Accurate assessment of load-independent right ventricular systolic function in patients with pulmonary hypertension

Right Ventricular Pressure Waveform Analysis-Clinical Relevance and Future Directions

Continuous measurement of pressure in the right atrium and pulmonary artery has commonly been used to monitor right ventricular function in critically ill and surgical patients. This approach is largely based upon the assumption that right atrial and pulmonary arterial pressures provide accurate surrogates for diastolic filling and peak right ventricular pressures, respectively. However, due to both technical and physiologic factors, this assumption is not always true. Accordingly, recent studies have begun to emphasize the potential clinical value of also measuring right ventricular pressure at the bedside. This has highlighted both past and emerging research demonstrating the utility of analyzing not only the amplitude of right ventricular pressure but also the shape of the pressure waveform. This brief review summarizes data demonstrating that combining conventional measurements of right ventricular pressure with variables derived from waveform shape allows for more comprehensive and ideally continuous bedside assessment of right ventricular function, particularly when combined with stroke volume measurement or 3D echocardiography, and discusses the potential use of right ventricular pressure analysis in computational models for evaluating cardiac function.

The effects of percutaneous branch pulmonary artery interventions in biventricular congenital heart disease: study protocol for a randomized controlled Dutch multicenter interventional trial

BACKGROUND

Branch pulmonary artery (PA) stenosis is one of the most common indications for percutaneous interventions in patients with transposition of the great arteries (TGA), tetralogy of Fallot (ToF), and truncus arteriosus (TA). However, the effects of percutaneous branch PA interventions on exercise capacity remains largely unknown. In addition, there is no consensus about the optimal timing of the intervention for asymptomatic patients according to international guidelines. This trial aims to identify the effects of percutaneous interventions for branch PA stenosis on exercise capacity in patients with TGA, ToF, and TA. In addition, it aims to assess the effects on RV function and to define early markers for RV adaptation and RV dysfunction to improve timing of these interventions.

METHODS

This is a randomized multicenter interventional trial. TGA, ToF, and TA patients ≥ 8 years with a class IIa indication for percutaneous branch PA intervention according to international guidelines are eligible to participate. Patients will be randomized into the intervention group or the control group (conservative management for 6 months). All patients will undergo transthoracic echocardiography, cardiac magnetic resonance (CMR) imaging, and cardiopulmonary exercise testing at baseline, 6 months, and 2-4 years follow-up. Quality of life (QoL) questionnaires will be obtained at baseline, 2 weeks post intervention or a similar range for the control group, and 6 months follow-up. The primary outcome is exercise capacity expressed as maximum oxygen uptake (peak VO2 as percentage of predicted). A total of 56 patients (intervention group n = 28, control group n = 28) is required to demonstrate a 14% increase in maximum oxygen uptake (peak VO2 as percentage of predicted) in the interventional group compared to the control group (power 80%, overall type 1 error controlled at 5%). Secondary outcomes include various parameters for RV systolic function, RV functionality, RV remodeling, procedural success, complications, lung perfusion, and QoL.

DISCUSSION

This trial will investigate the effects of percutaneous branch PA interventions on exercise capacity in patients with TGA, ToF, and TA and will identify early markers for RV adaptation and RV dysfunction to improve timing of the interventions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05809310. Registered on March 15, 2023.

Tricuspid regurgitation in pulmonary arterial hypertension: a right ventricular volumetric and functional analysis

BACKGROUND

The consequences of tricuspid regurgitation (TR) for right ventricular (RV) function and prognosis in pulmonary arterial hypertension (PAH) are poorly described and effects of tricuspid valve repair on the RV are difficult to predict.

METHODS

In 92 PAH patients with available cardiac magnetic resonance (CMR) studies, TR volume was calculated as the difference between RV stroke volume and forward stroke volume, i.e. pulmonary artery (PA) stroke volume. Survival was estimated from the time of the CMR scan to cardiopulmonary death or lung transplantation. In a subgroup, pressure-volume loop analysis including two-parallel elastances was applied to evaluate effective elastances, including net afterload (effective arterial elastance (E a)), forward afterload (effective pulmonary arterial elastance (E pa)) and backward afterload (effective tricuspid regurgitant elastance (E TR)). The effects of tricuspid valve repair were simulated using the online software package Harvi.

RESULTS

26% of PAH patients had a TR volume ≥30 mL. Greater TR volume was associated with increased N-terminal pro-brain natriuretic peptide (p=0.018), mean right atrial pressure (p<0.001) and RV end-systolic and -diastolic volume (both p<0.001). TR volume ≥30 mL was associated with a poor event-free survival (p=0.008). In comparison to E a, E pa correlated better with indices of RV dysfunction. Lower end-systolic elastance (E es) (p=0.002) and E TR (p=0.030), higher E pa (p=0.001) and reduced E es/E pa (p<0.001) were found in patients with a greater TR volume. Simulations predicted that tricuspid valve repair increases RV myocardial oxygen consumption in PAH patients with severe TR and low E es unless aggressive volume reduction is accomplished.

CONCLUSIONS

In PAH, TR has prognostic significance and is associated with low RV contractility and RV-PA uncoupling. However, haemodynamic simulations showed detrimental consequences of tricuspid valve repair in PAH patients with low RV contractility.

Right Ventricle-Pulmonary Artery Coupling in Patients Undergoing Cardiac Interventions

PURPOSE OF REVIEW

This review aims to summarize the fundamentals of RV-PA coupling, its non-invasive means of measurement, and contemporary understanding of RV-PA coupling in cardiac surgery, cardiac interventions, and congenital heart disease.

RECENT FINDINGS

The need for more accessible clinical means of evaluation of RV-PA coupling has driven researchers to investigate surrogates using cardiac MRI, echocardiography, and right-sided pressure measurements in patients undergoing cardiac surgery/interventions, as well as patients with congenital heart disease. Recent research has aimed to validate these alternative means against the gold standard, as well as establish cut-off values predictive of morbidity and/or mortality. This emerging evidence lays the groundwork for identifying appropriate RV-PA coupling surrogates and integrating them into perioperative clinical practice.

Advanced hemodynamic and cluster analysis for identifying novel RV function subphenotypes in patients with pulmonary hypertension

BACKGROUND

Quantifying right ventricular (RV) function is important to describe the pathophysiology of in pulmonary hypertension (PH). Current phenotyping strategies in PH rely on few invasive hemodynamic parameters to quantify RV dysfunction severity. The aim of this study was to identify novel RV phenotypes using unsupervised clustering methods on advanced hemodynamic features of RV function.

METHODS

Participants were identified from the University of Arizona Pulmonary Hypertension Registry (n = 190). RV-pulmonary artery coupling (Ees/Ea), RV systolic (Ees), and diastolic function (Eed) were quantified from stored RV pressure waveforms. Consensus clustering analysis with bootstrapping was used to identify the optimal clustering method. Pearson correlation analysis was used to reduce collinearity between variables. RV cluster subphenotypes were characterized using clinical data and compared to pulmonary vascular resistance (PVR) quintiles.

RESULTS

Five distinct RV clusters (C1-C5) with distinct RV subphenotypes were identified using k-medoids with a Pearson distance matrix. Clusters 1 and 2 both have low diastolic stiffness (Eed) and afterload (Ea) but RV-PA coupling (Ees/Ea) is decreased in C2. Intermediate cluster (C3) has a similar Ees/Ea as C2 but with higher PA pressure and afterload. Clusters C4 and C5 have increased Eed and Ea but C5 has a significant decrease in Ees/Ea. Cardiac output was high in C3 distinct from the other clusters. In the PVR quintiles, contractility increased and stroke volume decreased as a function of increased afterload. World Symposium PH classifications were distributed across clusters and PVR quintiles.

CONCLUSIONS

RV-centric phenotyping offers an opportunity for a more precise-medicine-based management approach.

Extracellular Matrix Instability and Chronic Inflammation Underlie Maladaptive Right Ventricular Pressure Overload Remodeling and Failure in Male Mice

Background

Right ventricular dysfunction (RVD) portends increased death risk for heart failure (HF) and pulmonary arterial hypertension (PAH) patients, regardless of left ventricular function or etiology. In both, RVD arises from the chronic RV pressure overload, and represents advanced cardiopulmonary disease. RV remodeling responses and survival rates of HF and PAH patients, however, differ by sex. Men develop more severe RVD and die at younger ages than do women. Mechanistic details of this sexual dimorphism in RV remodeling are incompletely understood. We sought to elucidate the cardiac pathophysiology underlying the sex-specific RV remodeling phenotypes, RV failure (RVF) versus compensated RVD.

Methods

We subjected male (M-) and female (F-) adult mice to moderate pulmonary artery banding (PAB) for 9wks. Mice underwent serial echocardiography, cardiac MRI, RV pressure-volume loop recordings, histologic and molecular analyses.

Results

M-PAB developed severe RVD with RVF, increased RV collagen deposition and degradation, extracellular matrix (ECM) instability, and activation and recruitment of macrophages. Despite the same severity and chronicity of RV pressure overload, F-PAB had more stable ECM, lacked chronic inflammation, and developed mild RVD without RVF.

Conclusions

ECM destabilization and chronic activation of recruited macrophages are associated with maladaptive RV remodeling and RVF in male PAB mice. Adaptive RV remodeling of female PAB mice lacked these histopathologic changes. Our findings suggest that these two pathophysiologic processes likely contribute to the sexual dimorphism of RV pressure overload remodeling. Further mechanistic studies are needed to assess their pathogenic roles and potential as targets for RVD therapy and RVF prevention.

