Upfront combination therapy reduces right ventricular volumes in pulmonary arterial hypertension

Insights Into Differences in Pulmonary Hemodynamics in Hispanic Patients With Pulmonary Arterial Hypertension

Background

Emerging data suggest that Hispanic patients with pulmonary arterial hypertension (PAH) exhibit improved survival rates compared to individuals of other ethnicities with similar baseline hemodynamics. However, the underlying reasons for this survival advantage remain unclear. This study focused on comparing pulmonary hemodynamics in Hispanic and non-Hispanic PAH patients and how these differences may contribute to varied clinical outcomes.

Methods

A retrospective analysis of right heart catheterization data was conducted on a treatment-naive PAH patient cohort from a single center.

Results

Over a 10-year period, a total of 226 PAH patients were identified, of which 138 (61%) were Hispanic and 88 (39%) were non-Hispanic. Hispanic patients presented with lower pulmonary artery pressures, lower pulmonary vascular resistance, and exhibited significantly higher pulmonary arterial compliance (PAc). Hispanic patients had better 5-year survival rates.

Conclusions

This study highlights the importance of exploring phenotypic differences in ethnically diverse PAH cohorts.

State-of-the Art Cardiac Magnetic Resonance in Pulmonary Hypertension - An Update on Diagnosis, Risk Stratification and Treatment

Pulmonary hypertension (PH) is a globally under-recognized but life-shortening disease with a poor prognosis if untreated, delayed or inappropriately treated. One of the most important issues for PH is to improve patient quality of life and survival through timely and accurate diagnosis, precise risk stratification and prognosis prediction. Cardiac magnetic resonance (CMR), a non-radioactive, non-invasive image-based examination with excellent tissue characterization, provides a comprehensive assessment of not only the disease severity but also secondary changes in cardiac structure, function and tissue characteristics. The purpose of this review is to illustrate an updated status of CMR for PH assessment, focusing on the application of both conventional and emerging technologies as well as the latest clinical trials.

Comparison of cardiac magnetic resonance imaging, functional and haemodynamic variables in pulmonary arterial hypertension: insights from REPAIR

Background

Measures that can detect large treatment effects are important for monitoring therapeutic effectiveness. The 2022 European Society of Cardiology/European Respiratory Society guidelines highlight the importance of imaging in monitoring disease status and treatment response in pulmonary arterial hypertension (PAH). Are the standardised treatment effect sizes (STES) of cardiac magnetic resonance imaging (cMRI) comparable with functional and haemodynamic variables?

Methods

REPAIR (ClinicalTrials.gov: NCT02310672) was a prospective, multicentre, single-arm, open-label, 52-week phase 4 study evaluating the effect of macitentan 10 mg, with or without a phosphodiesterase 5 inhibitor (PDE5i), on right ventricular (RV) remodelling, cardiac function and cardiopulmonary haemodynamics. Both cMRI and functional assessments were performed at screening and at weeks 26 and 52; haemodynamic measurements were conducted at screening and week 26. In this post hoc analysis, STES were estimated using the parametric Cohen's d and non-parametric Cliff's delta tests.

Results

At week 26, large STES (Cohen's d) were observed for 10 of the 20 cMRI variables assessed, including the prognostic measures of RV and left ventricular stroke volume and RV ejection fraction and the haemodynamic trial end-point, pulmonary vascular resistance; medium STES were observed for 6-min walk distance (6MWD). The STES were consistent in treatment-naïve patients and those escalating therapy and maintained at week 52. Similar results were obtained using the non-parametric Cliff's delta method.

Conclusions

The treatment effect of macitentan, alone or in combination with a PDE5i, was comparable for several cMRI and haemodynamic variables with prognostic value in PAH, and greater than that of 6MWD in patients with PAH, highlighting the emerging relevance of cMRI in PAH.

Contribution of pressure and flow changes to resistance reduction after pulmonary arterial hypertension treatment: a meta-analysis of 3898 patients

Background

Pulmonary arterial hypertension (PAH)-targeted therapies exert significant haemodynamic changes; however, systematic synthesis is currently lacking.

Methods

We searched PubMed, CENTRAL and Web of Science for studies evaluating mean pulmonary artery pressure (mPAP), cardiac index/cardiac output (CI/CO) and pulmonary vascular resistance (PVR) of PAH-targeted therapies either in monotherapy or combinations as assessed by right heart catheterisation in treatment-naïve PAH patients. We performed a random-effects meta-analysis with meta-regression.

Results

We included 68 studies (90 treatment groups) with 3898 patients (age 47.4±13.2 years, 74% women). In studies with small PVR reduction (<4 WU), CI/CO increase (R2=62%) and not mPAP reduction (R2=24%) was decisive for the PVR reduction (p<0.001 and p=0.36, respectively, in the multivariable meta-regression model); however, in studies with large PVR reduction (>4 WU), both CI/CO increase (R2=72%) and mPAP reduction (R2=35%) contributed significantly to the PVR reduction (p<0.001 and p=0.01, respectively). PVR reduction as a percentage of the pre-treatment value was more pronounced in the oral+prostanoid intravenous/subcutaneous combination therapy (mean difference -50.0%, 95% CI -60.8- -39.2%), compared to oral combination therapy (-41.7%, -47.6- -35.8%), prostanoid i.v./s.c. monotherapy (-31.8%, -37.6- -25.9%) and oral monotherapy (-21.6%, -25.4- -17.8%). Changes in haemodynamic parameters were significantly associated with changes in functional capacity of patients with PAH as expressed by the 6-min walking distance.

