How do cardiovascular risk factors and cardiac remodeling type affect left ventricular global longitudinal strain and right ventricular free wall strain in patients with obesity

Background

Obesity, defined by the World Health Organization (WHO) as a BMI greater than 30k g/m2, has reached epidemic proportions worldwide, related to approximately 2.8 million deaths/year as of June 2021. WHO sub-classifies obesity based on BMI in Class 1: 30–34.9 kg/m2, Class 2: 35–39.9 kg/m2, and Class 3: ≥40 kg/m2. This state of increased body weight is associated with an increased risk of cardiovascular disease. Cardiac remodeling can be affected by obesity and/or other cardiovascular risk factors (CVRF) as an adaptive physiological response. The remodeling patterns, Normal Geometry (NG), Concentric Remodeling (CR), Concentric Hypertrophy (CH), and Eccentric Hypertrophy, are classified by changes in Relative Wall Thickness (RWT), ≤ or >0.42, and/or Left Ventricular Mass Index (LVMI g/m2), ≤ or >88 for women and ≤ or >102 for men. Left Ventricular Ejection Fraction (LVEF) can remain within normal limits in patients with obesity with multiple CVRF and cardiac remodeling. Left Ventricular Global Longitudinal Strain (LV-GLS) and Right ventricular free wall strain (RV-FWS) can be useful to detect subclinical myocardial dysfunction. The aim of this study was to evaluate if these strain variables are affected in patients with obesity associated to other CVRF in relation to cardiac remodeling type when compared to controls.

Methods

2859 patients with BMI ≥30 kg/m2 and 2616 normal-weight controls (BMI between 18.5 and 24.9 kg/m2), with normal and abnormal cardiac geometry, and normal ejection fraction by echocardiography performed between 01/01/2008 and 12/31/2018, were compared. Obesity was classified based on the World Health Organization. CVRF included were Hypertension (HTN), Diabetes Mellitus (DM), Dyslipidemia, history of Vascular Event (myocardial infarction and/or stroke), and Obstructive sleep apnea (OSA).

Results

BMI, cardiac geometry, CVRF, and the number of comorbidities independently affected GLS and RV-FWS (Figure 1 and Figure 2). LV-GLS and RV-FWS values [mean (SD)] in obesity classes 1, 2, and 3 were −19 (2.9), −18.9 (2.9), −18.7 (2.9) & −24.2 (5.2), −23.8 (6.2), −24.5 (5.9), respectively. In the control group LV-GLS and RV-FWS values [mean (SD)] were −20.1 (3.0) & −27 (5.6), respectively. CH was associated with the greatest decrease in LV-GLS and RV-FWS in males and females, regardless of BMI (Figure 2). LV-GLS values [mean (SD)] associated to CH for obesity class 1, 2, and 3, and controls in females were −18.4 (3.4), −18 (3.1) −17.6 (3.6), and −17.8 (4), respectively, and for obesity class 1, 2, and 3, and controls in males were −16.1 (3.5), 16.5 (3.2), −14.4 (2.7), and −16.6 (4.7), respectively (Figure 1).

Conclusion

Obesity associated to CVRF and CH have the lowest values of GLS in patients with normal ejection fraction. These values were exceedingly below average compared to other groups. These parameters should be used as reference values for this population.

Funding Acknowledgement

Type of funding sources: None.

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

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, >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<0.05 is considered significant.

Results

The mean age of controls and obese patients' were 50±16 and 57±13.6 years respectively (P<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<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<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<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<0.0001). No significant difference in LV GLS or indexed LV volume was seen across BMI categories within each remodeling pattern (P>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<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

P2447Defining the values of left ventricular ejection fraction, volumes and strain by 2-dimensional echocardiography in subjects with normal cardiac geometry - a single center study

Background

Left ventricular ejection fraction (LVEF), end diastolic, end systolic volumes (EDV, ESV) and global longitudinal strain (GLS) are very important parameters that are frequently reported in cardiology. Normal cardiac geometry was not considered in articles that published normal values. It is important to know normal parameters for population studies. Our hypothesis is to analyze how EF, volumes and GLS may vary by age groups, gender and BMI in a population with normal cardiac geometry.

Purpose

To define the values in EF, volumes and GLS measurements in a healthy population with normal cardiac geometry stratified by age groups, gender and body mass index (BMI).

