Prognostic significance of different measures of the ventilation-carbon dioxide relation in patients with suspected heart failure.
OBJECTIVE
We studied the prognostic significance of the ventilatory equivalent of carbon dioxide production (VEqCO(2)) at different time-points of a maximal cardiopulmonary exercise test (CPET) in patients with suspected heart failure (HF).


RESULTS
The VEqCO(2) was calculated at three different time-points; VEqCO(2) (rest) was calculated following 30 s of resting data immediately prior to the start of exercise; VEqCO(2) (nadir) was the lowest 30-s average over the duration of the test; VEqCO(2) (peak) was calculated using the mean value of the final 30 s of exercise. We included a healthy control group who had no evidence of cardiorespiratory disease. Four hundred and twenty-three patients with suspected HF (mean age 63 ± 12 years; 80% males; left ventricular ejection fraction 36 ± 6 %; peak oxygen uptake 22.3 ± 8.1 mL kg(-1) min(-1); VE/VCO(2) slope 34 ± 8) were included in the study. Seventy-eight healthy participants (62% males; age 61 ± 11 years) were recruited as controls. One hundred and eighteen patients died during follow-up with a median follow-up of 8.6 ± 2.1 years in survivors. The strongest univariable predictors of all-cause mortality were VEqCO(2) (nadir) (χ(2) = 47.9), peak oxygen uptake (χ(2) = 53.0), and the VE/VCO(2) slope (χ(2) = 31.7). In a Cox multivariable proportional hazards model, VEqCO(2) (nadir) (χ(2) = 8.8), peak systolic blood pressure (χ(2) = 6.0), and age (χ(2) = 6.6) were the most potent independent predictors of all-cause mortality.


CONCLUSIONS
The VEqCO(2) (nadir) provides greater prognostic value than other related ventilatory variables in patients with suspected HF. Further work in other populations is required to confirm our conclusions.
Carnegie Research Institute, Leeds Metropolitan University, Beckett's Park, Headingley, Leeds, UK. l.ingle@leedsmet.ac.uk
Lee
L
Ingle
Rebecca
R
Sloan
Sean
S
Carroll
Kevin
K
Goode
John G
JG
Cleland
Andrew L
AL
Clark
D000368:Aged; D002245:Carbon Dioxide / Q000378:metabolism*; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011379:Prognosis; D016016:Proportional Hazards Models; D012123:Pulmonary Ventilation / Q000502:physiology; D012372:ROC Curve
D002245:Carbon Dioxide