Ambulatory systolic blood pressure and obesity are independently associated with left ventricular hypertrophic remodeling in children

Abstract

Background: Children with obesity have hypertrophic cardiac remodeling. Hypertension is common in pediatric obesity, and may independently contribute to hypertrophy. We hypothesized that both the degree of obesity and ambulatory blood pressure (ABP) would independently associate with measures of hypertrophic cardiac remodeling in children.

Methods: Children, aged 8-17 years, prospectively underwent cardiovascular magnetic resonance (CMR) and ABP monitoring. Left ventricular (LV) mass indexed to height^2.7 (LVMI), myocardial thickness and end-diastolic volume were quantified from a 3D LV model reconstructed from cine balanced steady state free precession images. Categories of remodeling were determined based on cutoff values for LVMI and mass/volume. Principal component analysis was used to define a "hypertrophy score" to study the continuous relationship between concentric hypertrophy and ABP.

Results: Seventy-two children were recruited, and 68 of those (37 healthy weight and 31 obese/overweight) completed both CMR and ABP monitoring. Obese/overweight children had increased LVMI (27 ± 4 vs 22 ± 3 g/m^2.7, p < 0.001), myocardial thickness (5.6 ± 0.9 vs 4.9 ± 0.7 mm, p < 0.001), mass/volume (0.69 ± 0.1 vs 0.61 ± 0.06, p < 0.001), and hypertrophy score (1.1 ± 2.2 vs -0.96 ± 1.1, p < 0.001). Thirty-five percent of obese/overweight children had concentric hypertrophy. Ambulatory hypertension was observed in 26% of the obese/overweight children and none of the controls while masked hypertension was observed in 32% of the obese/overweight children and 16% of the controls. Univariate linear regression showed that BMI z-score, systolic BP (24 h, day and night), and systolic load correlated with LVMI, thickness, mass/volume and hypertrophy score, while 24 h and nighttime diastolic BP and load also correlated with thickness and mass/volume. Multivariate analysis showed body mass index z-score and systolic blood pressure were both independently associated with left ventricular mass index (β=0.54 [p < 0.001] and 0.22 [p = 0.03]), thickness (β=0.34 [p < 0.001] and 0.26 [p = 0.001]) and hypertrophy score (β=0.47 and 0.36, both p < 0.001).

Conclusions: In children, both the degree of obesity and ambulatory blood pressures are independently associated with measures of cardiac hypertrophic remodeling, however the correlations were generally stronger for the degree of obesity. This suggests that interventions targeted at weight loss or obesity-associated co-morbidities including hypertension may be effective in reversing or preventing cardiac remodeling in obese children.

Keywords: Ambulatory blood pressure monitoring; Cardiovascular magnetic resonance; Hypertension; Pediatric obesity; Ventricular remodeling.

Fig. 1

Three-dimensional left ventricular (LV) endocardial and epicardial surfaces (d) were reconstructed using a stack of short-axis bSSFP images (a), a two-chamber view (b), and a four-chamber view (c)

Fig. 2

Principal component analysis (PCA) was used to represent left ventricular (LV) concentric hypertrophy. LV remodeling types were determined using previously defined cutoff values of LV mass index (LVMI) and mass/volume ratio (a). LVMI and mass/volume ratio were normalized by subtracting the mean and divided by the standard deviation derived from the healthy controls, and then hypertrophy scores were defined as the projections (red dot) along the 1st principal component direction using PCA (b)

Fig. 3

A representative example of LV remodeling (wall thickening) from an obese male with concentric hypertrophy compared to an age-matched healthy male

Fig. 4

24 h systolic blood pressure is associated with left ventricular mass index (LVMI), however, obesity independently contributes to increased LVMI