Association of fatty liver index with sudden cardiac arrest in young adults

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) contributes to cardiovascular events. Therefore, we aimed to identify the association of MASLD, as indicated by the fatty liver index (FLI), on sudden cardiac arrest (SCA) in young adults. Methods: We analyzed data from adults aged 20–39 years, who underwent health examinations between 2009 and 2012, sourced from the Korean National Health Insurance Service database. The presence of MASLD was determined using the FLI, which was calculated based on an individual's body mass index, waist circumference, gamma-glutamyl transferase and triglyceride levels. The primary outcome was the occurrence of SCA during the follow-up period, until December 2020. Results: Of the total 5,398,082 individuals analyzed, 4,021,056 (74.5 %) had a normal FLI (FLI <30), 837,943 (15.5 %) were within the intermediate range (30–60), and 539,083 (10.0 %) demonstrated a high FLI (≥60). Individuals with a high FLI were older, and comprised a higher proportion of men with hypertension, diabetes mellitus, dyslipidemia, heart failure, and myocardial infarction. During follow-up, SCA occurred in 4255 individuals (0.08 %). The group with a high FLI exhibited an increased incidence (incidence rate, 0.19) and elevated risk of SCA (hazard ratio, 3.04). Adjustment of covariates revealed a 55 % increased risk of SCA in the high FLI group (adjusted hazard ratio 1.55, 95 % confidence interval 1.41–1.70, p < 0.001). Moreover, the influence of a high FLI on SCA risk was more pronounced in women compared to men. Additionally, an increase in relevant cardiometabolic conditions was associated with an elevated risk of SCA. Conclusions: Among young adults, a high risk of MASLD, as indicated by the FLI, revealed an increased risk of SCA. Furthermore, the association of FLI with the risk of SCA varied by sex and cardiometabolic conditions.