Increased Body Mass Index Is Associated with Congestive Heart Failure and Mortality in Adult Fontan Patients

Objective: Obesity affects adults with congenital heart disease (CHD). The effect of an increased body mass index (BMI) with respect to morbidity and mortality has not been evaluated in adults with complex CHD. Our objective was to evaluate the effects of increased BMI on heart failure and mortality in univentricular patients who had undergone Fontan palliation. Methods: A query of Fontan patients' first appointments at the Washington University Center for Adults with CHD between 2007 and 2014 yielded 79 patients. BMI status as normal (<25kg/m²), overweight (≥25, <30kg/m²), and obese (≥30kg/m²) was established at the patient's first appointment. We analyzed demographics, diuretic requirements, New York Heart Association (NYHA) class, and laboratory values using Student's two-sample t-test and Fisher's exact test. Mortality was assessed via survival curves, and hazard ratios were compiled with proportional hazard modeling. Results: The recent average BMI was significantly greater in patients with NYHA classes II-IV (29.3 ± 9kg/m²) compared with asymptomatic patients (24.8 ± 5.1kg/m², P =.006). Additionally, the average BMI of patients with a high diuretic requirement (≥40mg/day IV furosemide equivalent) was obese, at 32.15 ± 9.1kg/m², compared with 25.91 ± 7.3kg/m² for those on no or lower doses of diuretics (P =.009). Eighteen of the 79 patients met an endpoint of death, hospice placement, or cardiac transplant by the study conclusion. Kaplan-Meier analysis from time of first appointment until recent follow-up revealed a significant association between time to combined endpoint and BMI class. Cox proportional hazard modeling with age adjustment yielded a hazard ratio of 3.2 (95% CI 1.096-9.379) for obesity upon first presentation to an adult CHD clinic. Conclusions: In patients with univentricular hearts and Fontan palliation, obesity is associated with symptomatic heart failure and mortality.