Longitudinal study of anthropometry in Fontan survivors: Pediatric Heart Network Fontan study

Abstract

Background: Growth abnormalities in single-ventricle survivors may reduce quality of life (QoL) and exercise capacity.

Methods: This multicenter, longitudinal analysis evaluated changes in height and body mass index (BMI) compared to population norms and their relationship to mortality, ventricular morphology, QoL, and exercise capacity in the Pediatric Heart Network Fontan studies.

Results: Fontan 1 (F1) included 546 participants (12 ± 3.4 years); Fontan 2 (F2), 427 (19 ± 3.4 years); and Fontan 3 (F3), 362 (21 ± 3.5 years), with ~60% male at each time point. Height z-score was -0.67 ± -1.27, -0.60 ± 1.34, and- 0.43 ± 1.14 at F1-F3, lower compared to norms at all time points (P ≤ .001). BMI z-score was similar to population norms. Compared to survivors, participants who died had lower height z-score (P ≤ .001). Participants with dominant right ventricle (n = 112) had lower height z-score (P ≤ .004) compared to dominant left (n = 186) or mixed (n = 64) ventricular morphologies. Higher height z-score was associated with higher Pediatric Quality of Life Inventory for the total score (slope = 2.82 ± 0.52; P ≤ .001). Increase in height z-score (F1 to F3) was associated with increased oxygen consumption (slope = 2.61 ± 1.08; P = .02), whereas, for participants >20 years old, an increase in BMI (F1 to F3) was associated with a decrease in oxygen consumption (slope = -1.25 ± 0.33; P ≤ .001).

Conclusions: Fontan survivors, especially those with right ventricular morphology, are shorter when compared to the normal population but have similar BMI. Shorter stature was associated with worse survival. An increase in height z-score over the course of the study was associated with better QoL and exercise capacity; an increase in BMI was associated with worse exercise capacity.

Figure 1:

Height Comparison of the Fontan Cohort with the Normal Population. (A) Heights of male and female Fontan participants were lower than CDC norms. (B) Average height z-score of the Fontan cohort was below normal (Z=0) across ages and study time-points. BMI: The mean BMI z-score was −0.05±1.00, −0.059±1.26, and −0.15±1.27 for F1, F2 and F3, respectively. BMI z-scores for both male and female Fontan participants, age ≤ 20 years, were not significantly different from the normal population (Figure 2). In adult participants >20 years at F2 and F3, 41% (CI 34–48%) of the males and 33% (CI 26–41%) of the females were overweight or obese. The prevalence of overweight and obesity in adults, age > 20 years, in the study cohort was lower than the general US population (p<0.001) (Figure 3).

Figure 2:

BMI Comparison of the Fontan Cohort with the Normal Population. (A) BMI of male and female Fontan participants was similar to CDC norms. (B) Average BMI z-score (for age≤20 years) of the Fontan cohort was similar to normal (Z=0) across ages and study time-points.

Figure 3:

Percent of the Fontan Cohort Overweight/Obese at F2 and F3, compared to Population Norms among participants > 20 years. There were significantly fewer overweight/obese adult Fontan subjects compared to NHANES norms. * p<0.05

Figure 4:

Comparisons of Height and BMI z-scores by Ventricular Morphology-Fontan participants with RV dominant morphology compared to left and mixed ventricular morphologies had lower height z-score (p=0.007: −0.35±0.11 RV vs. LV; −0.28±0.15 RV vs. mixed), but did not differ by BMI z-score (p=0.79: −0.04±0.11 RV vs. LV; −0.05±0.14 RV vs. mixed).

Figure 5A and 5B:

Comparisons of Height and BMI z-scores for Fontan Survivors vs. Non-survivors (N=32 non-survivors). Odds of death were lower with increasing height z-score: p<0.001; OR=0.56 [95% CI: 0.46, 0.68], but did not change with increasing BMI z-score: p=0.11; OR=0.82 [95% CI: 0.64, 1.05]. All 32 non-survivors had data on height and BMI at F1. Of the 16 deaths after F2, 14 participants had data on height and BMI, with 4 of these participants over age 20. Of the 6 deaths after F3, 5 participants had data on height and BMI at F3; all of them were over age 20.