Indexation of left ventricular mass to body surface area and height to allometric power of 2.7: is the difference limited to obese hypertensives?

Abstract

Whether left ventricular mass (LVM) should be normalized to different indexes in relation to body size is still debated. We sought to evaluate the prevalence of left ventricular hypertrophy (LVH) defined by different indexation criteria in a cohort of hypertensive subjects categorized according to body mass index (BMI). A total of 2213 essential hypertensive subjects included in the Evaluation of Target Organ Damage in Hypertension (ETODH) were divided in three groups according to BMI thresholds (o25, 25-29.9 and X30 kg m À2 ). All patients underwent extensive investigations including quantitative echocardiography. LVH was defined as an LVM index equal to or higher than (1) 125 g m À2 in men and 110 g m À2 in women, (2) 51 g m À2.7 in men and 47 g m À2.7 in women. Overall, 687 out of 2213 patients (31.0%) were found to have LVH when LVM was indexed to body surface area (BSA) and 1030 (46.5%) when indexed to height 2.7 . A total of 845 patients (38.2%) had normal BMI, 954 patients (43.1%) were overweight and 414 (18.7%) were obese. Prevalence rates of LVH in the three groups were 25.1, 31.6, 41.2% by indexation to BSA and 29.9, 50.5, 71.8% by indexation to height 2.7 , respectively. LVM indexed to BSA markedly underestimates LVH prevalence in obese as well as overweight hypertensive patients. To avoid a systematic misclassification of cardiovascular risk, LVM should be routinely indexed to height 2.7 in overweight and obese patients representing a large percentage of the hypertensive population.

Improving cardiovascular risk stratification in essential hypertensive patients by indexing left ventricular mass to height2.7

“…!51/47 g/m 2.7 vs. !125/110 g/m 2 ) in a cohort of 2213 treated hypertensive patients categorized into three groups according to BMI (<25, 25-29.9 and !30 kg/m 2 ). We found that a stepwise increase in LVH prevalence occurred from normal to overweight and obese hypertensive patients when LVM was normalized to height 2.7 , whereas this trend was much less evident when LVM was indexed to BSA [10]. It should be pointed out that no significant differences in the prevalence of LVH defined by either criteria were observed in the lean hypertensive group.…”

“…This calculation, however, has major mathematical limitations, as the three-dimensional variable LVM is divided by the twodimensional variable BSA and a geometric relationship exists between the two variables [8]. LVM indexed to BSA has been documented to markedly underestimate LVH prevalence in obese individuals, a condition that is more precisely identified by LVM indexed to height to allometric power of 2.7 [9,10].…”

Left-ventricular hypertrophy and obesity

“…This latter criterion has been shown to provide the highest LVH prevalence rates; findings from population-based studies [40,41] and hypertensive cohorts [42] have shown that left-ventricular mass normalized to height to allometric signals identifies a higher portion of patients with LVH, as compared to BSA. In a previous analysis of 2213 treated hypertensive patients, we found that LVH defined by leftventricular mass/h 2.7 was more prevalent than that defined by left-ventricular mass/BSA (46 versus 31%); the corresponding figures in obese individuals were 71 and 40%, respectively [43]. Notably, recent findings show that LVH defined by left-ventricular mass/height 1.7 is more sensitive than left-ventricular mass/BSA or left-ventricular mass/ heght 2.7 in identifying obesity-related LVH and is more consistently associated with cardiovascular events and all-cause death [44].…”

Impact and pitfalls of scaling of left ventricular and atrial structure in population-based studies

“…First, ratiometric indexing to BSA that is usually performed, may not be always appropriate, for instance, for linear dimension, such as left ventricular end-diastolic diameter (LVEDD). Second, previous studies have already addressed issue of left ventricular mass (LVM) indexing [4][5][6][7][8][9], but appropriate scaling and normative values of LVEDD, left ventricular end-diastolic volume (LVEDV), and left atrial volume (LAV) are not as well established [10]. Third, although women and men have different body composition, in practice, we still use the same thresholds for definition of left heart enlargement.…”