Waist-to-height ratio for the obesity paradox in heart failure: is it a matter of fitness?

This commentary refers to ‘Anthropometric measures and adverse outcomes in heart failure with reduced ejection fraction: revisiting the obesity paradox’, by J. H. Butt et al., https://doi.org/10.1093/eurheartj/ehad083.

The obesity survival paradox has been observed in patients with chronic heart failure (HF) for longer than 20 years.¹ Body mass index (BMI), defined as the body weight (kg) divided by the body height squared (m²), was the mostly used anthropometric measure for the obesity paradox in HF in prior studies.² However, there has been a long-standing debate on whether greater BMI levels serve an appropriate measure for the adiposity in overweight or obesity. The concern was that greater BMI could also reflect greater muscle mass, adequate nutrition status, and superior physical fitness, all which have been identified as prognostic factors for survival in HF.² Moreover, previous studies also revealed conflicting results for the obesity paradox assessed by the adiposity for the risk of mortality in HF.^1,3 Lavie et al.¹ found an inverse association of the total body fat with the mortality risk in HF, while Tsujimoto and Kajio³ and Butt et al.⁴ in this study, respectively, revealed an association of waist circumference (WC) and waist-to-height ratio (WHtR), the commonly used measures for abdominal fat, with the mortality risk in HF. The abdominal pressure could be raised when the lung inflation and the diaphragm descent in those with abdominal obesity during the respiration, possibly leading to a reduced cardiorespiratory fitness (CRF), which may explain the obesity paradox blunted in the present study.⁴

In a sample of 1120 physically fit military personnel,⁵ Pearson correlation test was used to investigate the correlations of BMI, WHtR, and WC with estimated maximal oxygen uptake (VO₂ max, mL/kg/min) in a run test (Table 1 ). In the univariate analysis, WHtR and BMI were negatively associated with VO₂ max (r = 0.11 and 0.07, respectively), whereas WC was not associated with VO₂ max (r = 0.03). However, with adjustments for age, sex, BMI, and WHtR in the multivariable Model 1 analysis, WHtR was negatively associated with VO₂ max (P = .02), whereas the negative association for BMI became not significant (P = .83). In addition, in another multivariable Model 2 analysis with adjustments for age, sex, BMI, and WC, the latter became significantly and negatively associated with VO₂ max (P = .02), whereas the inverse association for BMI became not significant (P = .75). It is similar to the study by Tsujimoto and Kajio³ that WC was not associated with the mortality risk in the multivariable model if BMI was not adjusted simultaneously. Obviously, WHtR, an anthropometric index of body shape, itself and WC as adjusted for the parameter involving the body height (e.g. BMI) were more closely associated with VO₂ max than BMI.

The body shape assessed by WHtR is a crucial factor to affect CRF which could determine the prognosis of HF. Even many years ago, we suggested that the obesity paradox in cardiovascular disease, including coronary heart disease as well as HF, was only noted in those with low CRF.² In our opinion, adequate nutritional support to increase the muscle mass and appropriate physical training to reshape the body, particularly WC reduction in abdominal obesity, and to increase CRF are main strategies for management in systolic HF.

Supplementary data

Supplementary data are not available at European Heart Journal online.

Declaration

Disclosure of Interest

All authors declare no conflict of interest for this contribution.

References