Echocardiographic Assessment of Right Ventricular Function and Response to Therapy in Pulmonary Arterial Hypertension

ABSTRACT Echocardiography is a key tool in the management of patients with pulmonary arterial hypertension (PAH), but many potential parameters could be used to assess response to therapy. In this retrospective study of 48 patients with severe PAH at baseline, we examined echocardiographic variables before and after initiation of PAH-specific therapy to evaluate which measures of right ventricular (RV) function best correlated with clinical response to therapy as assessed by 6-minute walk distance (6MWD) and 3-year all-cause mortality. Tricuspid annular plane systolic excursion (TAPSE), mid-RV and basal-RV diameters, RV systolic pressure (RVSP), and RV global longitudinal strain (GLS) were all found to significantly improve after initiation of a PAH therapy. Decreases in RA area (r = -0.50, p = 0.002) and mid-RV diameter (r = -0.36, p = 0.03) were most strongly correlated with improvement in 6MWD. Pre-treatment values of RA area (HR per 1 SD: 2.72; 95% CI 1.58, 4.69), mid-RV diameter (HR 2.03; 1.20, 3.45), basal-RV diameter (HR 2.27; 1.40, 3.70) and RV GLS (HR 2.36; 1.22, 4.56) were all associated with mortality risk. 6MWD and TAPSE were the two variables for which pre-treatment measures (6MWD – HR 0.35; 0.17, 0.72; TAPSE – HR 0.41; 0.21, 0.82) and change with treatment (6MWD – HR 0.26; 0.10, 0.64; TAPSE – HR 0.40; 0.21, 0.77) were both significantly associated with 3-year mortality. Change in RVSP with treatment was significantly associated with mortality (HR 2.55; 1.23, 5.28,) but pre-treatment baseline had no association (HR 1.48; 0.72, 3.06). While many echocardiographic parameters change with initiation of PAH treatment, the strong association of both baseline TAPSE and change in TAPSE with mortality supports the ongoing use of TAPSE as an important measure in the assessment of disease severity and treatment response in PAH.