CLINICAL PERSPECTIVE

What is new?: In a mouse model of pure PH, males but not females showed an association between ECM instability, chronic inflammation with activation of recruited macrophages, and severe RV dysfunction and failure.What are the clinical implications?: In male HF and PH patients, enhancing ECM stability and countering the recruitment and activation of macrophages may help preserve RV function such that RVF can be prevented or delayed. Further preclinical mechanistic studies are needed to assess the therapeutic potential of such approaches.

RESEARCH PERSPECTIVE

What new question does this study raise? What question should be addressed next?: What mechanisms regulate RV ECM stability and macrophage recruitment and activation in response to chronic RV pressure overload? Are these regulatory mechanisms dependent upon or independent of sex hormone signaling?

Long-term effects of pulmonary endarterectomy on pulmonary hemodynamics, cardiac function, and exercise capacity in chronic thromboembolic pulmonary hypertension

BACKGROUND

Long-term changes in exercise capacity and cardiopulmonary hemodynamics after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH) have been poorly described.

METHODS

We analyzed the data from 2 prospective surgical CTEPH cohorts in Hammersmith Hospital, London, and Amsterdam UMC. A structured multimodal follow-up was adopted, consisting of right heart catheterization, cardiac magnetic resonance imaging, and cardiopulmonary exercise testing before and after PEA. Preoperative predictors of residual pulmonary hypertension (PH; mean pulmonary artery pressure >20 mm Hg and pulmonary vascular resistance ≥2 WU) and long-term exercise intolerance (VO2max <80%) at 18 months were analyzed.

RESULTS

A total of 118 patients (61 from London and 57 from Amsterdam) were included in the analysis. Both cohorts displayed a significant improvement of pulmonary hemodynamics, right ventricular (RV) function, and exercise capacity 6 months after PEA. Between 6 and 18 months after PEA, there were no further improvements in hemodynamics and RV function, but the proportion of patients with impaired exercise capacity was high and slightly increased over time (52%-59% from 6 to 18 months). Long-term exercise intolerance was common and associated with preoperative diffusion capacity for carbon monoxide (DLCO), preoperative mixed venous oxygen saturation, and postoperative PH and right ventricular ejection fraction (RVEF). Clinically significant RV deterioration (RVEF decline >3%; 5 [9%] of 57 patients) and recurrent PH (5 [14%] of 36 patients) rarely occurred beyond 6 months after PEA. Age and preoperative DLCO were predictors of residual PH post-PEA.

CONCLUSIONS

Restoration in exercise tolerance, cardiopulmonary hemodynamics, and RV function occurs within 6 months. No substantial changes occurred between 6 and 18 months after PEA in the Amsterdam cohort. Nevertheless, long-term exercise intolerance is common and associated with postoperative RV function.

Exploratory analysis of the accuracy of echocardiographic parameters for the assessment of right ventricular function and right ventricular-pulmonary artery coupling

Echocardiography is a widely used modality for the assessment of right ventricular (RV) function; however, few studies have comprehensively compared the accuracy of echocardiographic parameters using invasively obtained reference values. Therefore, this exploratory study aimed to compare the accuracy of echocardiographic parameters of RV function and RV-pulmonary artery (PA) coupling. We calculated four indices of RV function (end-systolic elastance [Ees] for systolic function [contractility], τ for relaxation, and β and end-diastolic elastance [Eed] for stiffness), and an index of RV-PA coupling (Ees/arterial elastance [Ea]), using pressure catheterization, cardiac magnetic resonance imaging, and a single-beat method. We then compared the correlations of RV indices with echocardiographic parameters. In 63 participants (54 with pulmonary hypertension (PH) and nine without PH), Ees and τ correlated with several echocardiographic parameters, such as RV diameter and area, but the correlations were moderate (|correlation coefficients (ρ)| < 0.5 for all parameters). The correlations of β and Eed with echocardiographic parameters were weak, with |ρ| < 0.4. In contrast, Ees/Ea closely correlated with RV free wall longitudinal strain (RVFW-LS)/estimated systolic PA pressure (eSPAP) (ρ = -0.72). Ees/Ea also correlated with tricuspid annular plane systolic excursion/eSPAP, RV diameter, and RV end-systolic area, with |ρ | >0.65. In addition, RVFW-LS/eSPAP yielded high sensitivity (0.84) and specificity (0.75) for detecting reduced Ees/Ea. The present study indicated a limited accuracy of echocardiographic parameters in assessing RV systolic and diastolic function. In contrast to RV function, they showed high accuracy for assessing RV-PA coupling, with RVFW-LS/eSPAP exhibiting the highest accuracy.

Right ventricle-pulmonary artery coupling in pulmonary artery hypertension its measurement and pharmacotherapy

The right ventricular (RV) function correlates with prognosis in severe pulmonary artery hypertension (PAH) but which metric of it is most clinically relevant is still uncertain. Clinical methods to estimate RV function from simplified pressure volume loops correlate with disease severity but the clinical relevance has not been assessed. Evaluation of right ventricle pulmonary artery coupling in pulmonary hypertensive patients may help to elucidate the mechanisms of right ventricular failure and may also help to identify patients at risk or guide the timing of therapeutic interventions in pulmonary hypertension. Complete evaluation of RV failure requires echocardiographic or magnetic resonance imaging, and right heart catheterization measurements. Treatment of RV failure in PAH relies on decreasing afterload with drugs targeting pulmonary circulation; fluid management to optimize ventricular diastolic interactions; and inotropic interventions to reverse cardiogenic shock. The ability to relate quantitative metrics of RV function in pulmonary artery hypertension to clinical outcomes can provide a powerful tool for management. Such metrics could also be utilized in the future as surrogate endpoints for outcomes and evaluation of response to therapies. This review of literature gives an insight on RV-PA coupling associated with PAH, its types of measurement and pharmacological treatment.

Mathematical analysis of left ventricular elastance with respect to afterload change during ejection phase

Since the left ventricle (LV) has pressure (Plv) and volume (Vlv), we can define LV elastance from the ratio between Plv and Vlv, termed as "instantaneous elastance." On the other hand, end-systolic elastance (Emax) is known to be a good index of LV contractility, which is measured by the slope of several end-systolic Plv-Vlv points obtained by using different loads. The word Emax originates from the assumption that LV elastance increases during the ejection phase and attains its maximum at the end-systole. From this concept, we can define another elastance determined by the slope of isochronous Plv-Vlv points, that is Plv-Vlv points at a certain time after the ejection onset time by using different loads. We refer to this elastance as "load-dependent elastance." To reveal the relation between these two elastances, we used a hemodynamic model that included a detailed ventricular myocyte contraction model. From the simulation results, we found that the isochronous Plv-Vlv points lay in one line and that the line slope corresponding to the load-dependent elastance slightly decreased during the ejection phase, which is quite different from the instantaneous elastance. Subsequently, we analyzed the mechanism determining these elastances from the model equations. We found that instantaneous elastance is directly related to contraction force generated by the ventricular myocyte, but the load-dependent elastance is determined by two factors: one is the transient characteristics of the cardiac cell, i.e., the velocity-dependent force drops characteristics in instantaneous shortening. The other is the force-velocity relation of the cardiac cell. We also found that the linear isochronous pressure-volume relation is based on the approximately linear relation between the time derivative of the cellular contraction force and the cellular shortening velocity that results from the combined characteristics of LV and aortic compliances.

Echocardiography assessment of right ventricular-pulmonary artery coupling: Validation of surrogates and clinical utilities

Right ventricular-pulmonary artery (RV-PA) coupling indicates efficiency of energy transfer from the right ventricle to the pulmonary circulation. The gold standard measurement, end-systolic elastance/arterial elastance ratio (Ees/Ea), is derived from invasive pressure-volume loop, which is technically demanding, expensive and limited in clinical practice. Recent studies have proposed various non-invasive surrogates of Ees/Ea based on echocardiography assessment, of which TAPSE/PASP ratio is an easily-obtained and validated parameter in severe pulmonary hypertension and rapidly applicated in the diagnosis and risk evaluation of various diseases and cardiac intervention. In this review, we summarized principles and validations of echocardiographic surrogates, and their clinical utilities and also limitations. The goal is to systematically review the research advances of echocardiography assessment of RV-PA coupling and help to guide clinical practice.

Comparison of prognostic value among echocardiographic surrogates of right ventricular-pulmonary arterial coupling: A three-dimensional echocardiographic study

OBJECTIVES

Right ventricular (RV)-pulmonary arterial (PA) coupling is important in various cardiac diseases. Recently, several echocardiographic surrogates for RV-PA coupling have been proposed and reported to be useful in predicting outcomes. However, it remains unclear which surrogate is the most clinically relevant. This study aimed to comprehensively compare the prognostic value of different echocardiographic RV-PA coupling surrogates.

METHODS

We retrospectively reviewed 242 patients with various cardiac conditions who underwent comprehensive transthoracic echocardiography with three-dimensional RV data. In addition to conventional parameters including tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC), and PA systolic pressure (PASP), we analyzed RV free wall and global longitudinal strain (FWLS and GLS). We also obtained RV ejection fraction (RVEF), stroke volume (SV), and end-systolic volume (ESV) using three-dimensional RV analysis. RV-PA coupling surrogates were calculated as TAPSE/PASP, FAC/PASP, FWLS/PASP, GLS/PASP, RVEF/PASP, and SV/ESV. The study endpoint was a composite outcome of all-cause death or cardiovascular hospitalization within 1 year.

