Abstract 15395: Left Atrial Enlargement in Obese Infants
Background: Obesity-related Left atrial (LA) enlargement is an independent risk factor for cardiovascular morbidity and mortality in adults. Increased LA size is also observed in obese children, however, there is little information when LA enlargement begins to appear. To clarify this, we assessed the relationship between body mass index (BMI) and LA size and to investigate their relation to left ventricular (LV) geometry and function during infancy.
Methods: Echocardiography with tissue Doppler imaging was performed in 241 infants aged 4 to10 months (BMI 13.9 to 24.0 kg/m2). LA anteroposterior diameter, LV end-diastolic volume, ejection fraction (EF), mass, and mass-to-volume ratio were measured. Transmitral peak flow velocities during early (E) and late diastole (A) and mitral annular myocardial velocities during early (Em) and late diastole (Am) were measured. E/Em was calculated as an index of LV filling pressure. Isovolumic relaxation time (IRT) and tissue Doppler-derived myocardial performance index (MPI) were assessed.
Results: LA diameter, LV end-diastolic volume, and LV mass increased significantly with increasing BMI (r = 0.63, 0.36, and 0.46, p < 0.01, respectively). A weak but significant relationship between BMI and mass-to-volume ratio was observed (r = 0.20, p < 0.01). The increased LV mass-to-volume ratio was due to a greater increase in LV mass to LV end-diastolic volume. There were no significant relationships between BMI and heart rate, systolic blood pressure, EF, E, Em, IRT, and MPI. LA diameter correlated significantly with increasing LV mass (r = 0.63, p < 0.01), E (r = 0.20, p < 0.01), A (r = 0.17, p < 0.05), and Em (r = 019, p < 0.05), but heart rate, systolic blood pressure, EF, Am, E/Em, IRT, and MPI did not change with LA diameter. On multivariate analysis, increased LA size was best predicted by BMI.
Conclusion: Higher BMI is associated with increased LA size even in infants, however, LV functional change is not present yet. Our findings suggest that LA enlargement is not due to reduced LV diastolic function, and may reflect a physiological adaptation of the heart to the obese state. Further studies are needed to determine whether LA enlargement in obese infants is associated with adverse long term outcome.
- © 2013 by American Heart Association, Inc.