The incremental prognostic importance of body fat adjusted peak oxygen consumption in chronic heart failure

OBJECTIVES We sought to assess whether the adjustment of peak oxygen consumption (PkVO(2)) to lean body mass would yield a more accurate discriminator of outcomes in the chronic heart failure population. BACKGROUND Peak oxygen consumption is traditionally used to risk stratify patients with congestive heart failure (CHF) and to time cardiac transplantation. There is, however, considerable variability in body fat content, which represents metabolically inactive mass. METHODS In 225 consecutive patients with CHF, the percentage of body fat was determined by the sum of skinfolds technique. All underwent CPX using a ramping treadmill protocol. Mean follow-up duration was 18.9 +/- 11.3 months. RESULTS There were 14 cardiovascular deaths and 15 transplants. Peak oxygen consumption lean, both as a continuous variable and using a cutoff of less than or equal to 19 ml/kg/min, was a better predictor of outcome than unadjusted PkVO(2) (p = 0.003 vs. 0.027 for the continuous variables and p = 0.0006 vs. 0.055 for less than or equal to 19 ml/kg/min and less than or equal to 14 ml/kg/min unadjusted body weight, respectively). Using partial correlation index R statistics, the Cox model using PkVO(2) lean less than or equal to 19 ml/kg/min, in addition to age and etiology of CHF as covariates, yielded the strongest predictive relationship to the combined end point (chi-square value 24.32). Especially in the obese patients and in women, there was considerably better correlation of PkVO(2) lean with outcome than the unadjusted PkVO(2). CONCLUSIONS The adjustment of PkVO(2) to lean body mass increases the prognostic value of cardiopulmonary stress testing in the evaluation of patients with chronic heart failure. The use of <19 ml O-2/kg of lean body mass/min as a cutoff in PkVO(2) should be used for timing transplantation, particularly in women and the obese. (C) 2000 by the American College of Cardiology.