Conclusion

Combination therapies, especially with the inclusion of parenteral prostanoids, lead to remarkable haemodynamic improvement in treatment-naïve PAH patients and may unmask the contribution of mPAP reduction to the overall PVR reduction in addition to the increase in CO.

Right ventricular to pulmonary arterial coupling in patients with repaired tetralogy of Fallot: a case series

Background

In repaired tetralogy of Fallot (ToF) patients with residual right ventricular (RV) outflow tract obstructions (RVOTO), risk stratification and timing of re-interventions are based on RVOTO gradients. However, this might be insufficient to prevent RV dysfunction. Instead, assessment of RV to pulmonary arterial (RV-PA) coupling allows integrated assessment of RV function in relationship to its afterload and could be of additional value in clinical decision-making.

Case summary

Two patients with repaired ToF and residual RVOTO without pulmonary regurgitation underwent right heart catheterization (RHC) and cardiac magnetic resonance imaging. We determined RV end-systolic elastance (Ees), arterial elastance (Ea) and RV-PA coupling (Ees/Ea) using single-beat RV pressure-volume analysis. Patient 1 was asymptomatic despite severely increased RV pressures and a left pulmonary artery (LPA) stenosis (invasive gradient 20 mmHg). Right ventricular volumes and function were preserved. The Ea and Ees were increased but RV-PA coupling was relatively maintained. Of interest, RV end-diastolic pressure and RV diastolic stiffness were increased. After LPA plasty, RV function was preserved during long-term follow-up. Patient 2 was symptomatic despite mildly elevated RV pressures and a supravalvular RV-PA conduit stenosis (invasive gradient 30 mmHg). The RV showed severe RV dilatation and dysfunction. The Ea was increased but Ees was decreased leading to RV-PA uncoupling. Despite balloon angioplasty, RV function was unchanged during long-term follow-up.

Discussion

Development of RV dysfunction might be insufficiently predicted by RVOTO severity in patients with repaired ToF. Assessment of RV remodelling and function in relationship to its afterload might help to optimize risk stratification.

Management of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare pulmonary vascular disease characterized by progressive pulmonary arterial remodeling, increased pulmonary vascular resistance, right ventricular dysfunction, and reduced survival. Effective therapies have been developed that target three pathobiologic pathways in PAH: nitric oxide, endothelin-1, and prostacyclin. Approved therapies for PAH include phosphodiesterase type-5 inhibitors, soluble guanylate cyclase stimulators, endothelin receptor antagonists, prostacyclin analogs, and prostacyclin receptor agonists. Management of PAH in the modern era incorporates multidimensional risk assessment to guide the use of these medications. For patients with PAH and without significant comorbidities, current guidelines recommend two oral medications (phosphodiesterase type-5 inhibitor and endothelin receptor antagonist) for low- and intermediate-risk patients, with triple therapy including a parenteral prostacyclin to be considered in those at high or intermediate-high risk. Combination therapy may be poorly tolerated and less effective in patients with PAH and cardiopulmonary comorbidities. Thus, a single-agent approach with individualized decisions to add-on other PAH therapies is recommended in older patients and those with significant comorbid conditions. Management of PAH is best performed in multidisciplinary teams located in experienced centers. Other core pillars of PAH management include supportive and adjunctive treatments including oxygen, diuretics, rehabilitation, and anticoagulation in certain patients. Patients with PAH who progress despite optimal treatment or who are refractory to best medical care should be referred for lung transplantation, if eligible. Despite considerable progress, PAH is often fatal and new therapies that reverse the disease and improve outcomes are desperately needed.

Restoration of right ventricular function in the treatment of pulmonary arterial hypertension

OBJECTIVE

A 45% threshold of right ventricular ejection fraction (RVEF) is proposed clinically relevant in patients with pulmonary arterial hypertension (PAH). We aim to determine treatment response, long-term right ventricular (RV) functional stability and prognosis of patients with PAH reaching or maintaining the RVEF 45% threshold.

METHODS

Incident, treatment-naive, adult PAH patients with cardiac magnetic resonance imaging at baseline and first follow-up were included (total N=127) and followed until date of censoring or death/lung transplantation. Patients were categorised into two groups based on 45% RVEF. Baseline predictors, treatment response and prognosis were assessed with logistic regression analyses, two-way analysis of variance and log-rank tests.

RESULTS

Patients were 50±17 years old, 73% female, of which N=75 reached or maintained the 45% RVEF threshold at follow-up (RVEF≥45%@FU), while N=52 patients did not (RVEF<45%@FU). RV end-diastolic volume and N-terminal pro-B-type natriuretic peptide at baseline were multivariable predictors of an RVEF ≥45% at follow-up. A 40% pulmonary vascular resistance (PVR) reduction resulted in greater improvement in RV function (ΔRVEF 17±11 vs. 5±8; pinteraction<0.001) compared to a PVR reduction <40%, but did not guarantee an RVEF ≥45%. Finally, the 45% RVEF threshold was associated with stable RV function during long-term follow-up and better survival (HR: 1.91 (95% CI: 1.11 to 3.27)). Patients failing to reach or maintain the 45% RVEF threshold at first follow-up mostly stayed below this threshold over the next consecutive visits.

CONCLUSION

After treatment initiation, 60% of patients with PAH reach or maintain the 45% RVEF threshold, which is associated with a long-term stable RV function and favourable prognosis.

Classification and Predictors of Right Ventricular Functional Recovery in Pulmonary Arterial Hypertension

BACKGROUND

Normative changes in right ventricular (RV) structure and function have not been characterized in the context of treatment-associated functional recovery (RV functional recovery [RVFnRec]). The aim of this study is to assess the clinical relevance of a proposed RVFnRec definition.