Methods

This is a single center retrospective study conducted from 2008 to 2018. We selected 4557 subjects (2605 females, 1952 males) >18 years with ≤ mild valvular heart disease, who underwent 2D-echocardiography (2DE) at Mayo clinic, Rochester. All selected subjects had normal LV geometry (i.e., LV mass index≤88g/m2 in females and ≤102g/m2 in males and relative wall thickness ≤0.42 measured by 2DE) and without any cardiovascular risk factors or structural or functional abnormality determined by 2DE. Based on age groups, gender and BMI, we assessed the variability in volumes indexed to body surface area, EF and GLS by Mean ± SD and two sample t-test.

Results

Mean age was 54±15 years (females = 53±15, males = 56±16), body surface area was 1.9 m2±0.2 (females = 1.8±0.2, males = 2.1±0.2), LV GLS −20.7% ±2 SD (females = −21.2±2, males= −20.2±1.9) ranging −16.1 to −27.6 in both genders (Figure); LVEF by Biplane volume method 62.6% ± 4 SD (females = 63±4.3, males=62±4.5). The end diastolic volume 63.6±11.7 cc/m2 (female = 59.9±10.3, males = 68.1±11.8) and end systolic volume 23.9 cc/m2±5.4 (female = 22.3±4.8, males = 25.9±5.5). LV GLS, Biplane EF values were higher in females and EDV and ESV values were higher in males. LV GLS values decreased with age in females (P<0.0001). While EF increased with age in both genders (P<0.0001), EDV and ESV values decreased with age (P<0.0001). When each gender is sub-divided based on their BMI (<25 and ≥25), GLS, EDV and ESV values were higher in population with BMI <25 (P<0.0001).

Normal geometry variables

Conclusion

To our knowledge, this is the biggest single center study to evaluate LV GLS values, LV EF, ED, ES volumes. These results can be used as reference values in a normal population.

Acknowledgement/Funding

None

P2446Defining values of volumes and longitudinal strain for the different types of left ventricular remodeling patterns in subjects with normal ejection fraction - a single center study

Background

The left ventricle (LV) undergoes different types of remodeling to normalize its wall stress. There has been an increase in the trend in research regarding the process of remodeling but little is known about how LV volumes and global longitudinal strain (GLS) may vary depending upon the type of remodeling.

Purpose

To define the values of LV volumes and GLS in patients with different types of LV remodeling with normal ejection fraction (EF).

Methods

Single center retrospective study conducted from 2008 to 2018. We selected 10,356 subjects >18 years (5808 females, 4548 males) with normal EF and who underwent 2D echocardiography (2DE) at Mayo clinic, Rochester. They were categorized into 4 groups (Figure) i.e., group 1 = normal geometry, group 2 = concentric remodeling, group 3 = concentric hypertrophy, group 4 = eccentric hypertrophy based on their LV mass index (102 g/m2 in males, 88 g/m2 in females) and relative wall thickness (0.42) values measured by 2DE (figure). The patterns of LV GLS, end diastolic and end systolic volumes (EDV, ESV) indexed to body surface area were analyzed in these four groups by gender and body mass index (BMI). Mean±SD, One-way Anova, two sample t-test and Tukey- Kramer HSD were applied.

Results

The mean age of the selected population is 57.9 years ±14.9 (females=57.7±14.7, males=58.2±15.1) and the body surface area of 1.9 m2±0.2 (females=1.8±2 and males=2.1±0.2). The LV GLS values (Figure) of groups 1, 2, 3 and 4 were −20.7, −18.9, −17.5 and −19.9 and their EDV cc/m2 values were 63.6, 58.5, 61.2 and 68.2 respectively. LV GLS and Biplane EF values were higher in females while Biplane EDV and ESV were higher in males. When each gender is sub-divided based on their BMI (<25 and ≥25), the LV GLS, EDV and ESV values were higher in all groups with BMI<25 except in males with concentric remodeling and females with concentric hypertrophy where they were low.

Remodeling distribution

Conclusion

To our knowledge, this is the biggest single center study to evaluate LV GLS and volumes based on type of remodeling by gender and BMI. When compared with normal geometry, LV volumes and GLS values were statistically different among each type of remodeling as well as for gender and BMI. These results can be used as reference values in patient population studies where remodeling is being analyzed in subjects with normal LV EF.

Acknowledgement/Funding

None