Fluid challenge predicts clinical worsening in pulmonary arterial hypertension

A fluid challenge with rapid saline infusion during right heart catheterization has been shown to be useful for the differential diagnosis between pre- and post-capillary pulmonary hypertension. The aim of this study was to evaluate the prognostic relevance of fluid challenge-induced changes in pulmonary hemodynamics in patients with pulmonary arterial hypertension (PAH).

Overall, 118 PAH patients (mean age 57 ± 15 years, 80 female) underwent hemodynamic measurements before and after rapid saline infusion (7 mL/kg in 10 min) and were followed up for 19 ± 4 months.

Thirty-two patients (27%) had a clinical worsening event defined as the occurrence of one of the following: death, lung transplantation, initiation of parenteral prostanoids, or worsening of PAH (defined as the presence of all of the three following components: a decrease in the 6-minute walk distance of at least 15% from baseline, worsening of PAH symptoms, and need for new PAH treatment). Cardiac index (CI), stroke volume and pulmonary artery compliance were lower whereas right atrial pressure (RAP), the ratio of RAP to pulmonary artery wedge pressure (PAWP) and pulmonary vascular resistance were higher in patients with a clinical worsening event versus patients without events, both at baseline and after fluid challenge (all p < 0.01). At multivariable Cox proportional hazards regression analysis, a post-fluid challenge CI <2.8 L/min/m² (hazard ratio 0.0143; 95% confidence interval 0.006-0.3383; p = 0.009) was the only independent predictor of outcome.

CI measured after a fluid challenge is an independent predictor of outcome in PAH.