RESULTS

In multivariable analysis, all the RV-PA coupling surrogates were independent predictors of the outcome. Among the surrogates, the model with TAPSE/PASP showed the lowest prognostic value in model fit and discrimination ability, whereas the model with RVEF/PASP exhibited the highest prognostic value. The partial likelihood ratio test indicated that the model with RVEF/PASP was significantly better than the model with TAPSE/PASP (p < .024).

CONCLUSION

All the RV-PA coupling surrogates were independent predictors of the outcome. Notably, RVEF/PASP had the highest prognostic value among the surrogates.

The Right Ventricle in Pulmonary Hypertension

The right ventricle plays a pivotal role in patients with pulmonary hypertension (PH). Its adaptation to pressure overload determines a patient's functional status as well as survival. In a healthy situation, the right ventricle is part of a low pressure, high compliance system. It is built to accommodate changes in preload, but not very well suited for dealing with pressure overload. In PH, right ventricular (RV) contractility must increase to maintain cardiac output. In other words, the balance between the degree of RV contractility and afterload determines stroke volume. Hypertrophy is one of the major hallmarks of RV adaptation, but it may cause stiffening of the ventricle in addition to intrinsic changes to the RV myocardium. Ventricular filling becomes more difficult for which the right atrium tries to compensate through increased stroke work. Interaction of RV diastolic stiffness and right atrial (RA) function determines RV filling, but also causes vena cava backflow. Assessment of RV and RA function is critical in the evaluation of patient status. In recent guidelines, this is acknowledged by incorporating additional RV parameters in the risk stratification in PH. Several conventional parameters of RV and RA function have been part of risk stratification for many years. Understanding the pathophysiology of RV failure and the interactions with the pulmonary circulation and right atrium requires consideration of the unique RV anatomy. This review will therefore describe normal RV structure and function and changes that occur during adaptation to increased afterload. Consequences of a failing right ventricle and its implications for RA function will be discussed. Subsequently, we will describe RV and RA assessment in clinical practice.

Clinical Value of a Novel Three-Dimensional Echocardiography-Derived Index of Right Ventricle-Pulmonary Artery Coupling in Tricuspid Regurgitation

BACKGROUND

Echocardiographic surrogates of right ventricle-to-pulmonary artery (RV-PA) coupling have been reported to be associated with outcomes in patients with secondary tricuspid regurgitation (STR). However, pulmonary artery systolic pressure (PASP) is difficult to estimate using echocardiography in patients with severe STR. The aim of the present study was to evaluate the predictive power of a surrogate of RV-PA coupling obtained using right ventricular (RV) volumes measured on three-dimensional echocardiography.

METHODS

One hundred eight patients (mean age, 73 ± 13 years; 61% women) with moderate or severe STR were included.

RESULTS

At a median follow-up of 24 months (interquartile range, 2-48 months), 72 patients (40%) had reached the composite end point of death of any cause and heart failure hospitalization. RV-PA coupling was computed as the ratio between RV forward stroke volume (SV) (i.e., RV SV - regurgitant volume) and RV end-systolic volume (ESV). RV forward SV/ESV was significantly more related to the composite end point than RV ejection fraction (area under the curve, 0.85 [95% CI, 0.78-0.93] vs 0.73 [95% CI, 0.64-0.83], respectively; P = .03). A value of 0.40 was found to best correlate with outcome. On multivariate Cox regression, RV forward SV/ESV, tricuspid annular plane systolic excursion/PASP, and RV free wall longitudinal strain/PASP were all independently associated with the occurrence of the composite end point when added to a group of parameters including STR severity (severe vs moderate), atrial fibrillation, pulmonary arterial hypertension, right atrial volume, RV end-diastolic volume, and RV free wall longitudinal strain. RV forward SV/ESV < 0.40 (HR, 3.36; 95% CI, 1.49-7.56; P < .01) carried higher related risk than RV free wall longitudinal strain/PASP < -0.42%/mm Hg (HR, 3.1; 95% CI, 1.26-7.84; P = .01) and tricuspid annular plane systolic excursion/PASP < 0.36 mm/mm Hg (HR, 2.69; 95% CI, 1.29-5.58; P = .01). RV ejection fraction did not correlate independently with prognosis when added to the same group of variables.

CONCLUSIONS

RV forward SV/ESV is associated with the risk for death and heart failure hospitalization in patients with STR.

Integrating Right Ventricular Pressure Waveform Analysis With Two-Point Volume Measurement for Quantification of Systolic and Diastolic Function: Experimental Validation and Clinical Application

OBJECTIVE

To define in an experimental model the variance, accuracy, precision, and concordance of single-beat measures of right ventricular (RV) contractility and diastolic capacitance relative to conventional reference standards, and apply the methods to a clinical data set.

DESIGN

A retrospective, observational analysis of recorded pressure waveforms and RV volume measurements.

SETTING

At a university laboratory.

PARTICIPANTS

Archived data from previous studies of anesthetized swine and awake patients undergoing clinically-indicated right-heart catheterization.

INTERVENTIONS

Recording of RV pressure with simultaneous measurement of RV volume by conductance (swine) or 3-dimensional (3D) echocardiography (humans) during changes in contractility and/or loading conditions.

MEASUREMENTS AND MAIN RESULTS

Using experimental data, single-beat measures of RV contractility quantified as end-systolic elastance, and diastolic capacitance quantified as the predicted volume at an end-diastolic pressure of 15 mmHg (V15), were compared to multi-beat, preload- variant, reference standards using correlation, Bland-Altman analysis, and 4-quadrant concordance testing. This analysis indicated that the methods were not directly interchangeable with reference standards, but were sufficiently robust to suggest potential clinical utility. Clinical application supported this potential by demonstrating enhanced assessment of the response to inhaled nitric oxide in patients undergoing diagnostic right-heart catheterization.

CONCLUSIONS

Study results supported the possibility of integrating automated RV pressure analysis with RV volume measured by 3D echocardiography to create a comprehensive assessment of RV systolic and diastolic function at the bedside.

Pathophysiology of the right ventricle in health and disease: an update

The contribution of the right ventricle (RV) to cardiac output is negligible in normal resting conditions when pressures in the pulmonary circulation are low. However, the RV becomes relevant in healthy subjects during exercise and definitely so in patients with increased pulmonary artery pressures both at rest and during exercise. The adaptation of RV function to loading rests basically on an increased contractility. This is assessed by RV end-systolic elastance (Ees) to match afterload assessed by arterial elastance (Ea). The system has reserve as the Ees/Ea ratio or its imaging surrogate ejection fraction has to decrease by more than half, before the RV undergoes an increase in dimensions with eventual increase in filling pressures and systemic congestion. RV-arterial uncoupling is accompanied by an increase in diastolic elastance. Measurements of RV systolic function but also of diastolic function predict outcome in any cause pulmonary hypertension and heart failure with or without preserved left ventricular ejection fraction. Pathobiological changes in the overloaded RV include a combination of myocardial fibre hypertrophy, fibrosis and capillary rarefaction, a titin phosphorylation-related displacement of myofibril tension-length relationships to higher pressures, a metabolic shift from mitochondrial free fatty acid oxidation to cytoplasmic glycolysis, toxic lipid accumulation, and activation of apoptotic and inflammatory signalling pathways. Treatment of RV failure rests on the relief of excessive loading.

Pressure Overload and Right Ventricular Failure: From Pathophysiology to Treatment

Right ventricular failure (RVF) is often caused by increased afterload and disrupted coupling between the right ventricle (RV) and the pulmonary arteries (PAs). After a phase of adaptive hypertrophy, pressure-overloaded RVs evolve towards maladaptive hypertrophy and finally ventricular dilatation, with reduced stroke volume and systemic congestion. In this article, we review the concept of RV-PA coupling, which depicts the interaction between RV contractility and afterload, as well as the invasive and non-invasive techniques for its assessment. The current principles of RVF management based on pathophysiology and underlying etiology are subsequently discussed. Treatment strategies remain a challenge and range from fluid management and afterload reduction in moderate RVF to vasopressor therapy, inotropic support and, occasionally, mechanical circulatory support in severe RVF.

A new assessment method for right ventricular diastolic function using right heart catheterization by pressure-volume loop

Diastolic stiffness coefficient (β) and end-diastolic elastance (Eed) are ventricular-specific diastolic parameters. However, the diastolic function of right ventricle had not been investigated sufficiently due to the lack of established evaluation method. We evaluated the validity of these parameters calculated using only data of right heart catheterization (RHC) and assessed it in patients with restrictive cardiomyopathy (RCM) and cardiac amyloidosis. We retrospectively analyzed 46 patients with heart failure who underwent RHC within 10 days of cardiac magnetic resonance (CMR). Right ventricular end-diastolic volume and end-systolic volume were calculated using only RHC data, which were found to be finely correlated with those obtained from CMR. β and Eed calculated by this method were also significantly correlated with those derived from conventional method using CMR. By this method, β and Eed were significantly higher in RCM with amyloidosis group than dilated cardiomyopathy group. In addition, the β and Eed calculated by our method were finely correlated with E/A ratio on echocardiography. We established an easy method to estimate β and Eed of right ventricle from only RHC. The method finely demonstrated right ventricular diastolic dysfunction in patients with RCM and amyloidosis.

