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. 2017 Jun 30;6(7):e005037.
doi: 10.1161/JAHA.116.005037.

Oxygen Uptake Efficiency Slope Predicts Poor Outcome in Patients With Idiopathic Pulmonary Arterial Hypertension

Yi Tang  1 , Qin Luo  1 , Zhihong Liu  2 , Xiuping Ma  1 , Zhihui Zhao  1 , Zhiwei Huang  1 , Liu Gao  1 , Qi Jin  1 , Changming Xiong  1 , Xinhai Ni  1
Affiliations

Oxygen Uptake Efficiency Slope Predicts Poor Outcome in Patients With Idiopathic Pulmonary Arterial Hypertension

Yi Tang et al. J Am Heart Assoc. .

Abstract

Background: Few published studies have evaluated the power of the oxygen uptake efficiency slope (OUES) to predict outcomes in patients with idiopathic pulmonary arterial hypertension (IPAH), who typically die of right-sided heart failure. Our study sought to evaluate the power of OUES to predict clinical worsening and mortality in patients with IPAH.

Methods and results: Patients with newly diagnosed IPAH who underwent symptom-limited cardiopulmonary exercise testing from November 11, 2010, to June 25, 2015, in our hospital were prospectively enrolled and followed for up to 66 months. Clinical worsening and mortality were recorded. A total of 210 patients with IPAH (159 women; mean age, 32±10 years) were studied with a median follow-up of 41 months. Thirty-one patients died, 1 patient underwent lung transplantation, and 85 patients presented with clinical worsening. The univariate analysis revealed that OUES, OUESI (OUESI=OUES/body surface area), peak oxygen uptake (V˙O2), peak V˙O2/kg, ventilation (V˙E)/carbon dioxide output (V˙CO2) slope, peak systolic blood pressure, heart rate recovery, pulmonary vascular resistance, cardiac index, N-terminal prohormone brain natriuretic peptide, and World Health Organization functional class were all predictive of clinical worsening and mortality (all P<0.05). Multivariate analysis demonstrated that OUESI and cardiac index were independently predictive of clinical worsening, and OUESI and N-terminal prohormone brain natriuretic peptide were independently predictive of mortality. Patients with OUESI ≤0.52 m-2 had a worse 5-year survival rate than patients with OUESI >0.52 m-2 (41.9% versus 89.8%, P<0.0001).

Conclusions: The OUES, a submaximal parameter obtained from cardiopulmonary exercise testing, provides prognostic information for predicting clinical worsening and mortality in patients with IPAH.

Keywords: cardiopulmonary exercise testing; idiopathic pulmonary arterial hypertension; oxygen uptake efficiency slope.

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Figures

Figure 1
Figure 1
The relationship between V˙O2 and V˙E during incremental exercise in a 58‐year‐old woman with idiopathic pulmonary arterial hypertension. Linear (A) and semi‐log (x axis) plots of the data (B) are presented.
Figure 2
Figure 2
Mean values of oxygen uptake efficiency slope (OUES) divided into World Health Organization (WHO) functional classes.
Figure 3
Figure 3
Mean values of oxygen uptake efficiency slope index (OUESI) divided into World Health Organization (WHO) functional classes.
Figure 4
Figure 4
Kaplan–Meier analysis of oxygen uptake efficiency slope index (OUESI) for 5‐year mortality. Adjusted HR indicates hazard ratio (HR) adjusted for age, sex, and body mass index.
Figure 5
Figure 5
Kaplan–Meier analysis of oxygen uptake efficiency slope index (OUESI) for 5‐year clinical worsening. Adjusted HR indicates hazard ratio (HR) adjusted for age, sex, and body mass index.
See this image and copyright information in PMC

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