Right ventriculo-arterial coupling assessed by right ventricular strain is a superior predictor of clinical outcome in patients with pulmonary arterial hypertension

We thank Tello et al.1 for their interest in our work in which we described a novel echocardiographic parameter (right ventricular free wall strain/pulmonary artery pressure ratio) to predict clinical outcome in pre-capillary pulmonary arterial hypertension patients. Right ventricular (RV) function is closely associated with mortality in all pulmonary hypertension groups. RV function has the ability to increase its contractility by adaptive mechanisms in response to increased afterload from the pulmonary vascular system during the disease process. However, at some point, the RV can no longer adapt to the increased afterload and RV failure occurs. The interrelation between the pulmonary vascular system and RV is described as RV-pulmonary artery (PA) coupling and has been presented as the ratio of RV function to pulmonary vascular afterload. The gold standard for measuring RV-PA coupling is obtaining the ratio of RV end-systolic elastance (Ees) to pulmonary arterial elastance (Ea) invasively, where Ees/Ea ratio represents coupling. To overcome the invasive nature and complexity of the measurement, several non-invasive methods have been proposed to estimate RV-PA coupling. The tricuspid annular plane systolic excursion (TAPSE)/systolic pulmonary artery pressure (sPAP) ratio was mostly investigated echocardiographic surrogate for RV-PA coupling.2,3