Discussion:
In our study comprising 500 consecutive patients with a broad spectrum of cardiovascular disorders, we evaluated the accuracy of commonly used echocardiographic parameters, including peak systolic annular velocity (s’), tricuspid annular plane systolic excursion (TAPSE), RV fractional area change (RV FAC), as well as RV strain, compared to CMR RV ejection fraction (RVEF) in assessing RV systolic function. To the best of our knowledge, this is the largest study that contains a variety of patient population and compares echocardiographic parameters with RVEF measured by CMR . This is also the first study to demonstrate the superior accuracy of RV free wall strain compared to other echocardiographic parameters to distinguish RVEF < 45% and RVEF <30%.
Similar to previous studies , we choose CMR measured RV ejection fraction (RVEF) as our reference standard for RV systolic function assessment. CMR enjoys the advantage of 3D volumetric information and high spatial resolution to analyze the distinctive geometry of RV, which is usually difficult to obtain by using 2D echocardiography measurements. The accuracy and reproducibility of using CMR for quantitative RV assessment have been demonstrated in multiple clinical studies. As a functional parameter, RVEF reflects the contractility of right heart myocardium, and can be affected by RV preload, afterload, and other general variables including age, sex and body mass index. Age and gender did not differ significantly between the groups in our study, but the percentage of men was higher in Group B.
Among the four echocardiographic parameters, our results indicate that RV strain and RV FAC are in general superior to TAPSE and S’ in accuracy, when compared with CMR RVEF by both spearman’s correlation and ROC curve analyses. Our results demonstrated a comparable or better reproducibility of each parameter, compared to prior studies. This finding suggests that two-dimensional parameters are superior two one-dimensional parameters and implies the importance of using two-dimensional or even three-dimensional tools for accurate RV function assessment concerning its complex geometry.