Cardiorespiratory Fitness as a Prognostic Factor in Heart Failure Needs to be Standardized for Body Composition




We read the recently published study by Clark et al of obesity as a positive prognostic factor in patients with advanced systolic heart failure (obesity paradox). The investigators observed the obesity paradox only in patients with lower cardiorespiratory fitness. Cardiorespiratory fitness was assessed as peak oxygen uptake (PKVO 2 ) divided by total body weight (ml/min/kg). This measure has been shown to systematically underestimate cardiorespiratory fitness in not only healthy populations but also subjects with heart failure. The bias can be avoided by expressing PKVO 2 as a function of lean mass.


The bias introduced by ignoring body composition in the assessment of cardiorespiratory fitness may be substantial. In the absence of direct measurements of lean mass, simple estimates based on weight, height, age, and gender are a fair substitute. We would therefore invite the investigators to use anthropometrics-based estimates of lean mass to standardize PKVO 2 for body composition. Results based on such a body composition–neutral measure would enable the investigators to assess the independent impact of cardiorespiratory fitness and may even help to resolve the obesity paradox.


References



  1. 1. Clark A.L., Fonarow G.C., and Horwich T.B.: Impact of cardiorespiratory fitness on the obesity paradox in patients with systolic heart failure. Am J Cardiol 2015; 115: pp. 209-213

  2. 2. Savonen K., Krachler B., Hassinen M., Komulainen P., Kiviniemi V., Lakka T.A., and Rauramaa R.: The current standard measure of cardiorespiratory fitness introduces confounding by body mass: the DR’s EXTRA study. Int J Obes (Lond) 2012; 36: pp. 1135-1140

  3. 3. Batterham A.M., Vanderburgh P.M., Mahar M.T., and Jackson A.S.: Modeling the influence of body size on V(O2) peak: effects of model choice and body composition. J Appl Physiol 1999; 87: pp. 1317-1325

  4. 4. Osman A.F., Mehra M.R., Lavie C.J., Nunez E., and Milani R.V.: The incremental prognostic importance of body fat adjusted peak oxygen consumption in chronic heart failure. J Am Coll Cardiol 2000; 36: pp. 2126-2131

  5. 5. Krachler B., Savonen K., Komulainen P., Hassinen M., Lakka T.A., and Rauramaa R.: Cardiopulmonary fitness is a function of lean mass, not total body weight: the DR’s EXTRA study. Euro J Prev Cardiol 2014; undefined:

  6. 6. Krachler B., Volgyi E., Savonen K., Tylavsky F.A., Alen M., and Cheng S.: BMI and an anthropometry-based estimate of fat mass percentage are both valid discriminators of cardiometabolic risk: a comparison with DXA and bioimpedance. J Obes 2013; 2013: pp. 862514

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Nov 28, 2016 | Posted by in CARDIOLOGY | Comments Off on Cardiorespiratory Fitness as a Prognostic Factor in Heart Failure Needs to be Standardized for Body Composition

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