Effects of isolated obesity on systolic and diastolic left ventricular function

Abstract

Background: Obesity is associated with increased cardiovascular morbidity and mortality. A direct effect of isolated obesity on cardiac function is not well established. Objective: To determine the direct effect of different grades of isolated obesity on echocardiographic indices of systolic and diastolic left ventricular function. Methods: 48 obese and 25 normal weight women were studied. They had no other pathological conditions. Obesity was classed as slight (n = 17; body mass index (BMI) 25–29.9 kg/m²), moderate (n = 20; BMI 30–34.9 kg/m²), or severe (n = 11; BMI ⩾ 35 kg/m²). Echocardiographic indices of systolic and diastolic function were obtained, and dysfunction was assumed when at least two values differed by ⩾ 2 SD from the normal weight group. Results: Ejection fraction (p < 0.05), fractional shortening (p < 0.05), and mean velocity of circumferential shortening (p < 0.05) were increased in slight and moderate obesity. Left ventricular dimensions were increased (p < 0.001) but relative wall thickness was unchanged. No obese patients met criteria for systolic dysfunction. In obese subjects, the mitral valve pressure half time (p < 0.01) and the left atrial diameter (p < 0.001) were increased and the deceleration slope was decreased (p < 0.01); all other diastolic variables were unchanged. No differences were found between obesity subgroups. Subclinical diastolic dysfunction was more prevalent among obese subjects (p = 0.002), being present in two with slight obesity (12%), seven with moderate obesity (35%), and five with severe obesity (45%). BMI correlated significantly with indices of left ventricular function. Conclusions: Subclinical left ventricular diastolic dysfunction is present in all grades of isolated obesity, correlates with BMI, and is associated with increased systolic function in the early stages of obesity.