Impact of Pulmonary Arterial Elastance on Right Ventricular Mechanics and Exercise Capacity in Repaired Tetralogy of Fallot

BACKGROUND AND OBJECTIVES

Pathophysiological changes of right ventricle (RV) after repair of tetralogy of Fallot (TOF) are coupled with a highly compliant low-pressure pulmonary artery (PA) system. This study aimed to determine whether pulmonary vascular function was associated with RV parameters and exercise capacity, and its impact on RV remodeling after pulmonary valve replacement.

METHODS

In a total of 48 patients over 18 years of age with repaired TOF, pulmonary arterial elastance (Ea), RV volume data, and RV-PA coupling ratio were calculated and analyzed in relation to exercise capacity.

RESULTS

Patients with a low Ea showed a more severe pulmonary regurgitation volume index, greater RV end-diastolic volume index, and greater effective RV stroke volume (p=0.039, p=0.013, and p=0.011, respectively). Patients with a high Ea had lower exercise capacity than those with a low Ea (peak oxygen consumption [peak VO₂] rate: 25.8±7.7 vs. 34.3±5.5 mL/kg/min, respectively, p=0.003), while peak VO₂ was inversely correlated with Ea and mean PA pressure (p=0.004 and p=0.004, respectively). In the univariate analysis, a higher preoperative RV end-diastolic volume index and RV end-systolic volume index, left ventricular end-systolic volume index, and higher RV-PA coupling ratio were risk factors for suboptimal outcomes. Preoperative RV volume and RV-PA coupling ratio reflecting the adaptive PA system response are important factors in optimal postoperative results.

CONCLUSIONS

We found that PA vascular dysfunction, presenting as elevated Ea in TOF, may contribute to exercise intolerance. However, Ea was inversely correlated with pulmonary regurgitation (PR) severity, which may prevent PR, RV dilatation, and left ventricular dilatation in the absence of significant pulmonary stenosis.

Adaptive versus maladaptive right ventricular remodelling

Right ventricular (RV) function and its adaptation to increased afterload [RV-pulmonary arterial (PA) coupling] are crucial in various types of pulmonary hypertension, determining symptomatology and outcome. In the course of disease progression and increasing afterload, the right ventricle undergoes adaptive remodelling to maintain right-sided cardiac output by increasing contractility. Exhaustion of compensatory RV remodelling (RV-PA uncoupling) finally leads to maladaptation and increase of cardiac volumes, resulting in heart failure. The gold-standard measurement of RV-PA coupling is the ratio of contractility [end-systolic elastance (Ees)] to afterload [arterial elastance (Ea)] derived from RV pressure-volume loops obtained by conductance catheterization. The optimal Ees/Ea ratio is between 1.5 and 2.0. RV-PA coupling in pulmonary hypertension has considerable reserve; the Ees/Ea threshold at which uncoupling occurs is estimated to be ~0.7. As RV conductance catheterization is invasive, complex, and not widely available, multiple non-invasive echocardiographic surrogates for Ees/Ea have been investigated. One of the first described and best validated surrogates is the ratio of tricuspid annular plane systolic excursion to estimated pulmonary arterial systolic pressure (TAPSE/PASP), which has shown prognostic relevance in left-sided heart failure and precapillary pulmonary hypertension. Other RV-PA coupling surrogates have been formed by replacing TAPSE with different echocardiographic measures of RV contractility, such as peak systolic tissue velocity of the lateral tricuspid annulus (S'), RV fractional area change, speckle tracking-based RV free wall longitudinal strain and global longitudinal strain, and three-dimensional RV ejection fraction. PASP-independent surrogates have also been studied, including the ratios S'/RV end-systolic area index, RV area change/RV end-systolic area, and stroke volume/end-systolic volume. Limitations of these non-invasive surrogates include the influence of severe tricuspid regurgitation (which can cause distortion of longitudinal measurements and underestimation of PASP) and the angle dependence of TAPSE and PASP. Detection of early RV remodelling may require isolated analysis of single components of RV shortening along the radial and anteroposterior axes as well as the longitudinal axis. Multiple non-invasive methods may need to be applied depending on the level of RV dysfunction. This review explains the mechanisms of RV (mal)adaptation to its load, describes the invasive assessment of RV-PA coupling, and provides an overview of studies of non-invasive surrogate parameters, highlighting recently published works in this field. Further large-scale prospective studies including gold-standard validation are needed, as most studies to date had a retrospective, single-centre design with a small number of participants, and validation against gold-standard Ees/Ea was rarely performed.

Clinical Usefulness of Right Ventricle-Pulmonary Artery Coupling in Cardiovascular Disease

Right ventricular-pulmonary artery coupling (RV-PA coupling) refers to the relationship between RV contractility and RV afterload. Normal RV-PA coupling is maintained only when RV function and pulmonary vascular resistance are appropriately matched. RV-PA uncoupling occurs when RV contractility cannot increase to match RV afterload, resulting in RV dysfunction and right heart failure. RV-PA coupling plays an important role in the pathophysiology and progression of cardiovascular diseases. Therefore, early and accurate evaluation of RV-PA coupling is of great significance for a patient's condition assessment, clinical decision making, risk stratification, and prognosis judgment. RV-PA coupling can be assessed by using invasive or noninvasive approaches. The aim of this review was to summarize the pathological mechanism and evaluation methods of RV-PA coupling, the advantages and disadvantages of each method, and the application value of RV-PA coupling in various cardiovascular diseases.

Right Ventricular Limitation: A Tale of Two Elastances

Right ventricular (RV) dysfunction is a commonly considered cause of low cardiac output in critically ill patients. Its management can be difficult and requires an understanding of how the RV limits cardiac output. We explain that RV stroke output is caught between the passive elastance of the RV walls during diastolic filling and the active elastance produced by the RV in systole. These two elastances limit RV filling and stroke volume and consequently limit left ventricular stroke volume. We emphasize the use of the term "RV limitation" and argue that limitation of RV filling is the primary pathophysiological process by which the RV causes hemodynamic instability. Importantly, RV limitation can be present even when RV function is normal. We use the term "RV dysfunction" to indicate that RV end-systolic elastance is depressed or diastolic elastance is increased. When RV dysfunction is present, RV limitation occurs at lowerpulmonary valve opening pressures and lower stroke volume, but stroke volume and cardiac output still can be maintained until RV filling is limited. We use the term "RV failure" to indicate the condition in which RV output is insufficient for tissue needs. We discuss the physiological underpinnings of these terms and implications for clinical management.

Right Ventricular Function During Exercise After Pulmonary Endarterectomy for Chronic Thromboembolic Pulmonary Hypertension

Background Pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension improves resting hemodynamics and right ventricular (RV) function. Because exercise tolerance frequently remains impaired, RV function may not have completely normalized after PEA. Therefore, we performed a detailed invasive hemodynamic study to investigate the effect of PEA on RV function during exercise. Methods and Results In this prospective study, all consenting patients with chronic thromboembolic pulmonary hypertension eligible for surgery and able to perform cycle ergometry underwent cardiac magnetic resonance imaging, a maximal cardiopulmonary exercise test, and a submaximal invasive cardiopulmonary exercise test before and 6 months after PEA. Hemodynamic assessment and analysis of RV pressure curves using the single-beat method was used to determine load-independent RV contractility (end systolic elastance), RV afterload (arterial elastance), RV-arterial coupling (end systolic elastance-arterial elastance), and stroke volume both at rest and during exercise. RV rest-to-exercise responses were compared before and after PEA using 2-way repeated-measures analysis of variance with Bonferroni post hoc correction. A total of 19 patients with chronic thromboembolic pulmonary hypertension completed the entire study protocol. Resting hemodynamics improved significantly after PEA. The RV exertional stroke volume response improved 6 months after PEA (79±32 at rest versus 102±28 mL during exercise; P<0.01). Although RV afterload (arterial elastance) increased during exercise, RV contractility (end systolic elastance) did not change during exercise either before (0.43 [0.32-0.58] mm Hg/mL versus 0.45 [0.22-0.65] mm Hg/mL; P=0.6) or after PEA (0.32 [0.23-0.40] mm Hg/mL versus 0.28 [0.19-0.44] mm Hg/mL; P=0.7). In addition, mean pulmonary artery pressure-cardiac output and end systolic elastance-arterial elastance slopes remained unchanged after PEA. Conclusions The exertional RV stroke volume response improves significantly after PEA for chronic thromboembolic pulmonary hypertension despite a persistently abnormal afterload and absence of an RV contractile reserve. This may suggest that at mildly elevated pulmonary pressures, stroke volume is less dependent on RV contractility and afterload and is primarily determined by venous return and conduit function.

Concomitant Transcatheter Edge-to-Edge Treatment of Secondary Tricuspid and Mitral Regurgitation: An Expert Opinion

Secondary (functional) tricuspid regurgitation (sTR) is common in patients with mitral regurgitation (MR). Because combined valvular heart disease affects long-term survival, in comparison with isolated MR or tricuspid regurgitation, it is essential to offer patients adequate treatment. Despite considerable experience, no conclusive data are yet available on the prognostic impact of concomitant tricuspid valve surgery at the time of mitral valve surgery. Emerging transcatheter treatments offer the opportunity to treat both conditions (MR and sTR) simultaneously or in a stepwise fashion. This review provides a clinical overview on available data regarding the rationale for treatment of sTR in patients with relevant MR undergoing mitral transcatheter edge-to-edge repair, focusing on clinical and anatomical selection criteria.

