Author + information
- Michael Dandel, MD, PhD∗ ( and )
- Roland Hetzer, MD, PhD
- ↵∗Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
We read with interest the study by Wright et al. (1). Investigating the clinical value of echocardiographic assessment of right ventricular (RV) function for the evaluation of pulmonary arterial hypertension (PAH) therapy results, they found that follow-up echocardiography focusing on the right ventricle improves surveillance of patients with PAH.
We completely agree with that statement, even though some findings may appear less convincing. Thus, whereas both RV free wall strain (RVFWS) and tricuspid annular plane systolic excursion (TAPSE) were baseline predictors of outcomes, their changes over time were predictive only for RVFWS changes throughout therapy (1). In any case, this does not preclude the possibility that RV contractile performance can predict the course of PAH, as long as the impact of tricuspid regurgitation (TR) is neglected. TR accompanying RV dilation can induce misleading overestimation of RV contractile function by facilitating RV systolic wall motion and RV myocardial deformation, which will increase TAPSE and RVFWS correspondingly to the increased blood volume leaving the right ventricle (2,3). TAPSE and RVFWS reduction induced by worsening of RV contractile function can therefore be attenuated by simultaneous aggravation of TR. Because changes in inferior vena cava size were the strongest predictor of outcome in the Wright et al. (1) study, TR might indeed have had a significant impact on RV wall motion.
Load dependency of RV function underlines the need for RV assessment in relation to loading conditions, particularly in PAH. Nonetheless, changes over time in variables incorporating either longitudinal displacement and load (TAPSE/pulmonary artery systolic pressure [PASP]) or longitudinal shortening and load (RVFWS/PASP) were not outcome predictors in the Wright et al. (1) study. This is because at a given vascular resistance, not only ventricular wall motion and myocardial deformation but also the developed systolic pressure depend on myocardial contractility, and therefore a reduction of RV pump function will also result in a reduction of PASP. The higher prevalence of TR in patients developing RV failure will also affect TAPSE and RVFWS, which can remain stable or even increase (“pseudonormalization”) in patients with severe TR (3). Thus, TAPSE/PASP and RVFWS/PASP become unsuitable for PAH surveillance. The use of the simplified RV contraction-pressure index instead of TAPSE/PASP might be more helpful. The simplified RV contraction-pressure index, derived as TAPSE ⋅ ΔPRV-RA, where ΔPRV-RA is the pressure gradient between the right ventricle and the right atrium, has proved to be an easy obtainable echocardiographic surrogate of the catheter-derived RV stroke work index for the assessment of RV work load (4). Similarly, also the use of RVFWS ⋅ ΔPRV-RA as a measure of RV work load instead of RVFWS/PASP might be more useful for surveillance of RV function and RV adaptability to load. At a given vascular resistance, a reduction of RV pump function with increasing TR will always result in reduction of ΔPRV-RA. Accordingly, both TAPSE ⋅ ΔPRV-RA and RVFWS ⋅ ΔPRV-RA will decrease even if TAPSE and RVFWS reductions related to RV contractile dysfunction are attenuated or even nullified by severe TR (Figure 1). In this respect, there is evidence that the RV load–corrected peak global systolic longitudinal strain rate (PSSrL ⋅ ΔPRV-RA), which includes the velocity of myocardial shortening and load, can predict in patients with PAH both the development of RV failure and RV failure–free outcomes during the next 1 to 3 years (2).
The role of echocardiography for surveillance of patients with PAH will increase in the future, but there are many aspects that must be clarified in further studies.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation
- Wright L.,
- Dwyer N.,
- Wahi S.,
- Marwick T.H.
- Dandel M.,
- Knosalla C.,
- Kemper D.,
- et al.
- Dandel M.,
- Hetzer R.
- Frea S.,
- Bovolo V.,
- Bergerone S.,
- et al.