Abstract Body (Do not enter title and authors here): Background: Obesity is associated with left atrial (LA) and left ventricular (LV) dysfunction, however, there is little information on when left heart structural and functional changes begin to appear. To clarify this, we assessed left heart geometry and function in obese healthy infants.
Methods: Two-dimensional echocardiography was performed in 186 infants aged 4 months. Subjects were divided into 3 groups according to body mass index (BMI): normal (n= 110), <18.0 kg/m²; overweight (n=45), 18 to 19.9 kg/m²; obesity (n=31), ≧20 kg/m². LA volumes (maximum, minimum, and pre-atrial contraction) were measured using speckle tracking echocardiography. LA total emptying fraction, passive emptying fraction, and active emptying fraction were calculated. LV end-diastolic volume, ejection fraction, mass, and mass/volume ratio, mitral annular myocardial velocities during early (Em) and late diastole (Am), and myocardial performance index were assessed.
Results: Results are shown in Table. Systolic blood pressure was significantly higher in the obesity group than in the normal and overweight groups. Compared with the normal groups, LA volumes (maximum, minimum, and pre-atrial contraction), LV end-diastolic volume, and LV mass were significantly higher in the overweigh group and the obesity group. LV mass/volume ratio as an index of LV hypertrophy was significantly greater in the the obesity group than those in the normal groups. Compared with the normal group, LA active emptying fraction as an index of LA pump function was significantly higher in the obesity group. Mitral annular myocardial velocity during late diastole in the obesity groups was significantly higher than that in the normal group. There were no significant differences in ejection fraction, mitral annular myocardial velocity during early diastole, myocardial velocity ratio (Em/Am), and myocardial performance index among the 3 groups.
Conclusion: Infant obesity is associated with left heart chamber enlargement, LV hypertrophy, and increased LA pump function, which may be compensatory. Thus, obesity-related changes in left heart geometry and function begin to appear in infancy. Our data support the importance of preventing obesity from early infancy.