Obesity and hemoglobin content impact peak oxygen uptake in human heart failure

Abstract

Background: Exercise intolerance, obesity, and low hemoglobin (hemoglobin<13 and <12 g/dl, men/women, respectively) are common features of heart failure. Despite serving as potent contributors to metabolic dysfunction, the impact of obesity and low hemoglobin on exercise intolerance is unknown. This study tested the hypotheses, compared with non-obese (NO) heart failure with normal hemoglobin, (a) counterparts with low hemoglobin and obesity or nonobesity will demonstrate reduced peak exercise oxygen uptake; (b) obese with normal hemoglobin will demonstrate decreased peak exercise oxygen uptake; (c) compared across stratifications, obese with low hemoglobin will demonstrate the sharpest decrement in peak exercise oxygen uptake. Methods: Adults with heart failure (n ¼ 315; left ventricular ejection fraction 40%; 77% men) (Group 1: normal hemoglobin and non-obese, n ¼ 137; Group 2: low hemoglobin and non-obese, n ¼ 51; Group 3: normal hemoglobinþobesity, n ¼ 89; Group 4, n ¼ 38: low hemoglobinþobesity; body mass index ¼ 26 AE 3, 26 AE 2, 34 AE 4, 34 AE 4 kg/m 2 , respectively) completed treadmill cardiopulmonary exercise testing as part of routine clinical management. Peak exercise oxygen uptake was measured via standard metabolic system. Results: There were no group-wise differences for heart failure class, gender, left ventricular ejection fraction, and resting cardiopulmonary function. Group 1 demonstrated increased peak exercise oxygen uptake versus Groups 2-4 (20 AE 6 versus 17 AE 6, 17 AE 5, 13 AE 4 ml/kg/min, respectively; all p < 0.001); whereas Group 4 peak exercise oxygen uptake was reduced versus all groups (p < 0.001). Additionally, both body mass index (R 2 ¼ 0.10) and hemoglobin (R 2 ¼ 0.12) were significant predictors of peak exercise oxygen uptake in Group 1; which were relationships not mirrored for Groups 2-4. Conclusion: These data suggest obesity together with low hemoglobin are potent contributors to impaired peak exercise oxygen uptake and, hence, oxidative metabolic capacity. In diverse populations of heart failure where obesity and/or low hemoglobin are present, it is important to consider these features together when interpreting peak exercise oxygen uptake and underlying exercise limitations.

Risk stratification in cardiomyopathy

“…4,5 At the same time, CPET variables are influenced by several factors: among others, recent data suggest for example that obesity may negatively affect peak oxygen consumption (VO 2 ). 6 Therefore, the assumption that their prognostic ability is reproducible to all patients with HF of its aetiology can be misleading in clinical practice. Consequently, CPET data need to be contextualised into specific groups of cardiomyopathies.…”

Editors’ presentation: Focus on cardiomyopathy and heart failure

“…Exercise intolerance and fatigue in HF: the role for group III/IV afferent feedback Exercise intolerance is a hallmark of chronic HF and is associated with reduced quality of life (QoL) and increased mortality. 15 The pathophysiological mechanisms behind exercise intolerance are multifactorial and only partially investigated and understood.…”

Obesity and heart failure with preserved ejection fraction

“…The authors also observed the implication of haemoglobin content as accounting for a significant proportion of the variability in cardiopulmonary exercise testing responses for patients above or below the generalised obesity threshold. 11 BMI and waist circumference could be reduced effectively by dietary approaches to stop hypertension and supervised aerobic exercise 2 days per week. The exercise should be high volume and high intensity interval training, which offers an optimal non-pharmacological tool in the maintenance of BMI and waist circumference below a threshold of obesity patients with HFpEF.…”