Left ventricular mass: allometric scaling, normative values, effect of obesity, and prognostic performance

Abstract

The need for left ventricular mass (LVM) normalization to body size is well recognized. Currently used allometric exponents to normalize LVM may not account for the confounding effect of sex. Because sex is a strong determinant of body size and LVM, we hypothesized that these are subject to potential bias. We analyzed data from 7528 subjects enrolled in the Asklepios Study (n=2524) and the Multiethnic Study of Atherosclerosis (limited access data set; n=5,004) to assess metric relationships between LVM and body size, generate normative data for indexed LVM, and compare the ability of normalization methods to predict cardiovascular events. The allometric exponent that adequately described the LVM-body height relationship was 1.7 in both studies and significantly different from both the unity and 2.7, whereas the LVM-body surface area relationship was approximately linear. LVM/height(2.7) consistently demonstrated important residual relationships with body height and systematically misclassified subjects regarding the presence of LVH. LVH defined by LVM/height(1.7) was more sensitive than LVM/body surface area to identify obesity-related LVH and was most consistently associated with cardiovascular events and all-cause death. In contrast to current assumptions, LVM/height(2.7) is not an adequate method to normalize LVM for body size. We provide more appropriate normalization methods, normative data by 2D echocardiography and gradient-echo cardiac MRI, and cutoffs for defining LVH, along with prognostic validation data.

Figure 1

Point estimates and 95%Confidence Intervals for allometric powers describing the relationship between LVM and body height (top bars), weight (middle bars) or BSA (bottom bars). The dashed line indicates the first power.

Figure 2

Body height-LVM relationship in Asklepios reference participants assessed with nonlinear regression with and without accounting for the confounding effect of gender. See text for details.

Figure 3

Prevalence of LVH defined by LVM/height^1.7 and LVM/height^2.7 among male(A) and female(B) MESA participants stratified by body height.