P1514 Increased myocardial oxygen demand is associated with impaired left ventricular strain in patients with morbid obesity referred for bariatric surgery

Abstract

Abstract Background Obesity predisposes for left ventricular (LV) hypertrophy and systolic dysfunction. Higher myocardial oxygen demand in LV hypertrophy is associated with higher risk for cardiovascular events, while the association with LV systolic function has been less explored. Purpose To assess the association of myocardial oxygen demand with LV systolic function in morbidly obese subjects without known heart disease. Methods Clinical and echocardiographic data from 110 obese subjects referred for gastric bypass surgery (mean age 42 ± 11 years, 74% women, mean body mass index [BMI] 41.9 ± 4.8 kg/m², 33% with hypertension, 15% with diabetes) in the prospective FatWest (Bariatric Surgery on the West Coast of Norway) study was used. LV function was assessed by ejection fraction (EF) by Simpson"s biplane method and endocardial global longitudinal strain (GLS) by 2D vector velocity imaging using a 16-segment model (Image Arena 4.6, Tomtec, Unterschleissheim, Germany). Myocardial oxygen demand was estimated from LV mass - wall stress - heart rate product according to a previously validated formula. Results Myocardial oxygen demand was higher in men (1884 vs. 1579 x 10³ g x kdyne/cm² x bpm, p < 0.05), and associated with higher BMI (r = 0.24) and pulse pressure (r = 0.28), and with lower EF (r = -0.22) and lower GLS (r = 0.26, all p < 0.05). In multiple regression analysis, higher myocardial oxygen demand was associated with lower LV GLS (Beta = 0.21, p < 0.05) independent of age, gender, BMI, pulse pressure, diabetes, and EF (Table). Conclusion In obese patients without known heart disease referred for bariatric surgery, higher myocardial oxygen demand was associated with lower LV systolic function measured by GLS independent of confounders. Covariates of lower GLS in multivariable Variable β correlation coefficient p LV mass - wall stress - heart rate product (g x kdyne/cm² x bpm x 10³) 0.21 0.04 Age (years) -0.12 0.22 Gender 0.34 <0.01 BMI (kg/m²) 0.25 <0.01 Pulse pressure (mmHg) -0.04 0.71 Diabetes -0.17 0.09 LV EF (%) -0.01 0.90