Indexation of left ventricular mass in adults with a novel approximation for fat-free mass.

BACKGROUND: Indexation to fat-free mass (FFM) seems to be the best option for adjusting left ventricular (LV) mass. However, measurements of FFM are frequently not available. OBJECTIVES: To define the relation of FFM with commonly available anthropometric measures in order to derive an approximation formula of FFM that can be used for valid indexation of LV mass. SUBJECTS AND METHODS: A total of 1,371 subjects from a community survey were examined by echocardiography to measure LV mass and by bioelectrical impedance analyses (BIA) for the determination of FFM. An approximation of FFM was generated in a healthy subgroup of 213 men and 291 women by non-linear regression techniques. RESULTS: Compared with body height, height2.0, height2.7, (the superscripts following weight and height are raised powers used as a more appropriate method for indexing LV mass) or body surface area, FFM measured by BIA in the healthy subgroups was best predicted by gender-specific equations of the form: FFM = 5.1 x height1.14 x weight0.41 for men and FFM = 5.34 x height1.47 x weight0.33 for women. In the healthy reference group, indexation of LV mass for BIA-determined FFM and approximated FFM (FFMa), respectively, equally eliminated gender differences in LV mass and markedly reduced the influence of body mass index without affecting the associations between blood pressure and LV mass. Validation of FFMa in two independent population-based samples, aged 52 to 67 years, of the same source population confirmed that LV mass indexed by FFMa produced results that were highly consistent with those obtained with indexation by BIA-determined FFM. CONCLUSIONS: We propose a novel approximation of FFM based on exponentials of body height and weight. It performed well in the indexation of LV mass in middle-aged men and women of this study. Evaluation of the equation in other populations should be awaited before its use is recommended in situations where direct determination of FFM is not possible.

Body composition and prevalence of left ventricular hypertrophy.

BACKGROUND: Fat-free mass (FFM) has been proposed as an optimal normalization of left ventricular (LV) mass to body size. We sought to evaluate the novel FFM-based criteria of LV hypertrophy (LVH). METHODS AND RESULTS: A population sample of 1371 men and women aged 25 to 74 years was examined by echocardiography and bioelectrical impedance analysis. Internal partition values for LVH were generated in a healthy population subgroup on the basis of LV mass divided by FFM and by the traditional indexations to body height, height(2.7), and body surface area. In contrast to the sex-specific criteria required by traditional indexations, the value of LV mass/FFM that divided individuals with and without LVH was identical for men and women (4.1 g/kg). Estimates of LVH prevalence varied significantly by type of indexation used, internally or externally derived cut points, and by population subgroups. Differences were pronounced among hypertensives and the obese. Thus, the application of LV mass/FFM more than halved the risk of LVH in obese versus nonobese women (odds ratio, 2.5; 95% confidence interval, 1.6 to 4.0) compared with criteria based on LV mass/height(2.7) (odds ratio, 5.5; 95% confidence interval, 3.6 to 8.3). Implications among hypertensives were less marked. CONCLUSIONS: Indexation of LV mass to FFM eliminates sex-specific LVH criteria. The proportion of individuals defined as having LVH using the new criteria deviate markedly from traditional indexations. Prospective investigations will be needed to identify the prognostic implications of different indexations, especially in subgroups such as the obese.

The associations of body size and body composition with left ventricular mass: impacts for indexation in adults.

OBJECTIVES: We investigated the relationship between body size, body composition and left ventricular mass (LVM) in adults, and assessed the impact of different indexations of LVM on its associations with gender, adiposity and blood pressure. BACKGROUND: The best way to normalize LVM for body size to appropriately distinguish physiologic adaptation from morbid heart morphology was discussed. METHODS: We undertook a community survey of 653 men and 718 women, aged 25 to 74 years. Lean body mass (LBM) was determined by bioelectric impedance analyses and LVM was assessed by two-dimensional guided M-mode echocardiography. RESULTS: After traditional indexations to body height, body height2.7, or body surface area, men had higher LVM than women (p < 0.001). These gender differences disappeared (p > 0.05) when LVM was indexed to LBM. The type of indexation also modified the strength of the association between adiposity and LVM. The estimated impact of body fat on LVM indexed to LBM was less than half that obtained with traditional indexations. In contrast, the magnitude of the associations of blood pressure with LVM was entirely independent of the type of indexation. CONCLUSIONS: This study showed the prominent influence of body composition on adult heart size. Indexation for LBM removed gender differences for LVM and reduced the impact of adiposity, but left the effects of blood pressure unchanged. We suggest that this approach be used for clinical and research applications.