Oxygen uptake efficiency slope predicts poor outcome in patients with idiopathic pulmonary arterial hypertension

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. © 2017 the authors.