AIMS: To study the relationship between subclinical atrial fibrillation (AF) and changes in cognitive function in a large cohort of individuals with stroke risk factors.

METHODS: Individuals with no prior AF diagnosis but with risk factors for stroke were recruited to undergo annual cognitive assessment with the Montreal Cognitive Assessment (MoCA) along with implantable loop recorder (ILR) monitoring for AF for 3 years. If AF episodes lasting ≥6 minutes were detected, oral anticoagulation (OAC) treatment was initiated.

RESULTS: A total of 1194 participants (55.2 % men, mean age 74.5 (±3.9)) had a combined duration of heart rhythm monitoring of ≈1.3 million days. Among these, 339 participants (28.3%) had adjudicated AF, with a median AF burden of 0.072% (0.02, 0.39), and 324 (96%) initiated OAC. When stratifying the participants into AF burden groups (No AF, AFlow (AF burden <0.25%), and AFhigh, (AF burden >0.25%)), only participants in the AFlow group had a decrease in MoCA score over time (p = 0.03), although this was not significant after adjustment for stroke risk factors. A subgroup analysis of 175 participants (14.6%) with a MoCA <26 at three years found no association to AF diagnosis or burden.

CONCLUSIONS: In a high-risk population, subclinical AF detected by continuous monitoring and subsequently treated with OAC was not associated with a significant change in MoCA score over a three-year period.