Increased Body Mass Index and Ventricular Cardiac Magnetic Resonance Characteristics in Adults With Fontan...

In structurally normal hearts, increased body mass index (BMI) is associated with larger ventricular mass and volume, however, this association has yet to be described in adult Fontan patients.

This study evaluates the relationship of increased BMI and ventricular characteristics by cardiac magnetic resonance imaging (CMR) in a multi-institutional adult Fontan population.

We conducted a multicenter, cross-sectional study using the Fontan Outcomes Registry using CMR Examinations. Fontan patients with CMR at ≥16 years of age were included. The primary independent variable was BMI and dependent variables included CMR characteristics, hemodynamics by cardiac catheterization, and clinical outcomes. Multivariable models for CMR characteristics were additionally created. Analyses were stratified by ventricular morphology.

In total, 983 patients were included with 47% morphologic left ventricle (MLV) and 36% morphologic right ventricle. The median age at CMR was 21.9 years. Thirty-nine percent were overweight or obese. Increased BMI was associated with significantly higher end-diastolic volume and ventricular mass (P < 0.001 for each). In multivariable analysis, compared to normal weight, end-diastolic volume and ventricular mass were significantly elevated for obese patients (+18.0 mL; 95% CI: 8.3-27.7; P < 0.001 and + 19.1 g; 95% CI: 8.7-29.6; P < 0.001, respectively). Median ventricular end-diastolic pressure and Fontan pressure were significantly elevated with increased BMI category (P = 0.006 and P = 0.004, respectively). Stratified by ventricular morphology, similar findings were observed in MLV but not morphologic right ventricle.

Ventricular adaptations in volume and mass incurred by exposure to Fontan circulation are compounded by increased BMI. Obesity may disproportionately affect ventricular volume, mass, and hemodynamics in MLV.