Incident cardiac arrhythmias associated with metabolic dysfunction-associated steatotic liver disease: a nationwide histology cohort study.

BACKGROUND: Prior studies suggest a link between metabolic dysfunction-associated steatotic liver disease (MASLD) and incident arrhythmias, including atrial fibrillation (AF). However, robust data are lacking from cohorts with liver histology, which remains the gold standard for staging MASLD severity.

METHODS: This population-based cohort included all Swedish adults with histologically-confirmed MASLD and without prior cardiac arrhythmias (1966-2016; n = 11,206). MASLD was defined from prospectively-recorded histopathology, and characterized as simple steatosis, non-fibrotic steatohepatitis (MASH), non-cirrhotic fibrosis, or cirrhosis. MASLD patients were matched to ≤ 5 controls without MASLD or arrhythmias, by age, sex, calendar year and county (n = 51,856). Using Cox proportional hazards modeling, we calculated multivariable-adjusted hazard ratios (aHRs) for incident arrhythmias (including AF, bradyarrhythmias, other supraventricular arrhythmias, ventricular arrhythmias/cardiac arrest).

RESULTS: Over a median follow-up of 10.8 years, incident arrhythmias were confirmed in 1351 MASLD patients (10.3/1000 person-years [PY]) and 6493 controls (8.7/1000PY; difference = 1.7/1000PY; aHR = 1.30, 95%CI 1.22-1.38), and MASLD patients had significantly higher rates of incident AF (difference = 0.9/1000PY; aHR = 1.26, 95%CI 1.18-1.35). Rates of both overall arrhythmias and AF were significantly elevated across all MASLD histological groups, particularly cirrhosis (differences, 8.5/1000PY and 5.3/1000PY, respectively). In secondary analyses, MASLD patients also had significantly higher rates of incident ventricular arrhythmias/cardiac arrest (aHR = 1.53, 95%CI 1.30-1.80), bradyarrhythmias (aHR = 1.26, 95%CI 1.06-1.48), and other supraventricular arrhythmias (aHR = 1.27, 95%CI 1.00-1.62), compared to controls.

CONCLUSIONS: Compared to matched controls, patients with biopsy-confirmed MASLD had modest but significantly higher incidence of cardiac arrhythmias, including AF, bradyarrhythmias, other supraventricular arrhythmias and ventricular arrhythmias/cardiac arrest. Excess risk was observed across all stages of MASLD and was highest with cirrhosis.