Defining echocardiographic reference values of LV volume indices and biventricular strain in obese patients with normal ejection fraction in different cardiac remodeling patterns – a single center study
Authors: Badawy M , Jadav R , Anastasius M , Jain V , Zahid A , Thaden J , Pislaru S , Pellikka P , Kane G , Villarraga H 
Published: November 2020

Abstract

Background
The left ventricle (LV) in obese patients undergoes different patterns of remodeling in order to normalize wall stress. However, little is known about how LV volume indices, LV global longitudinal strain and right ventricular free wall strain (GLS) vary according to the pattern of LV remodeling.

Aim
To define the echocardiographic reference values of LV volumes and biventricular GLS across the different LV remodeling patterns in obese patients with a preserved ejection fraction.

Methods
2393 adult obese patients (1428 females, 965 males) with a normal ejection fraction who underwent echocardiography from January 2008 to December 2018 were selected. They were categorized according to 4 cardiac remodeling groups defined by LV mass index (102g/m2 in males, 88g/m2 in females) and relative ventricular wall thickness (0.42): normal geometry (NG), eccentric hypertrophy (EH), concentric remodeling (CR) and concentric hypertrophy (CH). Obese subjects were further categorized by BMI class (30–35, 35–40, &gt;40 kg/m2). Obese subjects were gender matched to controls with a normal BMI (18.5–25 kg/m2) and normal cardiac geometry. Mean ± SD, One-way Anova and Tukey- Kramer HSD were applied. P&lt;0.05 is considered significant.

Results
The mean age of controls and obese patients' were 50±16 and 57±13.6 years respectively (P&lt;0.0001). LV GLS for controls compared to obese subjects with NG, EH, CR and CH was −21.1±2 vs. −20.2±1.9, −19.6±2.8, −18.5±2.9, −17.5±3.4 respectively (p&lt;0.0001 for all), and for RV GLS it was −27.9±4 vs −26.7±3.9, −25.1±5, −23.5±5.5, −24.1±5.2 respectively (p&lt;0.01 for all, except for NG where p=0.2). The distribution of LV indices according to cardiac remodeling subtypes is shown in the figure. Indexed end diastolic and end systolic volumes were smaller in NG, CH and CR compared to controls (p&lt;0.001 for each respectively). LV GLS and ejection fraction were higher in females, while indexed LV volumes were higher in males within each remodeling category (P&lt;0.0001). No significant difference in LV GLS or indexed LV volume was seen across BMI categories within each remodeling pattern (P&gt;0.05). Obese subjects with CH had the highest incidence of the cardiovascular risk factors hyperlipidemia, hypertension and history of myocardial infarction or stroke, compared to those with other remodeling patterns (p&lt;0.0001 for each, vs. NG, EH and CR).

Conclusion
To our knowledge, this is the largest study to define LV volumes and left and right ventricular GLS according to LV remodeling pattern and BMI category. The Lowest GLS was noted in CH. Ejection fraction was similar across the LV remodeling patterns. There were no differences in GLS and LV indexed volumes across BMI categories within each remodeling group. These results can be applied as a reference values for the obese population with a normal LV ejection fraction.

Funding Acknowledgement
Type of funding source: None