Longitudinal Validation of Right Ventricular Pressure Monitoring for the Assessment of Right Ventricular Systolic Dysfunction in a Large Animal Ischemic Model

Right ventricular (RV) dysfunction is a major cause of morbidity and mortality in intensive care and cardiac surgery. Early detection of RV dysfunction may be facilitated by continuous monitoring of RV waveform obtained from a pulmonary artery catheter. The objective is to evaluate the extent to which RV pressure monitoring can detect changes in RV systolic performance assess by RV end-systolic elastance (E_es) following the development of an acute RV ischemic in a porcine model.

HYPOTHESIS

RV pressure monitoring can detect changes in RV systolic performance assess by RV E_es following the development of an acute RV ischemic model.

METHODS AND MODELS

Acute ischemic RV dysfunction was induced by progressive embolization of microsphere in the right coronary artery to mimic RV dysfunction clinically experienced during cardiopulmonary bypass separation caused by air microemboli. RV hemodynamic performance was assessed using RV pressure waveform-derived parameters and RV E_es obtained using a conductance catheter during inferior vena cava occlusions.

RESULTS

Acute ischemia resulted in a significant reduction in RV E_es from 0.26 mm Hg/mL (interquartile range, 0.16-0.32 mm Hg/mL) to 0.14 mm Hg/mL (0.11-0.19 mm Hg/mL; p < 0.010), cardiac output from 6.3 L/min (5.7-7 L/min) to 4.5 (3.9-5.2 L/min; p = 0.007), mean systemic arterial pressure from 72 mm Hg (66-74 mm Hg) to 51 mm Hg (46-56 mm Hg; p < 0.001), and mixed venous oxygen saturation from 65% (57-72%) to 41% (35-45%; p < 0.001). Linear mixed-effect model analysis was used to assess the relationship between E_es and RV pressure-derived parameters. The reduction in RV E_es best correlated with a reduction in RV maximum first derivative of pressure during isovolumetric contraction (dP/dt_max) and single-beat RV E_es. Adjusting RV dP/dt_max for heart rate resulted in an improved surrogate of RV E_es.

INTERPRETATION AND CONCLUSIONS

Stepwise decreases in RV E_es during acute ischemic RV dysfunction were accurately tracked by RV dP/dt_max derived from the RV pressure waveform.

The prognostic role of the echocardiographic tricuspid annular plane systolic excursion/systolic pulmonary arterial pressure (TAPSE/sPAP) ratio and its relationship with NT-proANP plasma level in systemic sclerosis

Background

The tricuspid annular plane systolic excursion/systolic pulmonary arterial pressure (TAPSE/sPAP) ratio is an echocardiographic estimation of the right ventricle to pulmonary artery (RV/PA) coupling, with a validated prognostic role in different clinical settings. Systemic sclerosis (SSc) patients without evident cardiovascular involvement frequently display subtle RV impairment. The amino-terminal atrial natriuretic peptide (NT-proANP) plasma level relates to SSc disease progression and mortality. We aimed to assess the prognostic value of the TAPSE/sPAP ratio and its relationship with NT-proANP plasma level in SSc patients without overt cardiovascular involvement.

Methods

We retrospectively analysed 70 SSc consecutive patients, with no clinical evidence of cardiovascular involvement or pulmonary hypertension (PH), and 30 healthy controls (HC) in a retrospective, single-centre study. All SSc patients underwent recurrent clinical and echocardiographic assessments and NT-proANP plasma level was assessed at baseline. SSc-related cardiovascular events and deaths were extracted during a 6-year follow-up. The complete work-up for the diagnosis, treatment and management of PH performed along the 6 years of follow-up referred to the 2015 European Society of Cardiology guidelines.

Results

Systemic sclerosis patients showed lower TAPSE/sPAP ratio at baseline compared to HC [SSc median value = 0.71 mm/mmHg, (IQR 0.62-0.88) vs. HC median value = 1.00 mm/mmHg, (IQR 0.96-1.05); p < 0.001]. Multivariable Cox analysis revealed TAPSE/sPAP ratio as an independent predictor for SSc-related cardiovascular events [HR = 3.436 (95% CI 1.577-7.448); p = 0.002] and mortality [HR = 3.653 (95% CI 1.712-8.892); p = 0.014]. The value of TAPSE/sPAP ratio < 0.7 mm/mmHg was identified as an optimal cut-off for predicting adverse outcomes (p < 0.001) by receiver operating characteristic (ROC) analyses. NT-proANP level significantly related to TAPSE/sPAP ratio (r = 0.52, p < 0.001). TAPSE/sPAP ratio combined with NT-proANP showed an overall significant prognostic role in this SSc population, confirmed by Kaplan-Meier analysis (Log rank p < 0.001).

Conclusion

The TAPSE/sPAP ratio, as an index of RV/PA coupling, is an affordable predictor of cardiovascular events and mortality in SSc and, combined with NT-proANP level, may improve the clinical phenotyping and prognostic stratification of SSc patients.

The atrial secondary tricuspid regurgitation is associated to more favorable outcome than the ventricular phenotype

Aim

We sought to evaluate the differences in prognosis between the atrial (A-STR) and the ventricular (V-STR) phenotypes of secondary tricuspid regurgitation.

Materials and methods

Consecutive patients with moderate or severe STR referred for echocardiography were enrolled. A-STR and V-STR were defined according to the last ACC/AHA guidelines criteria. The primary endpoint was the composite of all-cause death and heart failure (HF) hospitalizations.

Results

A total of 211 patients were enrolled. The prevalence of A-STR in our cohort was 26%. Patients with A- STR were significantly older and with lower NYHA functional class than V-STR patients. The prevalence of severe STR was similar (28% in A-STR vs. 37% in V-STR, p = 0.291). A-STR patients had smaller tenting height (TH) (10 ± 4 mm vs. 12 ± 7 mm, p = 0.023), larger end-diastolic tricuspid annulus area (9 ± 2 cm2 vs. 7 ± 6 cm2/m2, p = 0.007), smaller right ventricular (RV) end-diastolic volumes (72 ± 27 ml/m2 vs. 92 ± 38 ml/m2; p = 0.001), and better RV longitudinal function (18 ± 7 mm vs. 16 ± 6 mm; p = 0.126 for TAPSE, and −21 ± 5% vs. −18 ± 5%; p = 0.006, for RV free-wall longitudinal strain, RVFWLS) than V-STR patients. Conversely, RV ejection fraction (RVEF, 48 ± 10% vs. 46 ± 11%, p = 0.257) and maximal right atrial volumes (64 ± 38 ml/m2 vs. 55 ± 23 ml/m2, p = 0.327) were similar between the two groups. After a median follow-up of 10 months, patients with V-STR had a 2.7-fold higher risk (HR: 2.7, 95% CI 95% = 1.3–5.7) of experiencing the combined endpoint than A-STR patients. The factors related to outcomes resulted different between the two STR phenotypes: TR-severity (HR: 5.8, CI 95% = 1, 4–25, P = 0.019) in A-STR patients; TR severity (HR 2.9, 95% CI 1.4–6.3, p = 0.005), RVEF (HR: 0.97, 95% CI 0.94–0.99, p = 0.044), and RVFWLS (HR: 0.93, 95% CI 0.85–0.98, p = 0.009) in V-STR.

Conclusion

Almost one-third of patients referred to the echocardiography laboratory for significant STR have A-STR. A-STR patients had a lower incidence of the combined endpoint than V-STR patients. Moreover, while TR severity was the only independent factor associated to outcome in A-STR patients, TR severity and RV function were independently associated with outcome in V-STR patients.

Accuracy of Swan‒Ganz catheterization‐based assessment of right ventricular function: Validation study using high‐fidelity micromanometry‐derived values as reference

Right ventricular (RV) function critically affects the outcomes of patients with pulmonary hypertension (PH). Pressure wave analysis using Swan‒Ganz catheterization (SG‐cath) allows for the calculation of indices of RV function. However, the accuracy of these indices has not been validated. In the present study, we calculated indices of systolic and diastolic RV functions using SG‐cath‐derived pressure recordings in patients with suspected or confirmed PH. We analyzed and validated the accuracies of three RV indices having proven prognostic values, that is, end‐systolic elastance (Ees)/arterial elastance (Ea), β (stiffness constant), and end‐diastolic elastance (Eed), using high‐fidelity micromanometry‐derived data as reference. We analyzed 73 participants who underwent SG‐cath for the diagnosis or evaluation of PH. In this study, Ees/Ea was calculated via the single‐beat pressure method using [1.65 × (mean pulmonary arterial pressure) − 7.79] as end‐systolic pressure. SG‐cath‐derived Ees/Ea, β, and Eed were 0.89 ± 0.69 (mean ± standard deviation), 0.027 ± 0.002, and 0.16 ± 0.02 mmHg/ml, respectively. The mean differences (limits of agreement) between SG‐cath and micromanometry‐derived data were 0.13 (0.99, −0.72), 0.002 (0.020, −0.013), and 0.04 (0.20, −0.12) for Ees/Ea, β, and Eed, respectively. The intraclass correlation coefficients of the indices derived from the two catheterizations were 0.76, 0.71, and 0.57 for Ees/Ea, β, and Eed, respectively. In patients with confirmed or suspected PH, SG‐cath‐derived RV indices, especially Ees/Ea and β, exhibited a good correlation with micromanometry‐derived reference values.

