Oxygen uptake efficiency plateau best predicts early death in heart failure.
BACKGROUND
The responses of oxygen uptake efficiency (ie, oxygen uptake/ventilation = VO(2)/VE) and its highest plateau (OUEP) during incremental cardiopulmonary exercise testing (CPET) in patients with chronic left heart failure (HF) have not been previously reported. We planned to test the hypothesis that OUEP during CPET is the best single predictor of early death in HF.


METHODS
We evaluated OUEP, slope of VO(2) to log(VE) (oxygen uptake efficiency slope), oscillatory breathing, and all usual resting and CPET measurements in 508 patients with low-ejection-fraction (< 35%) HF. Each had further evaluations at other sites, including cardiac catheterization. Outcomes were 6-month all-reason mortality and morbidity (death or > 24 h cardiac hospitalization). Statistical analyses included area under curve of receiver operating characteristics, ORs, univariate and multivariate Cox regression, and Kaplan-Meier plots.


RESULTS
OUEP, which requires only moderate exercise, was often reduced in patients with HF. A low % predicted OUEP was the single best predictor of mortality (P < .0001), with an OR of 13.0 (P < .001). When combined with oscillatory breathing, the OR increased to 56.3, superior to all other resting or exercise parameters or combinations of parameters. Other statistical analyses and morbidity analysis confirmed those findings.


CONCLUSIONS
OUEP is often reduced in patients with HF. Low % predicted OUEP (< 65% predicted) is the single best predictor of early death, better than any other CPET or other cardiovascular measurement. Paired with oscillatory breathing, it is even more powerful.
Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, St. John's Cardiovascular Research Center, Torrance, CA. Electronic address: xgsun@labiomed.org.
Xing-Guo
XG
Sun
Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, St. John's Cardiovascular Research Center, Torrance, CA.
James E
JE
Hansen
Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, St. John's Cardiovascular Research Center, Torrance, CA.
William W
WW
Stringer
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002303:Cardiac Output, Low / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D002423:Cause of Death; D017147:Defibrillators, Implantable; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000401:mortality* / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011237:Predictive Value of Tests; D011379:Prognosis; D011659:Pulmonary Gas Exchange; D016019:Survival Analysis; D055815:Young Adult