METHODS

We evaluated 63 incident patients with pulmonary arterial hypertension by right heart catheterization and cardiac magnetic resonance imaging at diagnosis and cardiac magnetic resonance imaging and invasive cardiopulmonary exercise testing following treatment (≈11 months). Sex, age, ethnicity matched healthy control subjects (n=62) with 1-time cardiac magnetic resonance imaging and noninvasive cardiopulmonary exercise testing were recruited from the PVDOMICS (Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics) project. We examined therapeutic cardiac magnetic resonance imaging changes relative to the evidence-based peak oxygen consumption (VO2peak)>15 mL/(kg·min) to define RVFnRec by receiver operating curve analysis. Afterload was measured as mean pulmonary artery pressure, resistance, compliance, and elastance.

RESULTS

A drop in RV end-diastolic volume of -15 mL best defined RVFnRec (area under the curve, 0.87; P=0.0001) and neared upper 95% CI RV end-diastolic volume of controls. This cutoff was met by 22 out of 63 (35%) patients which was reinforced by freedom from clinical worsening, RVFnRec 1 out of 21 (5%) versus no RVFnRec 17 out of 42, 40% (log-rank P=0.006). A therapy-associated increase of 0.8 mL/mm Hg in compliance had the best predictive value of RVFnRec (area under the curve, 0.76; [95% CI, 0.64-0.88]; P=0.001). RVFnRec patients had greater increases in stroke volume, and cardiac output at exercise.

CONCLUSIONS

RVFnRec defined by RV end-diastolic volume therapeutic decrease of -15 mL predicts exercise capacity, freedom from clinical worsening, and nears normalization. A therapeutic improvement of compliance is superior to other measures of afterload in predicting RVFnRec. RVFnRec is also associated with increased RV output reserve at exercise.

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.

Establishing minimally important differences for cardiac MRI end-points in pulmonary arterial hypertension

BACKGROUND

Cardiac magnetic resonance (CMR) is the gold standard technique to assess biventricular volumes and function, and is increasingly being considered as an end-point in clinical studies. Currently, with the exception of right ventricular (RV) stroke volume and RV end-diastolic volume, there is only limited data on minimally important differences (MIDs) reported for CMR metrics. Our study aimed to identify MIDs for CMR metrics based on US Food and Drug Administration recommendations for a clinical outcome measure that should reflect how a patient "feels, functions or survives".

METHODS

Consecutive treatment-naïve patients with pulmonary arterial hypertension (PAH) between 2010 and 2022 who had two CMR scans (at baseline prior to treatment and 12 months following treatment) were identified from the ASPIRE registry. All patients were followed up for 1 additional year after the second scan. For both scans, cardiac measurements were obtained from a validated fully automated segmentation tool. The MID in CMR metrics was determined using two distribution-based (0.5sd and minimal detectable change) and two anchor-based (change difference and generalised linear model regression) methods benchmarked to how a patient "feels" (emPHasis-10 quality of life questionnaire), "functions" (incremental shuttle walk test) or "survives" for 1-year mortality to changes in CMR measurements.

RESULTS

254 patients with PAH were included (mean±sd age 53±16 years, 79% female and 66% categorised as intermediate risk based on the 2022 European Society of Cardiology/European Respiratory Society risk score). We identified a 5% absolute increase in RV ejection fraction and a 17 mL decrease in RV end-diastolic or end-systolic volumes as the MIDs for improvement. Conversely, a 5% decrease in RV ejection fraction and a 10 mL increase in RV volumes were associated with worsening.

CONCLUSIONS

This study establishes clinically relevant CMR MIDs for how a patient "feels, functions or survives" in response to PAH treatment. These findings provide further support for the use of CMR as a clinically relevant clinical outcome measure and will aid trial size calculations for studies using CMR.

Should We Change the Target of Therapy in Pulmonary Hypertension?

Despite the evolution of drug therapy in pulmonary arterial hypertension and the more aggressive treatment approach according to the guidelines, patients continue to have unacceptable mortality rates. Furthermore, specific drug therapy alone in chronic thromboembolic pulmonary hypertension also does not seem to have any beneficial impact on survival. As the function of the right ventricle (RV) determines the prognosis of patients with pulmonary hypertension, the treatment strategy should focus on modifying factors involved in RV dysfunction. Although some previous reports demonstrated that the survival of patients with pulmonary hypertension was associated with mPAP, nevertheless, mPAP is still not considered as a target of therapy. There are many examples of effective mPAP lowering with early and aggressive drug therapy in pulmonary arterial hypertension, or with interventions in chronic thromboembolic pulmonary hypertension. This effective mPAP reduction can lead to reverse RV remodeling, and thus, improvement in survival. In this article, the importance of mPAP lowering is stated, as well as why the change of our current strategy and considering mPAP reduction as the target of therapy could make pulmonary hypertension a chronic but not fatal disease.

Classification and Predictors of Right Ventricular Functional Recovery in Pulmonary Arterial Hypertension

Background

Normative changes in right ventricular (RV) structure and function have not been characterized in the context of treatment-associated functional recovery (RVFnRec). The aim of this study is to assess the clinical relevance of a proposed RVFnRec definition.

