Abstract 13382: Increased Adiposity is Associated With Risk of Adverse Clinical Events in Fontan Patients

Introduction: Increased adiposity and reduced lean mass are prevalent in Fontan patients and could be impactful because of the reliance on the peripheral muscle pump and the importance of favourable pulmonary physiology in univentricular physiology. The current study aimed to determine the impact of body fat and lean mass on the risk of adverse outcomes in Fontan patients. Methods: Patients with dual-energy X-ray absorptiometry (DXA) scans from the Australian and New Zealand Fontan Registry were included; they had been consecutively recruited for 2 previous cohort studies. Regression analysis was used to characterize the association between body composition and the composite endpoint of Fontan failure (which included death, transplantation, New York Heart Association (NYHA) functional class III/IV, protein-losing enteropathy, and plastic bronchitis) and development of moderate or worse ventricular dysfunction. Results: 131 DXA scans were analyzed, with mean follow-up of 2.5 (SD 2.2) years after DXA. Mean body fat percentage (%BF) was 29% (SD 10) with 48% having increased adiposity compared with local reference data. Mean appendicular lean mass index (ALMI) z-score was -1.5 (SD 1.1); one third of patients had skeletal muscle deficiency (defined as ALMI z-score between -1 and -2) and another third had Fontan-associated myopenia (defined as ALMI z-score &lt -2). Nine patients reached the composite endpoint during the follow-up period. Age and %BF were predictors of the endpoint in univariable regression (age: HR 1.09 per year, 95% CI 1.02-1.17, p = 0.01; %BF: HR 1.08, 95% CI 1.01-1.17, p = 0.03). On multivariable regression, %BF remained a significant predictor with every 1% increase conferring an 9% increased risk (HR 1.09, 95% CI 1.00-1.19; p = 0.045). ALMI was not a predictor of the endpoint (HR 1.40, 95% CI 0.71-2.76, p = 0.33). However, all patients who experienced a Fontan failure event (n=4) concurrently had increased adiposity and skeletal muscle deficiency. Conclusions: Increased adiposity is associated with increased risk for adverse clinical outcomes. Appropriate lifestyle interventions to optimise body composition should be an important aspect of routine care in this population.