Effect of Obesity on Left Ventricular Structure and Myocardial Systolic Function: Assesment by Tissue Doppler Imaging and Strain/Strain Rate Imaging

Abstract

Obesity is associated with heart failure, cardiovascular morbidity, and mortality. A direct effect of weight on left ventricle (LV) structure and myocardial function is not well-established. The aim of our study is to determine the effect of obesity on LV morphology and systolic function by using LV standard Doppler echocardiographic indices, myocardial Doppler imaging and strain/strain rate imaging indices. We studied 33 obese and 34 age, sex-adjusted control subjects who had no other pathological conditions. Standard transthoracic Doppler echocardiographical measurements, reconstructed spectral pulsed wave tissue Doppler velocities, strain and strain rate imaging of six different myocardial regions were obtained. Peak systolic velocity (SR), peak systolic strain (I), peak systolic strain rate (SR) for each region and as a global systolic longitidunal LV function mean of peak systolic strain of six myocardial regions (glsca) were compared. Age, body surface area, blood pressure, and heart rate were comparable between the two groups. Obese subjects had significantly increased LV end-diastolic volume, septal wall thickness, left atrial diameter, and decreased transmitral early to late diastolic velocity ratio. In obese subjects, reconstructed spectral pulsed-wave tissue Doppler analysis showed significantly decreased basal lateral peak systolic (Sm) velocity (6.68 +/- 1.89 vs. 8.08 +/- 2.50, P < 0.05), mid lateral Sm (5.01 +/- 2.17 vs. 6.78 +/- 3.22, P < 0.05). Differences in regional strain rate (mid septal SR, 1.45 +/- 0.23 vs. 1.63 +/- 0.18, P < 0.05), regional strain (basal septum I, 19.13 +/- 3.83 vs. 22.09 +/- 4.60, P < 0.05; mid-septum I, 18.03 +/- 2.91 vs. 20.25 +/- 4.77, P < 0.05; radial I, 27.50 +/- 7.32 vs. 35.53 +/- 9.48, P < 0.05), and global strain (glsca, 19.38 +/- 1.34 vs. 21.24 +/- 2.82, P < 0.05) were identified between obese and the referent subjects. Obesity is associated with morphologic alterations in left ventricle and left atrium and subclinical changes in left ventricle systolic function which can be detected by strain and strain rate imaging even without overt heart disease.