Atrial fibrillation incidence and outcomes in two cohorts of octogenarians: LiLACS NZ.

Background: Atrial fibrillation (AF), the most common cardiac arrhythmia in the general population, has significant healthcare burden. Little is known about AF in octogenarians.

Objective: To describe the prevalence and incidence rate of AF in New Zealand (NZ) octogenarians and the risk of stroke and mortality at 5-year follow-up.

Design: Longitudinal Cohort Study.

Setting: Bay of Plenty and Lakes health regions of New Zealand.

Subjects: Eight-hundred-seventy-seven (379 indigenous Māori, 498 non-Māori) were included in the analysis.

Methods: AF, stroke/TIA events and relevant co-variates were established annually using self-report and hospital records (and ECG for AF). Cox proportional-hazards regression models were used to determine the time dependent AF risk of stroke/TIA.

Results: AF was present in 21% at baseline (Māori 26%, non-Māori 18%), the prevalence doubled over 5-years (Māori 50%, non-Māori 33%). 5-year AF incidence was 82.6 /1000-person years and at all times AF incidence for Māori was twice that of non-Māori. Five-year stroke/TIA prevalence was 23% (22% in Māori and 24% non- Māori), higher in those with AF than without. AF was not independently associated with 5-year new stroke/TIA; baseline systolic blood pressure was. Mortality was higher for Māori, men, those with AF and CHF and statin use was protective. In summary, AF is more prevalent in indigenous octogenarians and should have an increased focus in health care management. Further research could examine treatment in more detail to facilitate ethnic specific impact and risks and benefits of treating AF in octogenarians.