In their recently published article, Sato et al. investigated the accuracy of echocardiographic measures of right ventricular (RV) systolic function (mean RV ejection fraction [RVEF], 38 ± 11%) in 37 patients with a mean systolic pulmonary artery pressure of 64 ± 20 mm Hg using cardiac magnetic resonance imaging (CMRI)–derived RVEF. They showed that tricuspid annular plane systolic excursion (TAPSE) ( r = 0.86) and systolic lateral tricuspid annular motion velocity (TV lat ) ( r = 0.63) were strongly correlated with CMRI-derived RVEF. In multivariate regression analysis, TAPSE was an independent predictor of RVEF. The authors emphasized the importance of validation of echocardiographic parameters of RV systolic dysfunction in patients with pulmonary hypertension. However, they did not report any cutoff values for TAPSE and TV lat in the prediction of RV systolic dysfunction.
RV systolic dysfunction is accepted as a negative prognostic factor in pulmonary hypertension, coronary artery disease, and congestive heart failure. Ejection fraction < 44% established by three-dimensional echocardiography and CMRI and fractional area change < 35% by two-dimensional echocardiography are accepted as indicating RV systolic dysfunction. In the normal population, the accepted lower reference value for TAPSE is 16 mm (95% confidence interval, 15–18 mm), and that for TV lat is 10 cm/sec (95% confidence interval, 9–11 cm/sec). Wahl et al. reported that TV lat < 12 cm/sec indicates CMRI-derived RVEF < 50% with 81% sensitivity and 68% specificity and that TV lat < 9 cm/sec distinguishes severely reduced RVEF (<30%). Wang et al. reported that TV lat < 8.8 cm/sec discriminate RV systolic dysfunction (RVEF < 45%) in patients with arrhythmogenic RV dysplasia without pulmonary artery hypertension. Leong et al. reported cutoff values of <19 mm for TAPSE and <7.4 cm/sec for TV lat for the prediction of RVEF < 45% in patients with heart failure.
Assessment of RV function in patients with pulmonary hypertension may be problematic, because of the strong correlations among pulmonary artery systolic pressure, pulmonary vascular resistance, RV dilatation, TAPSE, and TV lat . Saxena et al. reported that TV lat < 10.5 cm/sec may identify patients with depressed RV function and elevated pulmonary artery pressures. In a previous report, we showed that TV lat < 11 cm/sec may predict pulmonary artery systolic pressure > 30 mm Hg with sensitivity of 57% and specificity of 93% in patients with congenital heart disease with normal left ventricular and RV systolic function.
In conclusion, RV systolic function may be challenging to evaluate by echocardiography using volumetric methods, so nonvolumetric measures of RV function, including TAPSE and TV lat , are used commonly in clinical practice. However, the accuracy of these parameters has not been validated extensively in pulmonary hypertension. In our opinion, data from the study by Sato et al. can add valuable information to the literature regarding the optimal cutoff values for TAPSE and TV lat in the prediction of RV dysfunction.