Abstract Body (Do not enter title and authors here): Background: Biomarkers measured in plasma reflecting cardiorenal dysfunction and inflammation are associated with clinical outcomes in atrial fibrillation (AF). We recently showed an association between the plasma level of the neuronal biomarker neurofilament light chain (NFL) and subsequent stroke and death in patients with AF not receiving oral anticoagulation (OAC).

Purpose: We aimed to compare NFL with other circulating neuro-specific biomarkers, specifically glial fibrillary acidic protein (GFAP), tau, and ubiquitin carboxy-terminal hydrolase L1 (UCHL1), concerning associations with the risk of stroke and other outcomes in patients with AF.

Methods: Concentrations of NFL, GFAP, tau, and UCHL1 were determined with Single Molecule Array (Simoa®) in plasma samples obtained at baseline from 967 patients with AF randomized to aspirin in the ACTIVE A trial. Median follow-up was 3.6 years. Associations between baseline biomarker concentrations, clinical variables (age, sex, body mass index, smoking, alcohol consumption, type of AF, cardiac rhythm at baseline, heart failure, hypertension, diabetes, prior stroke/transient ischemic attack, peripheral arterial disease, and myocardial infarction), and outcomes (ischemic stroke, cardiovascular and all-cause death) were analysed with Cox regression, adjusting for clinical variables and other biomarkers.

Results: Increasing age and female sex were associated with elevated levels of all four biomarkers. Plasma levels of NFL were positively correlated with those of GFAP (r=0.67, p<0.001), tau (r=0.12, p<0.001), and UCHL1 (r=0.37, p<0.001). NFL was independently associated with subsequent ischemic stroke (HR 1.27, 95% CI 1.03–1.56 for a doubling of NFL), cardiovascular death (HR 1.37, 95% CI 1.13–1.64 for a doubling of NFL), and all-cause death (HR 1.46, 95% CI 1.25–1.70 for a doubling of NFL) after adjustment for clinical factors and other biomarkers. In unadjusted analyses, GFAP was associated with ischemic stroke and death; tau and UCHL1 with death only, however, these associations were not significant after adjusting for clinical variables (Table).

Conclusions: In patients with AF not receiving OAC, NFL was independently associated with ischemic stroke and death. Further investigation of NFL and its association with clinical outcomes in patients with cardiovascular disease is therefore warranted.