Study limitations
Our study had several limitations. First, it was a single-centre study, with a relatively small sample size. Further studies are needed to evaluate if our results apply to larger populations of DCM patients. Second, there are limitations inherent to 3D echocardiographic assessment, which is unreliable when a good acoustic window is lacking. The reproducibility of 3D RVPAC was good in our study, but we did have a risk of selection bias, since we excluded patients with poor acoustic window. Third, using the volume method for estimating RVPAC as the SV/ESV ratio will lead to underestimation of RVPAC. Nevertheless, the predictive value of the SV/ESV ratio in PH has been previously shown; in our study, this ratio was the only independent correlate of severely symptomatic status in a disease primarily involving the left heart.