Ricerc@Sapienza

BACKGROUND: The added value of cardiopulmonary exercise testing (CPET) in the follow-up of patients with stable pulmonary arterial hypertension (PAH) remains undefined. METHODS: Idiopathic, heritable, and drug-induced PAH patients free from clinical worsening (CW) after 1 year of treatment were enrolled in derivation (n?=?80) and validation (n?=?80) cohorts at an interval of 6 years and followed for 3 years. Prognostic models were constructed and validated in low-risk patients in World Health Organization (WHO) Functional Class I or II with cardiac index (CI) ?2.5 liters/min/m2 and right atrial pressure (RAP) <8 mm Hg. Discrimination and calibration were assessed. RESULTS: Forty-one derivation cohort patients had CW (51.2%) during 722 ± 349 days. Changes (?) in WHO classification and CI and absolute value of RAP were independent predictors of CW. With addition of CPET variables, peak oxygen uptake (VO2 peak) and ?CI independently improved the power of the prognostic model. Receiver operating characteristic (ROC)-derived cut-off values for ?CI and VO2 peak were 0.40 liter/min/m2 and 15.7 ml/kg/min (?60% predicted value), respectively. Twenty-nine validation cohort patients had CW (36.2%) during 710 ± 282 days. Different combinations of cut-off values of VO2 peak and ?CI defined 4 groups. The event-free survival rates at 1, 2, and 3 years were 100%, 100%, and 100%, respectively, for the high ?CI with high VO2 peak combination; 100%, 88%, and 71% for low ?CI/high VO2 peak; 80%, 54%, and 40% for high ?CI/low VO2 peak; and 72%, 54%, and 33% for low ?CI/low VO2 peak. CONCLUSIONS: The combinations of baseline VO2 peak and change in CI during follow-up is important in prognostication of low-risk patients with idiopathic, heritable, and drug-induced PAH.