The impact of body mass index on cardiac structure and function in a cohort of obese patients without traditional cardiovascular risk factors

BACKGROUND: Obesity has been linked with alterations in hemodynamic, autonomic, and hormonal pathways in the body, leading to a spectrum of cardiovascular changes. We sought to evaluate the effects of obesity on structural and functional changes of the heart in the absence of cardiac disease and associated risk factors. METHODS: We identified healthy outpatients without any cardiovascular disease or risk factors from our institution's echocardiography database (2017–2020). Patients were stratified by body mass index (BMI; normal: 18.5–25 kg/m(2); overweight: 25–30 kg/m(2); class 1 obesity: 30–35 kg/m(2); class 2 obesity: 35–40 kg/m(2); class 3 obesity: >40 kg/m(2)). Traditional and advanced echocardiographic parameters of cardiac chamber size and function including left ventricular global longitudinal strain (LV-GLS), left atrial reservoir strain (LASr), and right ventricular free wall strain (RV-FWS) were examined. The optimal cut-off BMI for discriminating LV-GLS (>-17.5%), LASr (<23%), and RV-FWS (>-23%) impairment was calculated using ROC curves. RESULTS: 307 patients were assessed (41.5 ± 13.3yrs; 36.5%male; LVEF 61.3 ± 4.8%). No significant differences in indexed chamber volumes or LVEF were appreciated across BMI groups (p > 0.05 for all). LV-GLS, LASr, and RV-FWS were all significant on one-way ANOVA for differences from the group mean (all p < 0.01). Jonckheere-Terpstra test confirmed a significant trend of lower absolute LV-GLS, LASr and RV-FWS values across the rising BMI groups. On ROC curve analysis, a BMI value of 29.9 kg/m(2), 35.1 kg/m(2), and 37.3 kg/m(2) were associated with LASr (AUC: 0.75), RV-FWS (AUC: 0.72), and LV-GLS (AUC: 0.75) impairment respectively. CONCLUSION: Obesity is linked with subclinical reduction of cardiac function in otherwise healthy subjects without cardiovascular risk factors, with reduction of left atrial function occurring at lower BMI, followed by the right and left ventricular function.