Left-axis deviation and adiposity: the United States Health and Nutrition Examination Survey

The influence of body fatness on the direction of the electrocardiographic mean frontal plane QRS axis was investigated in a nationally representative population of 6,913 adults aged 25 to 74 years (the U.S. Health and Nutrition Examination Survey). Adiposity was measured as skinfold thickness and the mean frontal QRS axis was determined by computer analysis of limb lead vectors. A significant leftward shift of the mean QRS axis occurred with increasing fatness in both men and women (p less than 0.001) and was independent of age and blood pressure. However, this association was confined to the range of normal QRS axis. The prevalence of left-axis deviation (LAD) (QRS axis of -30 degrees or less) was not higher among those with greater measures of body fatness. There were no significant differences in mean age-adjusted skinfold thickness, height, weight or chest circumference between those with LAD and those with a normal QRS axis. Thus, although the direction of the mean frontal QRS axis is influenced significantly by body fatness throughout the normal QRS axis range, this association is lost as the QRS axis becomes abnormally deviated to the left. An ECG demonstrating LAD obtained from an obese person probably represents a true abnormality and not merely a reflection of adiposity.