Exercise oscillatory breathing and increased ventilation to carbon dioxide production slope in heart failure: an unfavorable combination with high prognostic value.
BACKGROUND
Increased slope of exercise ventilation to carbon dioxide production (VE/VCO2) is an established prognosticator in patients with heart failure. Recently, the occurrence of exercise oscillatory breathing (EOB) has emerged as an additional strong indicator of survival.


OBJECTIVE
The aim of this study is to define the respective prognostic significance of these variables and whether excess risk may be identified when either respiratory disorder is present.


METHODS
In 288 stable chronic HF patients (average left ventricular ejection fraction, 33 +/- 13%) who underwent cardiopulmonary exercise testing, the prognostic relevance of VE/VCO2 slope, EOB, and peak VO2 was evaluated by multivariate Cox regression.


RESULTS
During a mean interval of 28 +/- 13 months, 62 patients died of cardiac reasons. Thirty-five percent presented with EOB. Among patients exhibiting EOB, 54% had an elevated VE/VCO2 slope. The optimal threshold value for the VE/VCO2 slope identified by receiver operating characteristic analysis was < 36.2 or > or = 36.2 (sensitivity, 77%; specificity, 64%; P < .001). Univariate predictors of death included low left ventricular ejection fraction, low peak VO2, high VE/VCO2 slope, and EOB presence. Multivariate analysis selected EOB as the strongest predictor (chi2, 46.5; P < .001). The VE/VCO2 slope (threshold, < 36.2 or > or = 36.2) was the only other exercise test variable retained in the regression (residual chi2, 5.9; P = .02). The hazard ratio for subjects with EOB and a VE/VCO2 slope > or = 36.2 was 11.4 (95% confidence interval, 4.9-26.5; P < .001).


CONCLUSIONS
These findings identify EOB as a strong survival predictor even more powerful than VE/VCO2 slope. Exercise oscillatory breathing presence does not necessarily imply an elevated VE/VCO2 slope, but combination of either both yields to a burden of risk remarkably high.
Guazzi
Marco
M
Cardiopulmonary Unit, University of Milano, Milano, Italy. marco.guazzi@unimi.it
Arena
Ross
R
Ascione
Aniello
A
Piepoli
Massimo
M
Guazzi
Maurizio D
MD
D002245:Carbon Dioxide / Q000378:metabolism*; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis* / Q000378:metabolism / Q000401:mortality / Q000503:physiopathology*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012123:Pulmonary Ventilation; D012372:ROC Curve; D012119:Respiration; D016019:Survival Analysis; D014768:Virginia / Q000453:epidemiology
D002245:Carbon Dioxide