Utility of Real-Time Three-Dimensional Echocardiography for the Assessment of Right Ventricular Morphology and Function in Large Animal Models

Real-time three-dimensional echocardiography (RT3DE) enables a noninvasive assessment of right ventricular (RV) morphology. However, no study has evaluated the relationship between RV function obtained by RT3DE and RV pressure-volume loops. This hypothesis-driven, experimental study aimed to assess the utility of RT3DE in the evaluation of RV morphology and function. Ten anesthetized beagle dogs sequentially underwent dobutamine infusion, acute infusion of lactated Ringer’s solution, and furosemide administration to alter RV contractility and loading conditions. RV pressure-volume loop-derived hemodynamic measurements and echocardiography, including two-dimensional speckle-tracking echocardiography and RT3DE, were performed in each study protocol. Bland−Altman analysis showed strong agreement in RV volume, ejection fraction, and stroke volume obtained by right heart catheterization and RT3DE. Multiple regression analyses revealed that the peak myocardial velocity of the lateral tricuspid annulus (RV s’) and global RV longitudinal strain rate were significantly associated with end-systolic elastance (adjusted r2 = 0.66, p < 0.001). RV s’, RV free wall longitudinal strain, and RT3DE-derived stroke volume/end-systolic RV volume ratio were associated with RV pressure-volume loops-derived end-systolic/arterial elastance ratio (adjusted r2 = 0.34, p < 0.001). RT3DE could detect the changes in catheterization-derived RV volume with a strong agreement and might be useful in estimating RV-pulmonary arterial coupling.

Pressure-based estimation of right ventricular ejection fraction

AIMS

A method for estimating right ventricular ejection fraction (RVEF) from RV pressure waveforms was recently validated in an experimental model. Currently, cardiac magnetic resonance imaging (MRI) is the clinical reference standard for measurement of RVEF in pulmonary arterial hypertension (PAH). The present study was designed to test the hypothesis that the pressure-based method can detect clinically significant reductions in RVEF as determined by cardiac MRI in patients with PAH.

METHODS AND RESULTS

RVEF estimates derived from analysis of RV pressure waveforms recorded during right heart catheterization (RHC) in 25 patients were compared with cardiac MRI measurements of RVEF obtained within 24 h. Three investigators blinded to cardiac MRI results independently performed pressure-based RVEF estimation with the mean of their results used for comparison. Linear regression was used to assess correlation, and a receiver operator characteristic (ROC) curve was derived to define ability of the pressure-based method to detect a maladaptive RV response, defined as RVEF <35% on cardiac MRI. In 23 patients, an automated adaptation of the pressure-based RVEF method was also applied as proof of concept for beat-to-beat RVEF monitoring. The study cohort was comprised of 16 female and 9 male PAH patients with an average age of 53 ± 13 years. RVEF measured by cardiac MRI ranged from 16% to 57% (mean 37.7 ± 11.6%), and estimated RVEF from 15% to 54% (mean 36.2 ± 11.2%; P = 0.6). Measured and estimated RVEF were significantly correlated (r2  = 0.78; P < 0.0001). ROC curve analysis demonstrated an area under the curve of 0.94 ± 0.04 with a sensitivity of 81% and specificity of 85% for predicting a maladaptive RV response. As a secondary outcome, with the recognized limitation of non-coincident measures, Bland-Altman analysis was performed and indicated minimal bias for estimated RVEF (-1.5%) with limits of agreement of ± 10.9%. Adaptation of the pressure-based estimation method to provide beat-to-beat RVEF also demonstrated significant correlation between the median beat-to-beat value over 10 s with cardiac MRI (r2  = 0.66; P < 0.001), and an area under the ROC curve of 0.94 ± 0.04 (CI = 0.86 to 1.00) with sensitivity and specificity of 78% and 86%, respectively, for predicting a maladaptive RV response.

CONCLUSIONS

Pressure-based estimation of RVEF correlates with cardiac MRI and detects clinically significant reductions in RVEF. Study results support potential utility of pressure-based RVEF estimation for assessing the response to diagnostic or therapeutic interventions during RHC.

Invasive Right Ventricular Pressure-Volume Analysis: Basic Principles, Clinical Applications, and Practical Recommendations

Right ventricular pressure-volume (PV) analysis characterizes ventricular systolic and diastolic properties independent of loading conditions like volume status and afterload. While long-considered the gold-standard method for quantifying myocardial chamber performance, it was traditionally only performed in highly specialized research settings. With recent advances in catheter technology and more sophisticated approaches to analyze PV data, it is now more commonly used in a variety of clinical and research settings. Herein, we review the basic techniques for PV loop measurement, analysis, and interpretation with the aim of providing readers with a deeper understanding of the strengths and limitations of PV analysis. In the second half of the review, we detail key scenarios in which right ventricular PV analysis has influenced our understanding of clinically relevant topics and where the technique can be applied to resolve additional areas of uncertainty. All told, PV analysis has an important role in advancing our understanding of right ventricular physiology and its contribution to cardiovascular function in health and disease.

Right Ventricular and Right Atrial Function Are Less Compromised in Pulmonary Hypertension Secondary to Heart Failure With Preserved Ejection Fraction: A Comparison With Pulmonary Arterial Hypertension With Similar Pressure Overload

Supplemental Digital Content is available in the text.

Background:

Heart failure with preserved ejection fraction (HFpEF) is a prevalent disorder for which no effective treatment yet exists. Pulmonary hypertension (PH) and right atrial (RA) and ventricular (RV) dysfunction are frequently observed. The question remains whether the PH with the associated RV/RA dysfunction in HFpEF are markers of disease severity.

Methods:

To obtain insight in the relative importance of pressure-overload and left-to-right interaction, we compared RA and RV function in 3 groups: 1. HFpEF (n=13); 2. HFpEF-PH (n=33), and; 3. pulmonary arterial hypertension (PAH) matched to pulmonary artery pressures of HFpEF-PH (PH limited to mPAP ≥30 and ≤50 mmHg) (n=47). Patients underwent right heart catheterization and cardiac magnetic resonance imaging.

Results:

The right ventricle in HFpEF-PH was less dilated and hypertrophied than in PAH. In addition, RV ejection fraction was more preserved (HFpEF-PH: 52±11 versus PAH: 36±12%). RV filling patterns differed: vena cava backflow during RA contraction was observed in PAH only. In HFpEF-PH, RA pressure was elevated throughout the cardiac cycle (HFpEF-PH: 10 [8–14] versus PAH: 7 [5–10] mm Hg), while RA volume was smaller, reflecting excessive RA stiffness (HFpEF-PH: 0.14 [0.10–0.17] versus PAH: 0.08 [0.06–0.11] mm Hg/mL). RA stiffness was associated with an increased eccentricity index (HFpEF-PH: 1.3±0.2 versus PAH: 1.2±0.1) and interatrial pressure gradient (9 [5 to 12] versus 2 [−2 to 5] mm Hg).

Conclusions:

RV/RA function was less compromised in HFpEF-PH than in PAH, despite similar pressure-overload. Increased RA pressure and stiffness in HFpEF-PH were explained by left atrial/RA-interaction. Therefore, our results indicate that increased RA pressure is not a sign of overt RV failure but rather a reflection of HFpEF-severity.

Assessment of right ventricle in pulmonary arterial hypertension with three-dimensional echocardiography and cardiovascular magnetic resonance

AIM

To correlate 3-D Echo and CMR RV parameters and to verify whether they are similarly related to the clinical conditions of patients with pulmonary arterial hypertension (PAH), a disease in which the RV plays a crucial prognostic role.

METHODS

We enrolled 34 consecutive PAH patients followed by our PAH clinics. All patients underwent a 3-D Echo and CMR assessment of RV volumes and functions in the same day. The presence or absence of correlation between major findings was investigated; functional RV parameters were also analyzed in relation to 6-min walking test (6MWT) results and BNP/Nt-proBNP plasma levels. Twenty-four subjects served as controls.

RESULTS

Good agreement was found between 3-D Echo and CMR measures of RV volumes [RV-end-diastolic volume (r = 0.72, P < 0.0001), RV-end-systolic volume (ESV) (r = 0.80, P < 0.0001)] and function [RV-EF (r = 0.73, P < 0.0001), RV-ESV/SV (r = 0.83, P = 0.001)] for all the subjects of the study. These correlations were stronger in PAH patients than in control subjects. Importantly, 3-D Echo and CMR RV-EF and RV to pulmonary arterial coupling (RV-ESV/SV) similarly correlated with BNP/Nt-proBNP levels and with functional capacity measured at 6MWT in the PAH patients group.

CONCLUSIONS

3-D Echo demonstrated a significant agreement with CMR in the assessment of RV volume and function in PAH patients. Both techniques showed a similar correlation with clinical and prognostic parameters. The use of 3-D Echo should be amply boosted in the real-world clinical evaluation of PAH patients.

Interplay of sex hormones and long-term right ventricular adaptation in a Dutch PAH-cohort

BACKGROUND

To investigate the association between altered sex hormone expression and long-term right ventricular (RV) adaptation and progression of right heart failure in a Dutch cohort of Pulmonary Arterial Hypertension (PAH)-patients across a wide range of ages.

METHODS

In this study we included 279 PAH-patients, of which 169 females and 110 males. From 59 patients and 21 controls we collected plasma samples for sex hormone analysis. Right heart catheterization (RHC) and/or cardiac magnetic resonance (CMR) imaging was performed at baseline. For longitudinal data analysis, we selected patients that underwent a RHC and/or CMR maximally 1.5 years prior to an event (death or transplantation, N = 49).

