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

Abstract

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 non-indexed raw measurements or indexation 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 by three-dimensional echocardiography (3DE). 3DE LVEDV data from the World Alliance Societies of Echocardiography (WASE) normal values study were indexed to isometric BSA, BSA1.5, BSA1.8, isometric height, height2.3, height2.9, and estimated lean body mass (ELBM). Gender, racial, national, and regional differences in indexed and non-indexed LVEDV were assessed using Cohen's d or Cohen's f statistics, 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 magnitude of differences. Differences in LVEDV among White, Black, and Asian races were smallest when BSA1.5 or BSA1.8 was used for indexation, followed by ELBM. LVEDV/BSA1.5 was nearly identical for males and females (very small, d = 0.05). However, both LVEDV/BSA1.5 and LVEDV/BSA1.8 still provided moderate relative magnitude of differences (f = 0.22 to 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. 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.