Prevalence and Factors Associated with Echocardiographic Abnormalities in Children with Sickle Cell Disease; Results from the Displace Study

Introduction

Cardiopulmonary complications remain a leading cause of morbidity and mortality in adults with sickle cell disease (SCD) particularly for people with sickle cell anemia (SCA) who have lower hemoglobin and higher baseline hemolysis. Many cardiovascular complications are not identified until adulthood when patients have developed irreversible pathology. Previous studies have suggested that SCD-specific therapies like hydroxyurea (HU) may be beneficial in reducing the hemolysis associated vascular dysfunction and reducing cardiopulmonary complications. This study describes the prevalence of and factors associated with left ventricular hypertrophy (LVH), left atrial dilation and high tricuspid regurgitant jet velocity (TRJV) in children with SCA. We also describe the association between patent foramen ovale (PFO) and ischemic stroke in children with SCA.

Method

This crossectional study used data collected as part of the Dissemination and Implementation Stroke Prevention Looking at the Care Environment (DISPLACE) study. American society of echocardiography (ASE) guidelines and cutoff values were used to define abnormalities in the echocardiographic variables.

Results

A total of 1414 children were included in the analysis. The median age was 9 years (range 5-12 years) and median hemoglobin of 8.6 g/dl. The most common abnormal findings on echocardiogram was left atrial dilatation (61% of the children), LVH (20% of children) and high TRJV (23% of children). Children with abnormal echocardiographic variables were more likely to have lower hemoglobin level. Children with LVH were more likely to have left atrial dilation, high TRJV and abnormal left ventricular end diastolic diameter (LVIDD). Multivariable analysis of LVH was conducted and included variables: age, sex, hemoglobin, reticulocyte count, treatment with chronic red cell transfusion therapy (CRCT) or hydroxyurea therapy (HU). Baseline hemoglobin levels were associated with the lower odds of having LVH (OR: 0.71, 95% CI: 0.60 - 0.84). The odds of LVH increases for every one-year increase in age (OR: 1.07, 95%CI: 1.02-1.13). Similarly, the odds of LVH was lower among males than females (OR:0.59, 95%CI: 0.38-0.93). The odds of LVH were higher among those on HU compared to no therapy (OR: 1.83, 95% CI: 1.41 - 2.37).

Although not all children had a bubble, study, a total of 90(6.3%) had an identified PFO. We assessed the relationship between PFO and ischemic stroke. 102 (7.2%) of the 1414 children had an ischemic stroke. Out of this 5 (5.6%) had PFO. We also assessed the relationship between PFO and abnormal TCD. 142 (10.0%) of the 1414 had abnormal TCD and only 9 (10%) of the 142 had PFO. There is no evidence that the odds of having stroke was higher among those with PFO compared to those without (OR: 1.49, 95% CI: 0.20- 11.03, p = 0.6994). Similarly, no evidence that the odds of having abnormal TCD is higher among those with PFO compared to those without (OR: 0.85, 95% CI: 0.17- 4.25, p = 0.8463).

Conclusion

Overall results of the study showed echocardiographic abnormalities are common in and occur at an early age in children with SCA. The risk of LVH increases with increasing age and with lower hemoglobin. Further, we found higher use of HU among those with LVH, suggesting that possibly children with more severe disease requiring HU are also at increased risk of cardiopulmonary complications.

Given the fact that high TRJV is an independent risk factor for death in adults with SCD and left atrial dilatation has been shown to be an independent predictor of cardiac events, our data support further investigation into identifying early biomarkers of cardiovascular morbidity in children with SCD.

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