Methods

We evaluated 63 incident patients with PAH by right heart catheterization and cardiac MRI (CMR) at diagnosis and CMR and invasive cardiopulmonary exercise (CPET) following treatment (∼11 months). Sex, age, race/ethnicity matched healthy control subjects (n=62) with one-time CMR and non-invasive CPET were recruited from the PVDOMICS project. We examined therapeutic CMR changes relative to the evidence-based peak oxygen consumption (VO2 peak )>15mL/kg/min to define RVFnRec by receiver operating curve analysis. Afterload was measured in the as mean pulmonary artery pressure, resistance, compliance, and elastance.

Results

A drop in RV end-diastolic volume of -15 mL best defined RVFnRec (AUC 0.87, P=0.0001) and neared upper 95% CI RVEDV of controls. 22/63 (35%) of subjects met this cutoff which was reinforced by freedom from clinical worsening, RVFnRec 1/21 (5%) versus no RVFnRec 17/42, 40%, (log rank P=0.006). A therapy-associated increase of 0.8 mL/mmHg in compliance had the best predictive value of RVFnRec (AUC 0.76, CI 0.64-0.88, P=0.001). RVFnRec subjects had greater increases in stroke volume, and cardiac output at exercise.

Conclusions

RVFnRec defined by RVEDV therapeutic decrease of -15mL predicts exercise capacity, freedom from clinical worsening, and nears normalization. A therapeutic improvement of compliance is superior to other measures of afterload in predicting RVFnRec. RVFnRec is also associated with increased RV output reserve at exercise.

Clinical Perspective

What is new?: Right ventricular functional recovery (RVFnRec) represents a novel endpoint of therapeutic success in PAH. We define RVFnRec as treatment associated normative RV changes related to function (peak oxygen consumption). Normative RV imaging changes are compared to a well phenotyped age, sex, and race/ethnicity matched healthy control cohort from the PVDOMICS project. Previous studies have focused on RV ejection fraction improvements. However, we show that changes in RVEDV are perhaps more important in that improvements in LV function also occur. Lastly, RVFnRec is best predicted by improvements in pulmonary artery compliance versus pulmonary vascular resistance, a more often cited metric of RV afterload.What are the clinical implications?: RVFnRec represents a potential non-invasive assessment of clinical improvement and therapeutic response. Clinicians with access to cardiac MRI can obtain a limited scan (i.e., ventricular volumes) before and after treatment. Future study should examine echocardiographic correlates of RVFnRec.

Early echocardiographic evaluation of right ventricular load adaptability after sequential combination treatment in pulmonary arterial hypertension

BACKGROUND

Using the tricuspid annular plane systolic excursion (TAPSE)/pulmonary arterial systolic pressure (PASP) ratio as an index of right ventricular load adaptability, we aimed to evaluate early changes in right heart contractile function of patients with group 1 pulmonary artery hypertension (PAH) after sequential combination PAH-specific therapy.

METHODS

A total of 49 patients with group 1 PAH and 31 control participants were included in the study. The baseline clinical and echocardiographic data of the control and PAH group were compared. Subsequently, clinical and echocardiographic data of PAH patients before treatment and at 6 months after PAH-specific treatment were analyzed.

RESULTS

A significant increase in the TAPSE/PASP ratio was found in patients at 6 months of PAH-specific treatment (0.25 ± 0.14; 0.33 ± 0.16, p < 0.001). Right atrial pressure (8 mm Hg [5-10]; 5 mm Hg [3-8], p < 0.001) and PASP (80.8 ± 30.6 mm Hg; 65.9 ± 25.7 mm Hg, p < 0.001) were significantly lower after sequential combination PAH-specific therapy. Negative correlations were found between the TAPSE/PASP ratio and N‑terminal pro-B-type natriuretic peptide (r = -0.524, p < 0.001), tricuspid regurgitation velocity (r = -0.749, p < 0.001), right atrial area (r = -0.298, p = 0.037), and right atrial pressure (r = -0.463, p = 0.001).

CONCLUSION

In patients with group 1 PAH, echocardiographic evaluation at the early stage of treatment (6 months) shows a significant improvement in the TAPSE/PASP ratio indicating right ventricular load adaptation. Comprehensive studies are needed on the routine use of the TAPSE/PASP ratio in the risk assessment of PAH patients.

Exploring the failing right ventricle in pulmonary hypertension by CMR: An in vivo study utilising Macitentan

Cardiac magnetic resonance (CMR) imaging is used to assess the right ventricle (RV) of pulmonary hypertensive (PH) patients and more recently to track changes in response to therapy. We wished to investigate if repeat CMRs could be used to assess ventricular changes in the Sugen 5416 hypoxic (Su/Hx) rat model of PH treated with the dual endothelin receptor antagonist Macitentan. Male Sprague Dawley Su/Hx rats were dosed for 3 weeks with either vehicle or Macitentan (30 mg/kg) daily, control rats received only vehicle. All rats underwent three CMR scans; before treatment, 2 weeks into treatment, and end of the study. A separate group of Su/Hx and control rats, treated as above, underwent terminal hemodynamic measurements. Using terminal and CMR measurements, Macitentan was found to lower RV systolic pressure pulmonary artery remodeling and increase RV ejection fraction but not change RV hypertrophy (RVH). Repeat CMRs determined that Su/Hx rats treated with Macitentan had significantly reversed RVH via reducing RV mass as well as reducing elevated left ventricular eccentricity index; reductions in RV mass were also observed in Su/Hx vehicle rats exposed to normoxic conditions. We have demonstrated that repeat CMRs can be used to assess the volume and structural changes in the ventricles of the Su/Hx rat model. Using repeat CMRs has allowed us to build a more complete picture of the response of the RV and the left ventricle to treatment. It is unknown if these effects are a consequence of direct action on the RV or secondary to improvements in the lung vasculature.

