Right ventricular global wasted work in pulmonary arterial hypertension by 2D echocardiography predicts high mortality risk using a spline curve-derived cut-off

We appreciate the interest of Venkateshvaran et al.1 in our study, which underscored the association of right-ventricular (RV) global wasted work (GWW) with invasive haemodynamics and a high mortality risk profile in patients with pulmonary arterial hypertension (PAH).2 GWW is a novel concept of ventricular energetics that describes the inefficient energy expenditure caused by myocardial lengthening during systole and shortening during isovolumic relaxation. In the setting of PAH, elevated afterload may lead to maladaptive RV remodelling, characterized by post-systolic shortening, septal dyssynchrony, and functional tricuspid regurgitation. These pathophysiological alterations are reflected by increase in RVGWW, indicative of the energy loss to dyssynchronous or regurgitant RV contraction.3 The limited number of echocardiographic parameters recommended by the ESC/ERS guidelines4 for risk assessment in PAH, underscores the clinical value of our study to propose a spline-curve-derived RVGWW cut-off that identifies patients at high risk of death and predicts key haemodynamic invasive indices.2 In a comparable cohort of PAH, Venkateshvaran et al. reported that individuals with RVGWW ≥ 38 mmHg/% had worse survival.5 This threshold differs substantially from the RVGWW cut-off of 175 mmHg/% identified in our study as predictive of the guidelines suggested high-risk profile in PAH.