Correlation between Body Mass Index and Left Ventricular Remodeling and Function in Children with Sickle Cell Disease

Background:

Cardiovascular complications play an important role in morbidity and mortality of patients with sickle cell disease (SCD). Historically, patients with SCD were underweight, but due to changes in the diet and advances in therapies there is a trend of increasing BMI, with some patients developing metabolic syndrome (MS). We hypothesized that obesity, MS, and SCD are associated with left ventricular (LV) remodeling and dysfunction and the presence of these conditions may increase the risk of cardiac disease.

Objective:

We aimed to evaluate the association between BMI and LV remodeling and dysfunction in pediatric patients with SCD, as well as the association with laboratory markers and clinical outcomes.

Methods:

We performed a retrospective study that included patients 10 to 22 years old with SCD followed at St. Christopher's Hospital for Children. Data collected included BMI, markers of MS, hemolysis, and inflammation, clinical outcomes and 2D and Doppler echocardiographic parameters. Echocardiogram parameters included those of cardiac structure, geometry, systolic function, and diastolic function. Analysis of variance (ANOVA) tests were performed to examine the differences between biomarkers and various weight categories. Pearson correlations were calculated to evaluate associations of BMI percentile with biomarkers and LV remodeling variables. A chi square test was used to assess differences in geometry by weight categories. Differences in BMI percentile associated with MS status was explored with a T-Test. ANOVA was used to assess differences in mean LV remodeling and functional variables associated with the various weight categories.

Results:

Demographic and laboratory data was collected on all 139 patients who met inclusion criteria, 35 had both pediatric cardiology evaluation and complete echocardiography. Of the 139 patients, 17 (12%) were obese, with 5 of them meeting the criteria for MS as defined by the International Diabetes Federation. Blood pressure was found to be significantly higher in obese patients when compared to non-obese patients (p = 0.026). Hemoglobin was statistically different among weight groups (underweight, normal weight, overweight, obese), with higher mean values being seen in the overweight and obese groups (p = 0.006). No significant correlations were found between cardiac biomarkers, BMI percentile and MS. In 35 patients with echocardiographic data, BMI percentile was positively correlated with relative wall thickness and negatively correlated with peak early LV filling and peak early LV filling/septal annuli early peak (E/Ea) velocities. Relative wall thickness was also positively associated with age. Partial correlations of BMI percentile with these variables were therefore calculated and remained significant in the same directions: Relative wall thickness (r = 0.345, p = 0.046), peak early LV filling velocity (r = -0.473, p = 0.011) and E/Ea (r = -0.415, p = 0.015). E/Ea was also significantly associated with weight category, with higher values in the normal and underweight groups (p = 0.020). Weight category and geometry were not significantly related.

Conclusions:

Obese patients were found to have significantly higher blood pressures and higher BMI percentiles were associated with LV remodeling, contributing to the risk of cardiac disease. Conversely, higher BMI percentile was associated with lower diastolic function measures (improved LV diastolic function) and the trend of higher mean hemoglobin values. This study suggests a complex relationship between BMI, hemoglobin and cardiovascular risks in children with SCD. Further prospective studies with larger sample size are necessary to validate our findings and to develop preventive strategies for cardiovascular risks in SCD.