RESULTS

Dehydroepiandrosterone-sulfate (DHEA-S) levels were reduced in male and female PAH-patients compared to controls, whereas androstenedione and testosterone were only reduced in female patients. Interestingly, low DHEA-S and high testosterone levels were correlated to worse RV function in male patients only. Subsequently, we analyzed prognosis and RV adaptation in females stratified by age. Females ≤45years had best prognosis in comparison to females ≥55years and males. No differences in RV function at baseline were observed, despite higher pressure-overload in females ≤45years. Longitudinal data demonstrated a clear distinction in RV adaptation. Although females ≤45years had an event at a later time point, RV function was more impaired at end-stage disease.

CONCLUSIONS

Sex hormones are differently associated with RV function in male and female PAH-patients. DHEA-S appeared to be lower in male and female PAH-patients. Females ≤45years could persevere pressure-overload for a longer time, but had a more severe RV phenotype at end-stage disease.

Right atrial function is associated with RV diastolic stiffness: RA-RV interaction in pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) patients have altered right atrial (RA) function and right ventricular (RV) diastolic stiffness. This study assessed the impact of RV diastolic stiffness on RA-RV interaction.

METHODS

Low or high end-diastolic elastance (E_ed) PAH patients (n=94) were compared to controls (n=31). Treatment response was evaluated in n=62 patients. RV and RA longitudinal strain, RA emptying and RV filling were determined and diastole was divided in a passive and active phase. Vena cava backflow was calculated as RV active filling-RA active emptying; RA stroke work as RA active emptying*RV end-diastolic pressure.

RESULTS

With increased E_ed, RA and RV passive strain were reduced while active strain was preserved. In comparison to controls, patients had lower RV passive filling, but higher RA active emptying and RA stroke work. RV active filling was lower in high E_ed patients, resulting in higher vena cava backflow. Upon treatment, E_ed reduced in half of high E_edpatients, which coincided with larger reductions in afterload, RV mass and vena cava backflow and greater improvements in RV active filling and stroke volume in comparison to patients in whom E_ed remained high.

CONCLUSIONS

In PAH, RA function is associated with changes in RV function. Despite increased RA stroke work, severe RV diastolic stiffness is associated with reduced RV active filling and increased vena cava backflow. In 50% of high baseline E_ed patients, diastolic stiffness remains high, despite treatment. E_ed reduction coincided with a large reduction in afterload, increased RV active filling and decreased vena cava backflow.

The physiologic basis of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare dyspnea-fatigue syndrome caused by a progressive increase in pulmonary vascular resistance (PVR) and eventual right ventricular (RV) failure. In spite of extensive pulmonary vascular remodeling, lung function in PAH is generally well preserved, with hyperventilation and increased physiologic dead space, but minimal changes in lung mechanics and only mild to moderate hypoxemia and hypocapnia. Hypoxemia is mainly caused by a low mixed venous PO₂ from a decreased cardiac output. Hypocapnia is mainly caused by an increased chemosensitivity. Exercise limitation in PAH is cardiovascular rather than ventilatory or muscular. The extent of pulmonary vascular disease in PAH is defined by multipoint pulmonary vascular pressure-flow relationships with a correction for hematocrit. Pulsatile pulmonary vascular pressure-flow relationships in PAH allow for the assessment of RV hydraulic load. This analysis is possible either in the frequency-domain or in the time-domain. The RV in PAH adapts to increased afterload by an increased contractility to preserve its coupling to the pulmonary circulation. When this homeometric mechanism is exhausted, the RV dilates to preserve flow output by an additional heterometric mechanism. Right heart failure is then diagnosed by imaging of increased right heart dimensions and clinical systemic congestion signs and symptoms. The coupling of the RV to the pulmonary circulation is assessed by the ratio of end-systolic to arterial elastances, but these measurements are difficult. Simplified estimates of RV-PA coupling can be obtained by magnetic resonance or echocardiographic imaging of ejection fraction.

Reverse remodeling of tricuspid valve morphology and function in chronic thromboembolic pulmonary hypertension patients following pulmonary thromboendarterectomy: a cardiac magnetic resonance imaging and invasive hemodynamic study

BACKGROUND

To investigate changes in tricuspid annulus (TA) and tricuspid valve (TV) morphology among chronic thromboembolic pulmonary hypertension (CTEPH) patients before and 12 months after pulmonary thromboendarterectomy (PEA) and compare these findings to normal control subjects.

METHODS

20 CTEPH patients and 20 controls were enrolled in the study. The patients were examined with echocardiography, right heart catherization and cardiac magnetic resonance imaging prior to PEA and 12 months after.

RESULTS

Right atrium (RA) volume was significantly reduced from baseline to 12 months after PEA (30 ± 9 vs 23 ± 5 ml/m², p < 0.005). TA annular area in systole remained unchanged (p = 0.11) and was comparable to controls. The leaflet area, tenting volume and tenting height in systole were significantly increased at baseline but decreased significantly with comparable values to controls after 12 months (p < 0.005). There was correlation between the changes of right ventricular-pulmonary artery coupling and changes of TV tenting height (r = - 0.54, p = 0.02), TV tenting volume (r = - 0.73, p < 0.001) and TV leaflet area (- 0.57, p = 0.01) from baseline to 12 months after PEA. Tricuspid regurgitation jet area/RA area was significantly (p < 0.01) reduced from baseline (30 ± 13%) to 12 months after PEA (9 ± 10%).

CONCLUSION

In CTEPH patients selected for PEA, TV tenting height, volume and valve area are significantly increased whereas annulus size and shape are less affected. The alterations in TV morphology are fully reversed after PEA and correlates to improvements of right ventricular-pulmonary arterial coupling.

Right ventricular and cyclic guanosine monophosphate signalling abnormalities in stages B and C of heart failure with preserved ejection fraction

Aims

Identifying early right ventricular (RV) dysfunction and impaired vasodilator reserve is challenging in heart failure with preserved ejection fraction (HFpEF). We hypothesized that cardiac magnetic resonance (CMR)‐based exercise imaging and serial cyclic guanosine monophosphate (cGMP) measurements can identify dynamic RV‐arterial uncoupling and responsiveness to pulmonary vasodilators at early stages of the HFpEF syndrome.

Methods and results

Patients with HFpEF (n = 16), impaired left ventricular relaxation due to concentric remodelling (LVCR, n = 7), and healthy controls (n = 8) underwent CMR at rest and during supine bicycle exercise with simultaneous measurements of central haemodynamics and circulating cGMP levels, before and after oral administration of 50 mg sildenafil. At rest, mean pulmonary artery pressures (mPAP) were higher in HFpEF, compared with LVCR and controls (27 ± 2, 18 ± 1, and 11 ± 1, respectively; P = 0.01), whereas biventricular volumes, heart rate, and stroke volume were similar. During exercise, LVCR and HFpEF had a greater increase in the ratio of mPAP over cardiac output than controls (5.50 ± 0.77 and 6.34 ± 0.86 vs. 2.24 ± 0.55 in controls, P = 0.005). The ratio of peak exercise to rest RV end‐systolic pressure‐volume, a surrogate of RV contractility, was significantly reduced in LVCR and HFpEF (2.32 ± 0.17 and 1.56 ± 0.08 vs. 3.49 ± 0.35 in controls, P < 0.001) and correlated with peak exercise VO₂ (R² = 0.648, P < 0.001). cGMP levels increased with exercise across the HFpEF spectrum (P < 0.05 vs. baseline), except when postcapillary pulmonary hypertension was present at rest (P = 0.73 vs. baseline). A single sildenafil administration failed to increase circulating cGMP levels and did not improve RV performance.

Conclusion

Exercise CMR identifies impaired RV‐arterial coupling at an early stage of HFpEF. Circulating cGMP levels phenocopy the haemodynamic spectrum in HFpEF but fail to increase after phosphodiesterase type 5 inhibition, endorsing the need for alternative interventions to increase cGMP signalling in HFpEF.

Pressure-based estimation of right ventricular ejection fraction: Validation as a clinically relevant target for drug development in a rodent model of pulmonary hypertension

Depressed right ventricular ejection fraction (RVEF) has clear prognostic significance in patients with pulmonary arterial hypertension (PAH). Accordingly, improvements in RVEF represent a desirable end-point in the development of PAH therapies. However, current methods for determination of RVEF require measurement of RV volume and are relatively complex and costly. Here, we validate a novel method for quantitative estimation of RVEF in rats based entirely upon analysis of readily available RV pressure waveforms that eliminates the need for simultaneous volume measurement and can be rapidly applied. Right ventricular pressure and volume (conductance catheter) measurements acquired from 15 rats (7 controls, 8 sugen/hypoxia PAH; 220-250 g) were used for the study. Over the same 10 beat interval, RVEF was directly measured from the volume signal and estimated from the pressure signal. Simultaneous measures were compared by linear regression and Bland-Altman analysis to define bias (accuracy) and precision. Measured RVEF ranged from 0.19 to 0.60 (mean 0.44 ± 0.10) and estimated from 0.19 to 0.52 (mean 0.42 ± 0.09). Across the dataset there was strong correlation (r² = 0.813), with minimal bias (0.01) and an overall error of 20% consistent with acceptable accuracy and precision. Study results support the potential utility of a method based entirely upon analysis of the RV pressure waveform for assessing drug effects on RVEF in rat models of PAH.

Cardiac Magnetic Resonance Imaging in Pulmonary Arterial Hypertension: Ready for Clinical Practice and Guidelines?

