STEATOTIC liver disease (SLD), defined by hepatic fat in more than 5% of hepatocytes, encompasses metabolic dysfunction-associated SLD (MASLD), metabolic dysfunction with alcohol-related liver disease (MetALD), alcohol-associated liver disease (ALD) and other aetiologies.
Metabolic dysfunction, a hallmark of MASLD and MetALD, is linked to cardiovascular disease and may contribute to arrhythmogenesis. Atrial fibrillation (AF) is a common symptomatic arrhythmia worldwide and recent attention has focused on modifiable cardiometabolic and behavioural risk factors, notably obesity, insulin resistance and alcohol use. Clusters of cardiometabolic abnormalities strongly associate with AF development, and meta-analyses demonstrate a dose-dependent relationship between habitual alcohol intake and AF. Against this background, SLD subtypes that reflect differing degrees of metabolic dysfunction and alcohol exposure could plausibly carry variable AF risks.
This nationwide South Korean cohort study examined over six million young adults aged 20–39 years to assess new-onset AF according to contemporary SLD subtypes. Overall, SLD was associated with a significantly higher incidence of AF than absence of SLD, and the adjusted hazard ratios rose progressively from MASLD to MetALD and were highest in ALD. The association persisted after adjustment for confounders and was more pronounced in those aged 30–39 years and in obese individuals, suggesting cumulative cardiometabolic burden and obesity amplify arrhythmogenic potential.
Biological mechanisms plausibly linking SLD and AF include chronic low-grade inflammation, oxidative stress, mitochondrial dysfunction and increased epicardial adipose tissue, promoting atrial remodelling. Alcohol may further exacerbate risk via direct electrophysiological effects, autonomic imbalance and promotion of fibrosis, which helps explain the particularly high risk observed in ALD and MetALD groups. Male predominance in ALD and MetALD likely reflects gender differences in alcohol use.
Strengths of the study include its population coverage via the Korean NHIS, while limitations include reliance on the fatty liver index and claims data, and the observational design which precludes causal inference. Nevertheless, findings indicate SLD is a modifiable risk marker for AF in young adults. Early identification and management of hepatic steatosis, weight reduction and alcohol harm-reduction strategies may therefore be important to reduce future AF burden and associated cardiovascular complications and improve cardiovascular health across the life course urgently.
Reference
Park J et al. Associations between steatotic liver disease subtypes and incident atrial fibrillation in young adults: a nationwide cohort study. Cardiovasc Diabetol. 2025;24(1):348.
