INTRODUCTION
Right ventricular (RV) dysfunction was established to be an important outcome predictor in both arterial pulmonary hypertension (PH) [1] and left heart disease [2]. Beyond RV systolic performance, the mechanical efficiency of the ventriculo-vascular interplay also has prognostic implications [3-4]. The right ventricular-pulmonary artery coupling (RVPAC) reflects the interaction between the right heart and the pulmonary circulation unit, which is optimal when all the mechanical energy of the RV is transferred to the vascular bed [5], providing an adequate cardiac output with minimal energy consumption [6].
RVPAC is defined as the ratio between end-systolic RV elastance (EES) and pulmonary arterial elastance (Ea), which is calculated using pressure-volume loops derived from right heart catheterization (RHC). Due to its technical complexity, the assessment of RVPAC is not routinely performed. However, non-invasive estimation of RVPAC can be done using cardiac magnetic resonance (CMR) [7] or transthoracic echocardiography [8], and non-invasive parameters showed good correlation with catheterisation-derived measurements [7-10]. Three-dimensional (3D) echocardiography overcomes the pitfalls of conventional RV functional assessment [11] and has been validated against CMR [12]. A 3D echocardiographic estimation of RVPAC has been proposed, as the ratio between RV stroke volume (SV) and RV end-systolic volume (ESV), which was found to have good correlation with catheterisation-derived RVPAC [13].
We hypothesized that right ventriculo-vascular decoupling plays a role in the occurrence of heart failure (HF) symptoms in patients with dilated cardiomyopathy (DCM). Consequently, our aim was to evaluate the RVPAC using 3D echocardiography in patients with DCM and to assess its relationship with the severity of HF symptoms in this setting.