Obesity has long been identified as a risk factor for the development of heart failure (HF). However, its prognostic significance in patients with established HF, particularly those with reduced ejection fraction (HFrEF), still needs to be fully understood. There is an emerging concept of an ‘obesity-survival paradox’ in HFrEF patients, where obesity appears to be associated with better survival outcomes.
However, these associations have been based on body mass index (BMI), which has several limitations as a measure of adiposity. Alternative anthropometric indices, such as waist-to-height ratio, may better reflect body fat distribution and have been suggested to replace BMI in evaluating adiposity.
Moreover, the relationship between adiposity and natriuretic peptide levels, one of the most potent predictive variables in HFrEF, further complicates the picture. Although only some studies have accounted for this relationship, it is essential to understand the potential confounding effects on the association between anthropometric indices and outcomes in HFrEF.
A new study published in European Heart Journal has shown that the obesity-survival paradox in patients with heart failure and reduced ejection fraction (HFrEF) disappears when adjusting for other prognostic variables. The study on patients in the PARADIGM-HF trial also found that newer anthropometric indices showed a weaker relationship between adiposity and fatal outcomes than body mass index (BMI) when adjusted for conventional risk variables.
However, these newer indices demonstrated a higher risk of HF hospitalization in patients with greater adiposity, suggesting that they identify pathophysiologic processes not reflected by conventional prognostic variables related to body fat distribution.
A study compared the predictive value of several newer anthropometric indices with BMI in patients with heart failure and reduced ejection fraction. The study aimed to determine the impact on global mortality and morbidity in heart failure. The primary outcome of the study was HF hospitalization or cardiovascular death. The study found an ‘obesity-survival paradox’ related to lower mortality risk in those with a BMI of 25 kg/m2 or more than average weight.
However, this paradox was eliminated after adjustment for other prognostic variables. The study also found that greater adiposity was associated with a higher risk of the primary outcome and HF hospitalization. This was more evident in the waist-to-height ratio. The waist-to-height ratio is a better predictor of the risk of heart failure hospitalization than BMI. The association between anthropometric indices and outcomes was comprehensively adjusted for other prognostic variables, including natriuretic peptides.
A low BMI was associated with a higher risk of death, with a significant excess of non-cardiovascular death rather than cardiovascular death. The relationship between adiposity and health-related quality of life was consistent between BMI and waist-to-height ratio. Both showed a steep decline in health-related quality of life with increasing adiposity.
The findings highlight the importance of promoting weight loss in obese patients with HFrEF, especially as the obesity-survival paradox appears to be an artifact of unadjusted analyses of BMI. However, few randomized controlled trials using dietary and exercise intervention, bariatric surgery, or novel pharmacological therapies have been conducted in patients with HFrEF.
Therefore, efforts to find effective and safe approaches to reducing weight in patients with HFrEF are warranted. The study also highlights the need for more research into using newer anthropometric indices to identify pathophysiologic processes related to body fat distribution.
The study also examined the effect of sacubitril/valsartan, a combination drug used to treat heart failure, according to anthropometric measures. The researchers found that the drug was equally effective in patients with different anthropometric measures, suggesting that the drug can be used regardless of a patient’s body composition. However, the authors note that more research is needed to confirm these findings.
The study’s findings have implications for managing heart failure in patients with different anthropometric measures. Weight loss should be promoted in obese patients with HFrEF, and a newer anthropometric index should be used to identify pathophysiologic processes related to body fat distribution.
However, the study has some limitations, such as the possibility of unmeasured confounding despite adjustment for known variables and the association of abdominal anthropometric measurements with higher measurement errors than BMI. The analyses did not account for any weight or waist circumference changes during follow-up, and the study did not have data on cardiorespiratory fitness levels.