Effects of Non-Alcoholic Fatty Liver Disease on the Inpatient Outcomes of Patients Admitted for Atrial Fibrillation: An Analysis from the National Inpatient Sample Database (NIS 2016–2019)

Background: Non-alcoholic fatty liver disease (NAFLD), which is recognized under the updated nomenclature as Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD), is increasingly prevalent in the United States and worldwide. Emerging evidence links NAFLD to an elevated risk of atrial fibrillation (AF), yet data regarding the impact of NAFLD on inpatient outcomes among patients admitted for AF remain limited. Methods: The National Inpatient Sample (NIS) from 2016 to 2019 was used to identify adult patients with a primary discharge diagnosis of AF (ICD-10: I48.x). Patients with concurrent NAFLD were compared to those without. Multivariable linear and logistic regression analyses were performed, adjusting for age, sex, race, insurance status, and Charlson Comorbidity Index. The primary outcome was inpatient all-cause mortality. Secondary outcomes included length of stay, inflation-adjusted hospital costs, discharge disposition, and in-hospital complications. Results: Of 1,891,479 weighted AF admissions, 13,840 carried a concurrent NAFLD diagnosis. Concurrent NAFLD was associated with longer length of stay (3.99 vs. 3.35 days, p < 0.001) (which is statistically significant though might be clinically insignificant) and higher hospital costs ($13,841.65 vs. $12,154.55, p = 0.046). No significant difference in inpatient mortality was observed. Conclusions: Concurrent NAFLD among AF hospitalizations is associated with greater resource utilization without a significant mortality difference, highlighting the importance of addressing this comorbidity to reduce the economic burden of AF-related hospitalizations.