Echocardiographic Evaluation of Initial Ambrisentan Plus Phosphodiesterase Type 5 Inhibitor on Right Ventricular Pulmonary Artery Coupling in Severe Pulmonary Arterial Hypertension Patients

Introduction

ambrisentan and phosphodiesterase type 5 inhibitor (PDE5i) have been approved for treating patients with pulmonary arterial hypertension (PAH). Echocardiographic right ventricular pulmonary artery coupling (RVPAC) has been shown to be a valid non-invasive and alternative measurement method to assess the predicted outcomes in PAH patients. The aim of this study was to study the effect and clinical correlates of initial ambrisentan plus PDE5i combination therapy on RVPAC in patients with severe PAH.

Method and Results

We retrospectively studied and analyzed comprehensive clinical data, hemodynamics, and echocardiography in 27 patients with severe PAH before and after 6 months of initial combination therapy. Compared with the baseline, significant improvements in RVPAC ratios were observed, including RVFAC/PASP (0.31 ± 0.10 vs. 0.44 ± 0.15%/mmHg, p &lt; 0.001), TAPSE/PASP (0.15 ± 0.05 vs. 0.21 ± 0.06 mm/mmHg, p = 0.001), S’/PASP (0.10 ± 0.03 vs. 0.14 ± 0.05 cm/s∙mmHg, p = 0.001), and RVSV/RVESV (0.79 ± 0.22 vs. 1.02 ± 0.20, p &lt; 0.001). Functional status indices [World Health Organization functional classifications (WHO-FC) and 6 min walk distance (6MWD) and N-terminal pro B-type natriuretic peptide (NT-proBNP) levels] showed significant improvements. Right heart catheterization (RHC) evaluations for hemodynamic measurements between baseline and the 6–12 month follow-up were sPAP (96 ± 22 vs. 86 ± 24 mmHg, p = 0.002), mPAP (64 ± 18 vs. 56 ± 17 mmHg, p &lt; 0.001) and TPVR (17.3 ± 6.7 vs. 12.1 ± 5.4 WU, p = 0.001). Simultaneously, significant associations between RVPAC ratios and NT-proBNP levels and WHO-FC and 6MWD were observed.

Conclusion

Ambrisentan plus PDE-5i combination therapy resulted in a significant improvement in RVPAC in severe PAH. Importantly, RVPAC parameters correlated with known prognostic markers of PAH.

When right ventricular pressure meets volume: the impact of arrival time of reflected waves on right ventricle load in pulmonary arterial hypertension

Abstract

Right ventricular (RV) wall tension in pulmonary arterial hypertension (PAH) is determined not only by pressure, but also by RV volume. A larger volume at a given pressure generates more wall tension. Return of reflected waves early after the onset of contraction, when RV volume is larger, may augment RV load. We aimed to elucidate: (1) the distribution of arrival times of peak reflected waves in treatment‐naïve PAH patients; (2) the relationship between time of arrival of reflected waves and RV morphology; and (3) the effect of PAH treatment on the arrival time of reflected waves. Wave separation analysis was conducted in 68 treatment‐naïve PAH patients. In the treatment‐naïve condition, 54% of patients had mid‐systolic return of reflected waves (defined as 34–66% of systole). Despite similar pulmonary vascular resistance (PVR), patients with mid‐systolic return had more pronounced RV hypertrophy compared to those with late‐systolic or diastolic return (RV mass/body surface area; mid‐systolic return 54.6 ± 12.6 g m^–2, late‐systolic return 44.4 ± 10.1 g m^–2, diastolic return 42.8 ± 13.1 g m^–2). Out of 68 patients, 43 patients were further examined after initial treatment. At follow‐up, the stiffness of the proximal arteries, given as characteristic impedance, decreased from 0.12 to 0.08 mmHg s mL^–1. Wave speed was attenuated from 13.3 to 9.1 m s^–1, and the return of reflected waves was delayed from 64% to 71% of systole. In conclusion, reflected waves arrive at variable times in PAH. Early return of reflected waves was associated with more RV hypertrophy. PAH treatment not only decreased PVR, but also delayed the timing of reflected waves.

Key points

Right ventricular (RV) wall tension in pulmonary arterial hypertension (PAH) is determined not only by pressure, but also by RV volume. Larger volume at a given pressure causes larger RV wall tension.

Early return of reflected waves adds RV pressure in early systole, when RV volume is relatively large. Thus, early return of reflected waves may increase RV wall tension. Wave reflection can provide a description of RV load.

In PAH, reflected waves arrive back at variable times. In over half of PAH patients, the RV is exposed to mid‐systolic return of reflected waves. Mid‐systolic return of reflected waves is related to RV hypertrophy.

PAH treatment acts favourably on the RV not only by reducing resistance, but also by delaying the return of reflected waves.

Arrival timing of reflected waves is an important parameter for understanding the relationship between RV load and its function in PAH.

Aggressive Afterload Lowering to Improve the Right Ventricle: A New Target for Medical Therapy in Pulmonary Arterial Hypertension?

