Metabolic Dysfunction-Associated Steatotic Liver Disease and Outcomes in Atrial Fibrillation.

BACKGROUND: Metabolic dysfunction-associated steatotic liver disease is associated with incident atrial fibrillation, but its prognostic significance in established atrial fibrillation is unclear. We evaluated its association with clinical outcomes. METHODS: We conducted a retrospective cohort study using the TriNetX Research Network. Adults with atrial fibrillation, with or without metabolic dysfunction-associated steatotic liver disease, underwent 1:1 propensity-score matching. Outcomes were assessed for 3 years using Kaplan-Meier and Cox models. RESULTS: The matched cohort included 19,154 patients (9,577 per group). All-cause mortality was similar between groups (HR 0.94, 95% CI 0.85-1.03). Metabolic dysfunction-associated steatotic liver disease was associated with higher risks of major adverse cardiovascular events (HR 1.14, 95% CI 1.09-1.18), heart failure (HR 1.12, 95% CI 1.07-1.18), heart failure with preserved ejection fraction (HR 1.18, 95% CI 1.11-1.25), heart failure with reduced ejection fraction (HR 1.09, 95% CI 1.02-1.17), myocardial infarction (HR 1.16, 95% CI 1.05-1.27), and chronic kidney disease stage 3 or greater (HR 1.12, 95% CI 1.06-1.18). Ischemic stroke risk was similar (HR 1.03, 95% CI 0.94-1.14). CONCLUSIONS: In established atrial fibrillation, concomitant metabolic dysfunction-associated steatotic liver disease was associated with modestly higher cardiovascular and renal morbidity but not mortality or stroke. These observational findings identify a risk marker and do not establish causality.