Baseline RV function is a stronger predictor of response to vasodilators in pulmonary hypertension than six-minute walk

Abstract

Background: The availability of sensitive markers of RV function might reduce the reliance on treatment response to select suitable pts for pulmonary vasodilator therapy. We hypothesised that baseline RV function would be more predictive of responders to Rx, than six-minute walk (6MW).We therefore compared change in pulmonary vascular resistance (PVR) with baseline echo or functional status (6MW). Methods: We assessed patients at baseline and follow up after treatment (mean follow up 0.75±0.52 years), and assessed whether patients had normalised PVR (PVR<2.5 w/u, n=19), or increased PVR at follow up (n=11). 6MWwas performed at time of echo. RV function was measured by RV free wall longitudinal strain (FWLS), and RV end-diastolic area (EDA). Baseline factors associated with haemodynamic improvement were sought with univariable and multivariable regression and ROC curves (graph1) were used to assess predictive ability. Results: FWLS and RVEDA showed univariable association with change in PVR but age, HR and 6MW were not associated. Binary logistic regression (R2=0.45, p=0.001) showed RV FWLS ( =1.42, [CI1.055-1.9], p=0.02), was associated with PVR independent of 6MW ( =1.00 [CI.99-1.01], p=0.69), HR, BMI & age. The prediction of normalisation of PVR with FWLS (AUC=0.75), TAPSE, (AUC=0 .83) RVEDA (AUC=0.82), exceeded that of 6MW (AUC=0.37). Conclusion: Baseline RV function is a better tool to predict responders to PAH therapy than 6MW.