Introduction/Aims: Atrial fibrillation (AF) increases the risk of ischemic stroke (IS), however this risk can be mitigated with oral anticoagulants (OAC). International data suggest a decline in AF-associated stroke, coinciding with increased OAC use. Using data from the Auckland Regional Community Stroke (ARCOS) study, we investigated the AF-associated stroke trend in Auckland, New Zealand.
Methods: We analysed grouped data from ARCOS IV (March 2011–Feb 2012) and ARCOS V (September 2020–August 2021), a long-running, population-based stroke registry. AF-associated incident IS and antithrombotic use were compared using statistical tests for categorical data.
Results: We identified 1,694 and 2,029 ischaemic stroke (IS) cases in ARCOS IV and V respectively, including 548 and 420 AF-associated strokes. Median age was unchanged (74 vs 80.5 years, p=0.99). The proportion of AF-associated IS declined from 32.4% to 20.7% (absolute reduction 11.7%, 95% CI: 8.8–14.5, p<0.0001), accompanied by increased OAC use (+29.2%, 95% CI: 23.5–35.0) and decreased antiplatelet use (−30.6%, 95% CI: 24.8–36.4); both p<0.0001. On subgroup analysis, the relative stroke risk reduction was greater in females (−16%) than males (−7.2%), with interaction analysis showing an additional 32% relative risk reduction in females (p=0.01). Based on Auckland census data, the crude incidence of AF-related IS fell from 39 to 25 per 100,000.
Conclusion: AF-associated incident IS declined in Auckland between the two periods, coinciding with increased OAC use. These findings highlight improvements in stroke prevention but warrant further investigation into demographic shifts in AF-related stroke.