IV (March 2011–February 2012) and ARCOS V (September 2020–August 2021). AF‐associated IS incidence was compared using Poisson exact methods. Regional OAC dispensing trends were also evaluated. Propensity score–weighted logistic regression estimated the marginal association between cohort and AF‐associated IS after standardizing for vascular risk factors. Interaction tests were performed for ethnicity, and sex‐specific differences were assessed using heterogeneity testing. OAC‐associated intracerebral hemorrhage rates were also examined. Results Among 1694 (ARCOS IV) and 1982 (ARCOS V) IS cases, the proportion of AF‐associated IS declined from 32.4% to 21.5% (−10.8% [95% CI −13.7 to −8.0], P