Abstract 14813: Insulin Resistances in Patients With Fontan Palliations

Introduction: Patients (pts) with single ventricles who have undergone Fontan palliation are surviving longer and at increased risk for acquired morbidly. Insulin resistance (IR) and abnormal glucose metabolism are known to be predictors of cardiac morbidity and mortality. Limited studies suggest that IR and metabolic syndrome occur in individuals following Fontan palliation. This study aimed to evaluate IR in Fontan pts. Methods: In this prospective, single-center, case-control study, Fontan pts and controls were recruited during clinic or catheterization visits between 6/2021 - 2/2022. Individuals with diabetes mellitus, pregnancy, steroid use, inotropic support, or surgery within the last 6 months were excluded. Control subjects were eligible if they had 2 ventricle circulation and did not have heart failure or systemic illness. Demographic and clinical data were collected via chart review. Fasting serum glucose and insulin were acquired at their visit. Group comparisons were made in IR via natural log-transformed homeostasis model assessment, ln(HOMA-IR), and QUICKI (1/[log(Insulin) + log(Glucose)]), without/with adjusting for age. Results: In total 89 pts (59 Fontan and 30 controls) were included, with median age of 20.2 yrs (interquartile range 15-28.1). Fontan pts showed significant elevation of ln(HOMA-IR) (0.82±0.62 vs 0.24±0.44) and decrease in QUICKI (0.34±0.03 vs 0.37±0.02) compared to controls (both p<.0001); this remained significant even controlling for age (both p≤0.02). Analysis excluding Fontan pts with obesity still showed significant elevation of ln(HOMA-IR) and reduction of QUICKI in Fontan pts compared to controls when adjusting for age (both p<0.05). With older age there was an increase in ln(HOMA-IR) (mean 0.2 in age < 13 yrs vs. 0.53 in age 13-18 yrs vs. 0.78 in ag > 18 yrs, p=0.01). Using a QUICKI < 0.339 defining IR, there was an increase proportion of IR with older age (7% in age < 13 yrs vs. 26% in age 13-18 yrs vs. 48% in age > 18 yrs, p=0.01). Conclusions: Fontan pts had significant elevation in IR compared to controls using standard clinical IR serum testing that was independent of age. Additionally, IR continues to increase with age. Further evaluation is needed to understand risk for IR in pts undergoing Fontan palliation.