Oxygen Uptake Efficiency Slope Predicts Major Cardiac Events in Patients With End-Stage Heart Failure

Abstract

IntroductionOxygen uptake efficiency slope (OUES) has been shown as a predictor of stable heart failure (HF) survival. However, there is a lack of evidence for end-stage HF. ObjectivesWe aimed to investigate the prognostic value of OUES in end-stage HF patients. MethodsThe study design was a retrospective cohort. End-staged HF patients who had cardiopulmonary exercise testing (CPET) for evaluation between 2004 and 2009 were included. The primary outcomes were cardiac death and heart transplantation. The independent survival predictors were determined using Cox regression hazard model adjusted for demographics, New York Heart Association (NYHA) classification, medication, and left ventricular ejection fraction (LVEF). The Kaplan-Meier survival curves and log-rank test were used. Probability values less than .05 were considered significant. ResultsMean age of the 128 patients was 50 ± 12 years and 93 were male. Mean LVEF was 23% ± 9%. Forty-three subjects suffered cardiac events (5 cardiac deaths and 38 urgent heart transplantations) during the 2-year follow-up period. Cox regression indicated that OUES and diuretics were significant predictors of 2-year survival, although peak oxygen uptake and ventilatory equivalent of carbon dioxide were not. Patients with high OUES (≥1.6) had a higher survival rate (P < .001; odds ratio [OR], 13.10; 95% confidence interval [CI], 3.30–58.63). The Kaplan-Meier curves show survival was significantly higher in those with OUES ≥1.6. ConclusionsOUES might be an aid in prognosis of patients with end-stage HF and useful in the assessment of patients unable to perform maximal exercise testing.