TY - JOUR T1 - Exercise oxygen uptake efficiency slope independently predicts poor outcome in pulmonary arterial hypertension JF - European Respiratory Journal JO - Eur Respir J SP - 1510 LP - 1512 DO - 10.1183/09031936.00167713 VL - 43 IS - 5 AU - Roberta P. Ramos AU - Jaquelina S. Ota-Arakaki AU - Maria Clara Alencar AU - Eloara V.M. Ferreira AU - Luiz Eduardo Nery AU - J. Alberto Neder Y1 - 2014/05/01 UR - http://erj.ersjournals.com/content/43/5/1510.abstract N2 - To the Editor:Pulmonary arterial hypertension (PAH) remains a disabling and frequently lethal disease despite remarkable advances in treatment. Cardiopulmonary exercise testing (CPET) has proved a valuable tool to objectively quantify disease severity and estimate prognosis in these patients [1–3].Exercise intolerance is characteristically multifactorial in PAH. Among its potential contributing mechanisms, increased ventilatory response, deranged pulmonary mechanics, peripheral muscle impairment and reduced oxygen delivery have been more widely investigated [1–5]. In this context, a CPET-derived variable that conflates the effects of increased ventilation and poor O2 transfer and/or peripheral O2 utilisation is the O2 uptake efficiency slope (OUES) [6]. OUES is the slope of the linear relationship between O2 uptake (V′O2) and the logarithmic transformation of minute ventilation (V′E) during rapidly incremental exercise, i.e. it aims to reflect how effectively O2 is extracted from the atmosphere and taken into the body as exercise progresses. We recently found that a combination of increased sub-maximal exercise V′E as a function of carbon dioxide output (V′CO2) and reduced O2 delivery/utilisation (as suggested by shallow V′O2–work rate relationship) were independent predictors of negative outcome in PAH of mixed aetiology [7]. These findings prompted the hypothesis that OUES would combine the prognostic information provided separately by those variables, thereby being the single predictor of poor outcome in our cohort.In order to address this question, we revisited our dataset and contrasted OUES prognostic relevance with that of a range of resting and cardiopulmonary exercise responses to ramp-incremental cycle ergometry. In the previous report [7], we described results from a group of 84 patients in whom 16 PAH-related deaths and two … ER -