Age-Related Differences in Hemodynamics and Functional Status in Pulmonary Arterial Hypertension: Baseline Results from the Pulmonary Hypertension Association Registry

ABSTRACT Background The age of patients with pulmonary arterial hypertension (PAH) has increased, with registries now reporting mean ages of 50-65 years old. Limited data exist on age-related differences in hemodynamic and functional assessments in PAH. Methods Adults with PAH in the Pulmonary Hypertension Association Registry were divided into three groups (18-50, 51-65, >65 years old). ANOVA and chi-squared testing were used to assess for baseline differences. Linear regression was used to examine the association of age with continuous hemodynamic and functional variables. Results 769 patients with mean age of 56±16 years were included. Older patients had more connective tissue disease-associated PAH and less drug-associated PAH. In linear regression models, each year of increased age was associated with shorter six-minute walk distance (6MWD) (-3.37meters, 95%CI -3.97 to -2.76), lower mean pulmonary arterial pressure (-0.21mmHg; 95%CI -0.27 to -0.15), and lower pulmonary vascular resistance (PVR) (-0.06 Wood units; 95%CI -0.09 to -0.04). Pulmonary arterial compliance, cardiac index, right ventricular stroke work index, and percent predicted 6MWD were unrelated with age; resistance-compliance time was negatively related to age (-3 milliseconds per year; 95%CI -4 to -2). Conclusions Relative to their PVR, older patients have lower pulmonary artery compliance and worse right ventricular performance. Based on these findings, we suspect that age influences right ventricular loading conditions and the response of the right ventricle to increased afterload.