The value of hemodynamic measurements or cardiac magnetic resonance imaging in the follow-up of patients with idiopathic pulmonary arterial hypertension.

BACKGROUND Management of Pulmonary Arterial Hypertension (PAH) patients is conventionally based on functional plus invasive measurements obtained during right heart catheterization (RHC). Whether risk-assessment during repeated measurements could also be performed using imaging parameters is unclear, as a direct comparison of strategies is lacking. RESEARCH QUESTION How do the predictive value of non-invasive parameters compare with invasive hemodynamic measurements at 1 year after the diagnosis of iPAH? STUDY DESIGN & METHODS 118 iPAH-patients who underwent RHC and cardiac magnetic resonance imaging (CMR) were included in this study (median time between baseline evaluation and first parameter measures: 1.0[0.8-1.2] years). 44 patients died or received a lung transplantation. Forward cox-regression analyses were used to determine the best predictive functional, hemodynamic and/or imaging model. Patients were classified as high-risk if the event occurred <5 years after diagnosis (n=24), whereas patients without event were classified as low-risk. RESULTS A prognostic model that was based on age, sex and absolute values at follow-up of functional parameters (6-minute walk distance) performed well (Akaike information criterion (AIC): 279, concordance: 0.67). Predictive models with only hemodynamic (right atrial pressure, mixed venous oxygen saturation; AIC: 322, concordance: 0.68) or imaging parameters (right ventricular ejection fraction; AIC: 331, concordance: 0.63) at 1 year of follow up performed similar. The predictive value improved when functional data was combined with either hemodynamic data (AIC: 268, concordance: 0.69) or imaging data (AIC: 273, concordance 0.70). A model comprised of functional, hemodynamic and imaging data performed only marginally better (AIC: 266, concordance: 0.69). Finally, changes between baseline and 1 year follow up were observed for multiple hemodynamic and CMR-parameters, only a change in CMR-parameters was of prognostic predictive value. INTERPRETATION Risk-assessment at 1-year of follow-up based on CMR is at least equal to risk-assessment based on RHC. In this study, only changes in CMR- but not hemodynamic parameters are of prognostic predictive value during the first-year of follow-up.