Despite numerous therapeutic advances in pulmonary arterial hypertension, patients continue to suffer high morbidity and mortality, particularly considering a median age of 50 years. This article explores whether early, robust reduction of right ventricular afterload would facilitate substantial improvement in right ventricular function and thus whether afterload reduction should be a treatment goal for pulmonary arterial hypertension. The earliest clinical studies of prostanoid treatment in pulmonary arterial hypertension demonstrated an important link between lowering mean pulmonary arterial pressure (or pulmonary vascular resistance) and improved survival. Subsequent studies of oral monotherapy or sequential combination therapy demonstrated smaller reductions in mean pulmonary arterial pressure and pulmonary vascular resistance. More recently, retrospective reports of initial aggressive prostanoid treatment or initial combination oral and parenteral therapy have shown marked afterload reduction along with significant improvements in right ventricular function. Some data suggest that reaching threshold levels for pressure or resistance (components of right ventricular afterload) may be key to interrupting the self-perpetuating injury of pulmonary vascular disease in pulmonary arterial hypertension and could translate into improved long-term clinical outcomes. Based on these clues, the authors postulate that improved clinical outcomes might be achieved by targeting significant afterload reduction with initial oral combination therapy and early parenteral prostanoids.

Mineralocorticoid receptor antagonist treatment of established pulmonary arterial hypertension improves interventricular dependence in the SU5416-hypoxia rat model

Treatment with mineralocorticoid receptor (MR) antagonists beginning at the outset of disease, or early thereafter, prevents pulmonary vascular remodeling in preclinical models of pulmonary arterial hypertension (PAH). However, the efficacy of MR blockade in established disease, a more clinically relevant condition, remains unknown. Therefore, we investigated the effectiveness of two MR antagonists, eplerenone (EPL) and spironolactone (SPL), after the development of severe right ventricular (RV) dysfunction in the rat SU5416-hypoxia (SuHx) PAH model. Cardiac magnetic resonance imaging (MRI) in SuHx rats at the end of week 5, before study treatment, confirmed features of established disease including reduced RV ejection fraction and RV hypertrophy, pronounced septal flattening with impaired left ventricular filling and reduced cardiac index. Five weeks of treatment with either EPL or SPL improved left ventricular filling and prevented the further decline in cardiac index compared with placebo. Interventricular septal displacement was reduced by EPL whereas SPL effects were similar, but not significant. Although MR antagonists did not significantly reduce pulmonary artery pressure or vessel remodeling in SuHx rats with established disease, animals with higher drug levels had lower pulmonary pressures. Consistent with effects on cardiac function, EPL treatment tended to suppress MR and proinflammatory gene induction in the RV. In conclusion, MR antagonist treatment led to modest, but consistent beneficial effects on interventricular dependence after the onset of significant RV dysfunction in the SuHx PAH model. These results suggest that measures of RV structure and/or function may be useful endpoints in clinical trials of MR antagonists in patients with PAH.

Safety and tolerability of combination therapy with ambrisentan and tadalafil for the treatment of pulmonary arterial hypertension in children: Real-world experience

OBJECTIVE

To describe the safety and tolerability of treatment with ambrisentan and tadalafil in pediatric pulmonary hypertension (PH).

STUDY DESIGN

This retrospective observational two-center study included subjects (≤18 years of age) with PH receiving combination therapy with ambrisentan and tadalafil. Before initiating this therapy, many patients were on other therapies for PH. At baseline, patients either received no therapy or monotherapy with a phosphodiesterase 5 inhibitor (PDE5i) or endothelin receptor antagonist (ERA) (Group A), switched from a different PDE5i and ERA (Group B), or were on prostanoid therapy with or without a PDE5i and/or ERA (Group C and D). Demographics, symptoms, and adverse effects were collected. Pre- and postvalues for exercise capacity, hemodynamics, and biomarkers were compared.

RESULTS

There were 43 subjects (26 F, 17 M) ages 4-17.5 years (median 9.3) with World Symposium of PH group 1, 3, and 5. Significant improvements were seen in change scores at follow-up in the entire sample and Group A for 6-min walk distance: +37.0 (6.5-71.0) [p = 0.022], mean pulmonary artery pressure: -6.0 (-14.0 to -3.5) [p = .002], pulmonary vascular resistance: -1.7 (-6.2 to -1.0) [p = .003], NT-proBNP -32.9 (-148.9 to -6.7) [p = .025]. WHO functional class improved in 39.5% and was unchanged in 53.5%; PH risk scores improved in 16%; were unchanged in 56%; and declined in 14%. Three patients discontinued therapy (two headaches, one peripheral edema). Seven patients were hospitalized for worsening disease (2/7 had a Potts shunt placed, 2/7 had an atrial septostomy). There were no deaths or lung transplantation.

CONCLUSIONS

Combination therapy with ambrisentan and tadalafil was well-tolerated, with an acceptable safety profile in a select group of children. This therapy was associated with improved exercise capacity and hemodynamics in children who were treatment naïve or on monotherapy with a PH medication before the initiation of ambrisentan and tadalafil. Based on these early data, further study of combination therapy in pediatric PH is warranted.

The REPAIR Study: Effects of Macitentan on RV Structure and Function in Pulmonary Arterial Hypertension

OBJECTIVES

The REPAIR (Right vEntricular remodeling in Pulmonary ArterIal hypeRtension) study evaluated the effect of macitentan on right ventricular (RV) and hemodynamic outcomes in patients with pulmonary arterial hypertension (PAH), using cardiac magnetic resonance (CMR) and right heart catheterization (RHC).

BACKGROUND

RV failure is the primary cause of death in PAH. CMR is regarded as the most accurate noninvasive method for assessing RV function and remodeling and CMR measures of RV function and structure are strongly prognostic for survival in patients with PAH. Despite this, CMR is not routinely used in PAH clinical trials.

METHODS

REPAIR was a 52-week, open-label, single-arm, multicenter, phase 4 study evaluating the effect of macitentan 10 mg, with or without phosphodiesterase type-5 inhibition, on RV remodeling and function and cardiopulmonary hemodynamics. Primary endpoints were change from baseline to week 26 in RV stroke volume, determined by CMR; and pulmonary vascular resistance, determined by RHC. Efficacy measures were assessed for all patients with baseline and week 26 data for both primary endpoints.

