The prognostic value of cardiopulmonary exercise testing with a peak respiratory exchange ratio of <1.0 in patients with chronic heart failure.
BACKGROUND
Peak oxygen consumption derived from a maximal cardiopulmonary exercise test (CPET) is a standard prognostic indicator in patients with chronic heart failure (CHF). Tests with a peak respiratory exchange ratio (pRER)<1.0 are often taken to be submaximal, and data from such tests are treated as less helpful. The aim of the current study was to compare the prognostic value of CPETs with a peak respiratory exchange ratio (pRER)<1.0 versus a pRER>/=1.0 in a large, representative sample of patients with CHF.


RESULTS
445 patients underwent a symptom-limited, treadmill-based CPET using the modified Bruce protocol, [82% males; age 72 (65-79) years]. 255 patients completed the CPET with a pRER>/=1.0. 121 patients died, and in survivors, the median follow-up period was 42 months. 42% of patients could not perform a CPET with pRER>/=1.0 using a modified Bruce protocol. Independent predictors of mortality were peak oxygen uptake, and the VE/VCO(2) ratio. 190 patients completed the CPET with a pRER<1.0. Independent predictors of mortality were age, peak oxygen pulse, and history of angina. RER group (pRER<1.0 versus pRER>/=1.0) remained an independent predictor of mortality in all patients.


CONCLUSIONS
Independent predictors of mortality were different in patients with a pRER<1.0 compared to those with a pRER>/=1.0. In CHF patients with a pRER<1.0, traditional prognostic markers (VE/VCO(2) slope, peak oxygen uptake) were not independently predictive of mortality.
Ingle
Lee
L
Carnegie Research Institute, Leeds Metropolitan University, Beckett's Park, Headingley, Leeds, LS6 3QS, United Kingdom.
Witte
Klaus K
KK
Cleland
John G J F
JG
Clark
Andrew L
AL
D000368:Aged; D002908:Chronic Disease; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000401:mortality / Q000503:physiopathology*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D011379:Prognosis; D016016:Proportional Hazards Models; D011659:Pulmonary Gas Exchange; D018709:Statistics, Nonparametric