Relative importance of baseline and longitudinal evaluation in the follow-up of vasodilator therapy in pulmonary arterial hypertension

Objectives: The aim of this study was to evaluate the relative value of baseline and follow-up echocardiographic assessment of pulmonary artery systolic pressure (PASP) and right ventricular (RV) function in assessing response to vasodilator therapy in pulmonary arterial hypertension (PAH).

Background: Routine follow-up of PASP and RV function is widely obtained in patients undergoing treatment for PAH, but the value of this reassessment is uncertain.

Methods: Of 162 prospectively recruited patients with PAH, 96 were included in this analysis of patients with ≥3 sequential echocardiographic studies. PASP and RV function (including right ventricular free wall strain [RVFWS]) were measured at baseline and on follow-up 2-dimensional echocardiography. Univariate and multivariate Cox regression with nested models was used to determine incremental and independent predictors of all-cause mortality.

Results: Changes between visits were minimal for all parameters (RVFWS, p = 0.46; RV end diastolic area, p = 0.48; tricuspid annular plane systolic excursion, p = 0.32; PASP, p = 0.66; right atrial area, p = 0.39; and inferior vena cava, p = 0.25). Over 3 years of follow-up, 29 patients died. Baseline RVFWS was an independent predictor of outcome (hazard ratio [HR]: 0.90; 95% confidence interval [CI]: 0.83 to 0.97; p = 0.007), incremental to PASP and other clinical covariates (C statistic = 0.74, p = 0.001). Those who died showed no differences in RVFWS (p = 0.50), PASP (p = 0.90), and tricuspid annular plane systolic excursion (p = 0.83) between visits. When baseline measures and follow-up time were accounted for, mean changes in RVFWS (HR: 0.78; 95% CI: 0.63 to 0.96; p = 0.002), right atrial area (HR: 1.20; 95% CI: 1.07 to 1.40; p = 0.003), and inferior vena cava (HR: 66.5; 95% CI: 8.5 to 520.5; p < 0.001) over follow-up were significant in predicting outcome.

Conclusions: In PAH, baseline RV function (RVFWS) is a strong predictor of outcome, independent of PASP. Changes throughout therapy appear minimal, and only changes in RVFWS, inferior vena cava, size, and right atrial area were associated with outcome.