title: The ventilatory classification system effectively predicts hospitalization in patients with heart failure.
abstract: BACKGROUND
  The minute ventilation carbon dioxide production (VE/VCO2) slope is a consistent and robust prognostic marker in the heart failure (HF) population. The purpose of this study was to assess the ability of the newly developed ventilatory classification system, a powerful predictor of major cardiac events (mortality, transplantation, and left ventricular assist device implantation), to identify varying degrees of risk for cardiac-related hospitalization.
  
  
  METHODS
  A total of 459 patients with chronic HF who underwent cardiopulmonary exercise testing were included in this analysis. The VE/VCO2 slope was determined, and participants were classified into 1 of 4 groups (ventilatory class [VC]-I: < or =29.9; VC-II: 30.0-35.9; VC-III: 36.0-44.9; and VC-IV: > or =45.0). Participants were tracked for cardiac-related hospitalization for 2 years following testing.
  
  
  RESULTS
  There were 169 cardiac-related hospitalizations during the 2-year tracking period (annual event rate = 21.6%). Decompensated HF, cardiac ischemia, and cardiac arrhythmia were the reasons for hospitalization in 83%, 11%, and 6% of the cases, respectively. Kaplan-Meier analysis revealed that the VC system was prognostically significant (log-rank = 85.2, P < .001) and superior to the Weber classification system (log-rank = 70.0, P < .001).
  
  
  CONCLUSIONS
  This study indicates that the VC system, based on the VE/VCO2 slope, effectively identifies patients with HF at varying degrees of risk for cardiac-related hospitalization. Furthermore, this newly developed system prognostically outperformed the established Weber classification system based on peak oxygen uptake.
authors.affiliation: Department of Physical Therapy, Physiology, and Internal Medicine, Virginia Commonwealth University, Health Sciences Campus, Richmond, VA 23298, USA. raarena@vcu.edu
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.forename: Joshua
authors.initials: J
authors.lastname: Abella
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Peberdy
authors.forename: Daniel
authors.initials: D
authors.lastname: Bensimhon
authors.forename: Paul
authors.initials: P
authors.lastname: Chase
authors.forename: Marco
authors.initials: M
authors.lastname: Guazzi
mesh_terms: D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D006305:Health Status Indicators; D006333:Heart Failure / Q000145:classification* / Q000503:physiopathology* / Q000628:therapy; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010101:Oxygen Consumption; D011379:Prognosis; D012123:Pulmonary Ventilation; D012307:Risk Factors; D016896:Treatment Outcome