Purpose of Review

Pulmonary arterial hypertension (PAH) is a progressive disease with high mortality. A greater understanding of the physiology and function of the cardiovascular system in PAH will help improve survival. This review covers the latest advances within cardiovascular magnetic resonance imaging (CMR) regarding diagnosis, evaluation of treatment, and prognostication of patients with PAH.

Recent Findings

New CMR measures that have been proven relevant in PAH include measures of ventricular and atrial volumes and function, tissue characterization, pulmonary artery velocities, and arterio-ventricular coupling.

Summary

CMR markers carry prognostic information relevant for clinical care such as treatment response and thereby can affect survival. Future research should investigate if CMR, as a non-invasive method, can improve existing measures or even provide new and better measures in the diagnosis, evaluation of treatment, and determination of prognosis of PAH.

Right ventricular pressure-volume loop shape and systolic pressure change in pulmonary hypertension

Right ventricular (RV) function determines outcome in pulmonary arterial hypertension (PAH). RV pressure-volume loops, the gold standard for measuring RV function, are difficult to analyze. Our aim was to investigate whether simple assessments of RV pressure-volume loop morphology and RV systolic pressure differential reflect PAH severity and RV function. We analyzed multibeat RV pressure-volume loops (obtained by conductance catheterization with preload reduction) in 77 patients with PAH and 15 patients without pulmonary hypertension in two centers. Patients were categorized according to their pressure-volume loop shape (triangular, quadratic, trapezoid, or notched). RV systolic pressure differential was defined as end-systolic minus beginning-systolic pressure (ESP - BSP), augmentation index as ESP - BSP/pulse pressure, pulmonary arterial capacitance (PAC) as stroke volume/pulse pressure, and RV-arterial coupling as end-systolic/arterial elastance (Ees/Ea). Trapezoid and notched pressure-volume loops were associated with the highest afterload (Ea), augmentation index, pulmonary vascular resistance (PVR), mean pulmonary arterial pressure, stroke work, B-type natriuretic peptide, and the lowest Ees/Ea and PAC. Multivariate linear regression identified Ea, PVR, and stroke work as the main determinants of ESP - BSP. ESP - BSP also significantly correlated with multibeat Ees/Ea (Spearman's ρ: -0.518, P < 0.001). A separate retrospective analysis of 113 patients with PAH showed that ESP - BSP obtained by routine right heart catheterization significantly correlated with a noninvasive surrogate of RV-arterial coupling (tricuspid annular plane systolic excursion/pulmonary arterial systolic pressure ratio; ρ: -0.376, P < 0.001). In conclusion, pressure-volume loop shape and RV systolic pressure differential predominately depend on afterload and PAH severity and reflect RV-arterial coupling in PAH.

Right ventricular adaptation to pressure-overload: Differences between chronic thromboembolic pulmonary hypertension and idiopathic pulmonary arterial hypertension

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) and idiopathic pulmonary arterial hypertension (iPAH) are both associated with right ventricular (RV) failure and mortality. However, CTEPH patients are older, more often male and usually have more co-morbidities than iPAH patients, including a history of venous thromboembolism. Therefore, RV adaptation to pressure-overload in CTEPH may be different than in iPAH.

METHODS

We included all treatment-naive CTEPH and iPAH patients diagnosed in the Amsterdam UMC between 2000 and 2019 if cardiac magnetic resonance imaging (CMR) and a right heart catheterization were performed at time of diagnosis. Load-dependent RV volumes and mass were assessed with CMR. Load-independent RV contractility, afterload and diastolic stiffness in relation to afterload were obtained using single beat pressure-volume loop analysis. Differences in RV characteristics between CTEPH and iPAH were analyzed using multiple linear regression with interaction testing after correcting for confounders.

RESULTS

We included 235 patients in this study and performed pressure-volume loop analysis in 136 patients. In addition to being older and more often male, CTEPH patients had a lower pulmonary vascular resistance than iPAH patients at the time of diagnosis. After correcting for these confounders, CTEPH patients had a somewhat higher RV end-diastolic volume index (87 ± 27 ml vs 82 ± 25 ml; p < .01), and a lower RV relative wall thickness (0.6 ± 0,1 g/ml vs 0.7 ± 0,2 g/ml; p < .01). The correlation coefficient of RV diastolic stiffness to afterload was higher in CTEPH compared to iPAH (p < .05; independent of age and gender).

CONCLUSIONS

Despite differences in patient characteristics, disease etiology and physiology, RV functional parameters in CTEPH and iPAH are mostly similar. The right ventricle in CTEPH is marginally more dilated, stiffer and less hypertrophic than in iPAH.

A novel non-invasive and echocardiography-derived method for quantification of right ventricular pressure-volume loops

AIMS

We sought to assess the feasibility of constructing right ventricular (RV) pressure-volume (PV) loops solely by echocardiography.

METHODS AND RESULTS

We performed RV conductance and pressure wire (PW) catheterization with simultaneous echocardiography in 35 patients with pulmonary hypertension. To generate echocardiographic PV loops, a reference RV pressure curve was constructed using pooled PW data from the first 20 patients (initial cohort). Individual pressure curves were then generated by adjusting the reference curve according to RV isovolumic and ejection phase duration and estimated RV systolic pressure. The pressure curves were synchronized with echocardiographic volume curves. We validated the reference curve in the remaining 15 patients (validation cohort). Methods were compared with correlation and Bland-Altman analysis. In the initial cohort, echocardiographic and conductance-derived PV loop parameters were significantly correlated {rho = 0.8053 [end-systolic elastance (Ees)], 0.8261 [Ees/arterial elastance (Ea)], and 0.697 (stroke work); all P < 0.001}, with low bias [-0.016 mmHg/mL (Ees), 0.1225 (Ees/Ea), and -39.0 mmHg mL (stroke work)] and acceptable limits of agreement. Echocardiographic and PW-derived Ees were also tightly correlated, with low bias (-0.009 mmHg/mL) and small limits of agreement. Echocardiographic and conductance-derived Ees, Ees/Ea, and stroke work were also tightly correlated in the validation cohort (rho = 0.9014, 0.9812, and 0.9491, respectively; all P < 0.001), with low bias (0.0173 mmHg/mL, 0.0153, and 255.1 mmHg mL, respectively) and acceptable limits.

CONCLUSION

The novel echocardiographic method is an acceptable alternative to invasively measured PV loops to assess contractility, RV-arterial coupling, and RV myocardial work. Further validation is warranted.

Evaluating the Right Ventricle in Acute and Chronic Pulmonary Embolism: Current and Future Considerations

The right ventricle (RV), due to its morphologic and physiologic differences, is susceptible to sudden increase in RV afterload, as noted in patients with acute pulmonary embolism (PE). Functional impairment of RV function is a stronger presage of adverse outcomes in acute PE than the location or burden of emboli. While current iterations of most clinical prognostic scores do not incorporate RV dysfunction, advancements in imaging have enabled more granular and accurate assessment of RV dysfunction in acute PE. RV enlargement and dysfunction on imaging is noted only in a subset of patients with acute PE and is dependent on underlying cardiopulmonary reserve and clot burden. Specific signs like McConnell's and "60/60" sign are noted in less than 20% of patients with acute PE. About 2% of patients with acute PE develop chronic thromboembolic pulmonary hypertension, characterized by continued deterioration in RV function in a subset of patients with a continuum of RV function from preserved to overt right heart failure. Advances in molecular and other imaging will help better characterize RV dysfunction in this population and evaluate the response to therapies.

Right ventriculo-pulmonary arterial uncoupling and poor outcomes in pulmonary arterial hypertension

Right ventricular function critically affects the prognosis of patients with pulmonary arterial hypertension. We aimed to analyze the prognostic value of right ventricular indices calculated using magnetic resonance imaging and right heart catheterization metrics in pulmonary arterial hypertension. We retrospectively collected data from 57 Japanese patients with pulmonary arterial hypertension and 18 controls and calculated six indices of right ventricular function: two indices of contractility (end-systolic elastance calculated with right ventricular maximum pressure and with magnetic resonance imaging metrics); two indices of right ventricular–pulmonary arterial coupling (end-systolic elastance/arterial elastance calculated with the pressure method (end-systolic elastance/arterial elastance (P)) and with the volume method (end-systolic elastance/arterial elastance (V)); and two indices of right ventricular diastolic function (stiffness (β) and end-diastolic elastance). We compared the indices between controls and patients with pulmonary arterial hypertension and examined their prognostic role. In patients with pulmonary arterial hypertension, end-systolic elastance (right ventricular maximum pressure) was higher (pulmonary arterial hypertension 0.94 (median) vs control 0.42 (mmHg/mL), p < 0.001), end-systolic elastance/arterial elastance (V) was lower (pulmonary arterial hypertension 0.72 vs control 1.69, p < 0.001), and β and end-diastolic elastance were significantly higher than those in the controls. According to the log-rank test, end-systolic elastance/arterial elastance (P) and end-diastolic elastance were significantly associated with the composite event rate. According to the multivariate Cox regression analysis, decreased end-systolic elastance/arterial elastance (P) was associated with a higher composite event rate (hazard ratio 11.510, 95% confidence interval: 1.954–67.808). In conclusion, an increased right ventricular contractility, diastolic dysfunction, and a trend of impaired right ventricular–pulmonary arterial coupling were observed in our pulmonary arterial hypertension cohort. According to the multivariate outcome analysis, a decreased end-systolic elastance/arterial elastance (P), suggestive of impaired right ventricular–pulmonary arterial coupling, best predicted the pulmonary arterial hypertension-related event.