Application of Allometric Methods for Indexation of Left Ventricular End-Diastolic Volume to Normal Echocardiographic Data and Assessing Gender and Racial Differences.

BACKGROUND

Gender and racial differences in cardiac chamber size are vital to establish normal ranges of cardiac chamber size in healthy subjects. Many studies report either nonindexed raw measurements or measurements indexed to isometric body surface area (BSA) when establishing normal reference values. Other studies advocate allometric indexation for standardization of heart size. We compared several allometric methods on gender and racial differences in left ventricular end-diastolic volume (LVEDV) measured on three-dimensional echocardiography.

METHODS

Three-dimensional echocardiographic LVEDV data from the World Alliance Societies of Echocardiography normal values study were indexed to isometric BSA, BSA1.5, BSA1.8, isometric height, height2.3, height2.9, and estimated lean body mass. Gender, racial, national, and regional differences in indexed and nonindexed LVEDV were assessed using Cohen's d statistic or Cohen's f statistic, according to the number of groups being compared. Cohen's d < 0.20 and Cohen's f < 0.10 were regarded as very small relative magnitudes of difference.

RESULTS

Differences in LVEDV among White, Black, and Asian races were smallest when BSA1.5 or BSA1.8 was used for indexation, followed by estimated lean body mass. LVEDV/BSA1.5 was nearly identical for men and women (very small, d = 0.05). However, both LVEDV/BSA1.5 and LVEDV/BSA1.8 still provided moderate relative magnitudes of difference (f = 0.22-0.37) among geographic regions. Specifically, among Asians, Indians had the smallest LVEDV/BSA1.5 (1.8). Brazilians had the smallest LVEDV/BSA1.5 (1.8) among Whites.

CONCLUSIONS

Gender and racial differences in LVEDV became smaller when LVEDV was indexed to BSA1.5 or BSA1.8. However, differences in LVEDV among nations remain even after applying allometric scaling. This finding suggests that differences in body composition and/or hemodynamics are potentially more important determinants of heart size than race or gender.