title: Impact of cardiorespiratory fitness on the obesity paradox in patients with heart failure.
abstract: OBJECTIVE
  To determine the impact of cardiorespiratory fitness (FIT) on survival in relation to the obesity paradox in patients with systolic heart failure (HF).
  
  
  METHODS
  We studied 2066 patients with systolic HF (body mass index [BMI] ≥18.5 kg/m(2)) between April 1, 1993 and May 11, 2011 (with 1784 [86%] tested after January 31, 2000) from a multicenter cardiopulmonary exercise testing database who were followed for up to 5 years (mean ± SD, 25.0±17.5 months) to determine the impact of FIT (peak oxygen consumption <14 vs ≥14 mL O2 ∙ kg(-1) ∙ min(-1)) on the obesity paradox.
  
  
  RESULTS
  There were 212 deaths during follow-up (annual mortality, 4.5%). In patients with low FIT, annual mortality was 8.2% compared with 2.8% in those with high FIT (P<.001). After adjusting for age and sex, BMI was a significant predictor of survival in the low FIT subgroup when expressed as a continuous (P=.03) and dichotomous (<25.0 vs ≥25.0 kg/m(2)) (P=.01) variable. Continuous and dichotomous BMI expressions were not significant predictors of survival in the overall and high FIT groups after adjusting for age and sex. In patients with low FIT, progressively worse survival was noted with BMI of 30.0 or greater, 25.0 to 29.9, and 18.5 to 24.9 (log-rank, 11.7; P=.003), whereas there was no obesity paradox noted in those with high FIT (log-rank, 1.72; P=.42).
  
  
  CONCLUSIONS
  These results indicate that FIT modifies the relationship between BMI and survival. Thus, assessing the obesity paradox in systolic HF may be misleading unless FIT is considered.
authors.affiliation: Department of Cardiovascular Diseases, John Ochsner Heart and Vascular Institute, Ochsner Clinical School-The University of Queensland School of Medicine, New Orleans, LA, USA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Lavie
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: Cahalin
authors.forename: Paul
authors.initials: P
authors.lastname: Chase
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.forename: Daniel
authors.initials: D
authors.lastname: Bensimhon
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Peberdy
authors.forename: Euan
authors.initials: E
authors.lastname: Ashley
authors.forename: Erin
authors.initials: E
authors.lastname: West
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Forman
authors.forename: Marco
authors.initials: M
authors.lastname: Guazzi
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016208:Databases, Factual; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D054143:Heart Failure, Systolic / Q000150:complications / Q000401:mortality* / Q000503:physiopathology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D010101:Oxygen Consumption; D010809:Physical Fitness; D016016:Proportional Hazards Models