title: Oscillatory breathing and exercise gas exchange abnormalities prognosticate early mortality and morbidity in heart failure.
abstract: OBJECTIVE
  The goal of this study was to identify better predictors of early death in patients with chronic left ventricular heart failure (CHF). Potential predictors, derived from cardiopulmonary exercise testing, were compared with other commonly used cardiovascular measurements.
  
  
  BACKGROUND
  The prediction of early death in patients with CHF remains challenging.
  
  
  METHODS
  Five hundred eight patients with CHF due to systolic dysfunction underwent resting cardiovascular measurements, 6-min walking tests, and cardiopulmonary exercise testing. The peak oxygen uptake (.VO(2)), peak oxygen pulse, anaerobic threshold, ratio of ventilation to carbon dioxide output (.VE/.VCO(2)), slope of .VE versus .VCO(2), and presence or absence of a distinctive oscillatory breathing pattern (OB) were ascertained. Outcomes were 6-month mortality and morbidity, the latter a sum of cardiac hospitalizations and deaths.
  
  
  RESULTS
  The single best predictor of mortality was an elevated lowest .VE/.VCO(2) (> or =155% predicted). Adding OB on the basis of stepwise regression (optimal 2-predictor model), the odds ratio for mortality increased from 9.4 to 38.9 (p < 0.001). The slope of .VE versus .VCO(2) slope, peak .VO(2), peak oxygen pulse, and anaerobic threshold combined with OB were also strong predictors. OB also increased the odds ratio 2- to 3-fold for each of these (p < 0.01). Kaplan-Meier survival curves and area under the receiver-operating characteristic curve confirmed that lowest .VE/.VCO(2) and OB were superior. For morbidity, elevated lowest .VE/.VCO(2) or lower peak .VO(2) with OB were the best predictors. No nonexercise measurements discriminated mortality and morbidity.
  
  
  CONCLUSIONS
  Cardiopulmonary exercise testing parameters are powerful prognosticators of early mortality and morbidity in patients with CHF, especially the optimal 2-predictor model of a combination of elevated lowest .VE/.VCO(2) and OB.
authors.affiliation: Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 West Carson Street, Torrance, CA 90502, USA. xgsun@labiomed.org
authors.forename: Xing-Guo
authors.initials: XG
authors.lastname: Sun
authors.forename: James E
authors.initials: JE
authors.lastname: Hansen
authors.forename: John F
authors.initials: JF
authors.lastname: Beshai
authors.forename: Karlman
authors.initials: K
authors.lastname: Wasserman
mesh_terms: D000368:Aged; D002908:Chronic Disease; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011659:Pulmonary Gas Exchange; D018754:Ventricular Dysfunction / Q000150:complications