Right Ventricular Dyssynchrony in Idiopathic Pulmonary Arterial Hypertension: Insights From Echocardiographic and Cardiac Magnetic Resonance Imaging

Right ventricular dyssynchrony (RVD) has been described in pulmonary arterial hypertension (PAH), but no evidence is available on its morphological determinants and its effect on systolic function. The aim of this study was to evaluate the morphological determinants of RVD by echocardiographic and cardiac magnetic resonance imaging and its effect on systolic function. In 60 consecutive idiopathic PAH (IPAH) patients RVD was evaluated by 2D speckle-tracking echocardiography calculating the standard deviation of the times to peak-systolic strain for the 4 mid-basal right ventricular segments (RV-SD4). Patients were grouped by the median value of RV-SD4 (19 ms) and compared for RV remodeling and systolic function parameters, WHO class, pulmonary hemodynamics and 6-minute walk test (6MWT). Despite similar pulmonary vascular resistance and mean pulmonary arterial pressure, patients with RV-SD4 >19 ms had advanced WHO class, worse 6MWT, RV hemodynamics, RV remodeling and systolic function parameters compared to patients ≤19 ms. The morphological determinants of RVD resulted RV end-diastolic area, left ventricular diastolic eccentricity index and RV mass-volume ratio (r= 0.69; r2= 0.47; p<0.0001). The strongest inverse correlation was found between RV mid-basal segments postsystolic shortening (PSS) time and cardiac index (CI) (r=-0.64, r2=0.41, p=0.001), accounting for the significant correlation between RV-SD4 and CI (r=0.57, r2=0.32, p=0.003). A weaker correlation was found between CI and RV fractional area change (r=0.33, p=0.009), RV ejection fraction (r=0.35, p=0.006), pulsed-tissue Doppler systolic velocity (r=0.26, p=0.04) and RV 2D-strain (r=0.37, p=0.004). In IPAH RVD is associated to a more advanced RV remodeling and contributes to pump dysfunction through PSS.