Abstract
Cardiomyopathy of obesity in adults is characterized by augmented cardiac output but diminished myocardial performance. This study of healthy adolescent females (mean age 13.7 ± 1.9 years) with a wide range of body fat content was designed to assess evidence of cardiomyopathy in obese youth. Thirteen adolescent females with morbid obesity (body mass index >40 kg m—2) underwent evaluation of resting cardiac size and function as well as cardiac functional reserve during a maximal cycle exercise test. Data were combined with that previously published from this laboratory of nonobese and moderately obese teenage girls and then correlated with body mass index as a marker of obesity. At rest, heart size, stroke volume, and cardiac output were directly related to degree of obesity, whereas a negative correlation was observed between ventricular shortening fraction and body mass index (r = -0.47, P < .01). However, no impairment was observed in cardiac functional reserve with exercise. Maximal cardiac output and stroke volume were directly related to body mass index, but no effect of obesity was seen when values were related to body surface area. Subclinical evidence of diminished myocardial contractility was observed in obese adolescent girls, although no negative effect was seen on cardiac responses to exercise.