RESULTS

At a prespecified interim analysis in 42 patients, both primary endpoints were met, enrollment was stopped, and the study was declared positive. At final analysis (n = 71), RV stroke volume increased by 12 mL (96% confidence level: 8.4-15.6 mL; P < 0.0001) and pulmonary vascular resistance decreased by 38% (99% confidence level: 31%-44%; P < 0.0001) at week 26. Significant positive changes were also observed in secondary and exploratory CMR (RV and left ventricular), hemodynamic, and functional endpoints at week 26. Improvements in CMR RV and left ventricular variables and functional parameters were maintained at week 52. Safety (n = 87) was consistent with previous clinical trials.

CONCLUSIONS

In the context of this study, macitentan treatment in patients with PAH resulted in significant and clinically-relevant improvements in RV function and structure and cardiopulmonary hemodynamics. At 52 weeks, improvements in RV function and structure were sustained. (REPAIR: Right vEntricular remodeling in Pulmonary ArterIal hypeRtension [REPAIR]; NCT02310672).

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.

The Right Ventricular-Pulmonary Arterial Coupling and Diastolic Function Response to Therapy in Pulmonary Arterial Hypertension

BACKGROUND

Multiparametric risk assessment is used in pulmonary arterial hypertension (PAH) to target therapy. However, this strategy is imperfect as most patients remain in intermediate or high risk after initial treatment with low risk being the goal. Metrics of right ventricular (RV) adaptation are promising tools that may help refine our therapeutic strategy.

RESEARCH QUESTION

Does RV adaptation predict therapeutic response over time?

STUDY DESIGN AND METHODS

We evaluated 52 incident treatment naïve patients with advanced PAH by catheterization and cardiac imaging longitudinally at baseline, follow-up 1 (∼3 mo.) and follow-up 2 (∼18 mo.). All patients were placed on goal-directed therapy with parenteral treprostinil and/or combination therapy with treatment escalation if functional class I-II was not achieved. Therapeutic response was evaluated at follow-up 1 as non-responders (died) or responders and again at follow-up 2 as super-responders (low risk) or partial-responders (high/intermediate risk). Multiparametric risk was based on a simplified ERS/ESC guideline score. RV adaptation was evaluated with the single-beat coupling ratio (Ees/Ea) and diastolic function with diastolic elastance (Eed). Data are expressed as mean±SD or odds ratio [95%CI].

RESULTS

Nine patients (17%) were non-responders. PAH-directed therapy improved ERS low risk from 1 (2%) at baseline to 23 (55%) at follow-up 2. Ees/Ea at presentation was non-significantly higher in responders (0.9±0.4) versus non-responders (0.6±0.4, p=0.09) but was unable to predict super-responder status at follow-up 2 (odds ratio 1.40 [0.28-7.0], p=0.84). Baseline RVEF and change in Eed successfully predicted super-responder status at follow-up 2 (odds ratio 1.15 [1.0-1.27], p=0.009 and 0.29 [0.86-0.96], p=0.04, respectively).

INTERPRETATION

In patients with advanced PAH, RV-PA coupling could not discriminate irreversible RV failure (non-responders) at presentation but showed a late trend to improvement by follow-up 2. Early change in Eed and baseline RVEF were the best predictors of therapeutic response.

Advances in the management of pulmonary arterial hypertension

The management of pulmonary arterial hypertension (PAH) has significantly evolved over the last decades in the wake of more sensitive diagnostics and specialized clinical programs that can provide focused medical care. In the current era of PAH care, 1-year survival rates have increased to 86%–90% from 65% in the 1980s, and average long-term survival has increased to 6 years from 2.8 years. The heterogeneity in the etiology and disease course has opened doors to focusing research in phenotyping the disease and understanding the pathophysiology at a cellular and genetic level. This may eventually lead to precision medicine and the development of medications that may prevent or reverse pulmonary vascular remodeling. With more insight, clinical trial designs and primary end-points may change to identify the true survival benefit of pharmacotherapy. Identifying responders from non-responders to therapy may help provide individualized patient-centered care rather than an algorithm-based approach. The purpose of this review is to highlight the latest advances in screening, diagnosis, and management of PAH.

Application of [18F]FLT-PET in pulmonary arterial hypertension: a clinical study in pulmonary arterial hypertension patients and unaffected bone morphogenetic protein receptor type 2 mutation carriers

Pulmonary arterial hypertension is a heterogeneous group of diseases characterized by vascular cell proliferation leading to pulmonary vascular remodelling and ultimately right heart failure. Previous data indicated that 3′-deoxy-3′-[18F]-fluorothymidine (¹⁸FLT) positron emission tomography (PET) scanning was increased in pulmonary arterial hypertension patients, hence providing a possible biomarker for pulmonary arterial hypertension as it reflects vascular cell hyperproliferation in the lung. This study sought to validate ¹⁸FLT-PET in an expanded cohort of pulmonary arterial hypertension patients in comparison to matched healthy controls and unaffected bone morphogenetic protein receptor type 2 mutation carriers. ¹⁸FLT-PET scanning was performed in 21 pulmonary arterial hypertension patients (15 hereditary pulmonary arterial hypertension and 6 idiopathic pulmonary arterial hypertension), 11 unaffected mutation carriers and 9 healthy control subjects. In-depth kinetic analysis indicated that there were no differences in lung ¹⁸FLT k3 phosphorylation among pulmonary arterial hypertension patients, unaffected bone morphogenetic protein receptor type 2 mutation carriers and healthy controls. Lung ¹⁸FLT uptake did not correlate with haemodynamic or clinical parameters in pulmonary arterial hypertension patients. Sequential ¹⁸FLT-PET scanning in three patients demonstrated uneven regional distribution in ¹⁸FLT uptake by 3D parametric mapping of the lung, although this did not follow the clinical course of the patient. We did not detect significantly increased lung ¹⁸FLT uptake in pulmonary arterial hypertension patients, nor in the unaffected bone morphogenetic protein receptor type 2 mutation carriers, as compared to healthy subjects. The conflicting results with our preliminary human ¹⁸FLT report may be explained by a small sample size previously and we observed large variation of lung ¹⁸FLT signals between patients, challenging the application of ¹⁸FLT-PET as a biomarker in the pulmonary arterial hypertension clinic.

