Abstract 14360: Ratiometric and Allometric Relations Between Left Atrial Dimension and Measures of Body Size: the EchoNoRMAL Collaboration
Normalization for body size is an accepted method to compare cardiovascular parameters among subjects with differing body shape. As largely demonstrated for LV mass, normalization should take into account the geometric relations between measures of body size and the parameter to normalize, avoiding a ratiometric approach for measures that cannot be linearly related. Taking advantage of the EchoNoRMAL collaboration, we analysed the relations between maximal left atrial (LA) dimension (LAD) and measures of body size to generate gender-specific normal reference values.
Methods: The EchoNoRMAL database is an individual-person meta-analysis including population-based echocardiographic data from 18 to 80 yr olds (n=23301, 46±16 yrs) free of CV disease. This analysis is restricted to 6869 non-obese European subjects (3310 women) with m-mode LAD and anthropometric measures. We determined sex-specific limits for normalized LAD (LADi) using ratiometric or allometric approaches depending on geometric relationships with height, weight and body surface area (BSA).
Results: Men had slightly greater body mass index, height, and weight than women (all p<0.001). Thus LAD was greater in men (3.6±0.5 cm) than women (3.3±0.5 cm, p<0.001). For normalization, LAD was ratiometrically divided by height (being both linear measures), whereas sex-specific allometric signals (b) were generated for body weight and BSA based on the best-fitting power regression y=axb. As geometrically expected, the b for weight (a 3-dimensional variable) was close to the 0.33 (0.36 in women, 0.41 in men), and the b for BSA (a 2-dimensional variable) was approaching 0.5 (0.55 in women, 0.60 in men for BSA).
Conclusion: Sex-specific reference values of the three measures of LADi were derived (Table).
Table: sex-specific 95th centile of the three measures of LAD index.
- © 2013 by American Heart Association, Inc.