A comparison of the effects of indexation on standard echocardiographic measurements of the left heart in a healthy multi-racial population.

Accurate reference ranges for measurements from echocardiography rely on an understanding of the distribution of each measurement in the diverse, multi-racial world population. The aim of this study was to determine the influence of gender, age and ethnicity on common echocardiographic measures of the left heart, and to evaluate the effect of different methods of indexation on measurements from healthy, non-Caucasian populations. Standard echocardiographic measurements of left heart size and left ventricular mass (LVM) were assessed in 341 healthy volunteers. Indexation was performed using height, body surface area, and fat free mass (FFM). Quantile regression was used to derive age-adjusted values at the 5th, 50th and 95th‰ of each measurement, by gender, within Caucasians. The effect of indexation method across ethnic groups could then be compared. Indexation of m-mode dimensions may overcompensate for body size, resulting in people of smaller build (women and those of South or East Asian descent) developing higher indexed values than those of larger build (men and people of Maori or Pacific descent). Indexation of 2D volumes by any method improves the integration of values across ethnic groups, with FFM yielding the greatest integration. LVM increases with age, suggesting that the static reference values currently recommended for this measurement may not be appropriate. There are important differences in the distribution of measurements of left heart size by gender, ethnicity and age.