Animal models of pulmonary hypertension: Getting to the heart of the problem

Despite recent therapeutic advances, pulmonary hypertension (PH) remains a fatal disease due to the development of right ventricular (RV) failure. At present, no treatments targeted at the right ventricle are available, and RV function is not widely considered in the preclinical assessment of new therapeutics. Several small animal models are used in the study of PH, including the classic models of exposure to either hypoxia or monocrotaline, newer combinational and genetic models, and pulmonary artery banding, a surgical model of pure RV pressure overload. These models reproduce selected features of the structural remodelling and functional decline seen in patients and have provided valuable insight into the pathophysiology of RV failure. However, significant reversal of remodelling and improvement in RV function remains a therapeutic obstacle. Emerging animal models will provide a deeper understanding of the mechanisms governing the transition from adaptive remodelling to a failing right ventricle, aiding the hunt for druggable molecular targets.

Risk Reduction and Hemodynamics with Initial Combination Therapy in Pulmonary Arterial Hypertension

Rationale: An initial oral combination of drugs is being recommended in pulmonary arterial hypertension (PAH), but the effects of this approach on risk reduction and pulmonary vascular resistance (PVR) are not known.Objectives: To test the hypothesis that a low-risk status would be determined by the reduction of PVR in patients with PAH treated upfront with a combination of oral drugs.Methods: The study enrolled 181 treatment-naive patients with PAH (81% idiopathic) with a follow-up right heart catheterization at 6 months (interquartile range, 144-363 d) after the initial combination of endothelin receptor antagonist + phosphodiesterase-5 inhibitor drugs and clinical evaluation and risk assessments by European guidelines and Registry to Evaluate Early and Long-Term PAH Disease Management scores.Measurements and Main Results: Initial combination therapy improved functional class and 6-minute-walk distance and decreased PVR by an average of 35% (median, 40%). One-third of the patients had a decrease in PVR <25%. This poor hemodynamic response was independently predicted by age, male sex, pulmonary artery pressure and cardiac index, and at echocardiography, a right/left ventricular surface area ratio of greater than 1 associated with low tricuspid annular plane systolic excursion of less than 18 mm. A low-risk status at 6 months was achieved or maintained in only 34.8% (Registry to Evaluate Early and Long-Term PAH Disease Management score) to 43.1% (European score) of the patients. Adding criteria of poor hemodynamic response improved prediction of a low-risk status.Conclusions: A majority of patients with PAH still insufficiently improved after 6 months of initial combinations of oral drugs is identifiable at initial evaluation by hemodynamic response criteria added to risk scores.

The Growing Role of Echocardiography in Pulmonary Arterial Hypertension Risk Stratification: The Missing Piece

Pulmonary arterial hypertension (PAH) is a rare, progressive disease with a poor prognosis. The pathophysiologic model is mainly characterized by an afterload mismatch in which an increased right ventricle afterload, driven by increased pulmonary vascular resistance (PVR), leads to right heart failure. International guidelines recommend optimization of treatment based on regular risk assessments to achieve or maintain a low-risk status. Current risk scores are based on a multi-modality approach, including demographic, clinical, functional, exercise, laboratory, and hemodynamic parameters, which lack significant echocardiographic parameters. The originality of echocardiography relies on the opportunity to assess in a non-invasive way a physiologically meaningful combination of easy to measure variables tightly related to right ventricle adaptation/maladaptation to increased afterload, the main determinant of a patient's prognosis. Echo-derived morphological and functional parameters have been investigated in PAH, proving to have prognostic relevance. Different therapeutic strategies proved to have different effects in reducing PVR. An upfront combination of drugs, including a parenteral prostacyclin, has shown to be associated with right heart reverse remodeling in a greater proportion of patients than other treatment strategies as a function of PVR reduction. Adding echocardiographic data to current risk scores would allow better identification of right ventricle (RV) adaptation in PAH patients' follow-up. This additional information would allow better stratification of the patient, leading to optimized and personalized therapeutic management.

Right Heart Size and Right Ventricular Reserve in Pulmonary Hypertension: Impact on Management and Prognosis

Various parameters reflecting right heart size, right ventricular function and capacitance have been shown to be prognostically important in patients with pulmonary hypertension (PH). In the advanced disease, patients suffer from right heart failure, which is a main reason for an impaired prognosis. Right heart size has shown to be associated with right ventricular function and reserve and is correlated with prognosis in patients with PH. Right ventricular reserve, defined as the ability of the ventricle to adjust to exercise or pharmacologic stress, is expressed by various parameters, which may be determined invasively by right heart catheterization or by stress-Doppler-echocardiography as a noninvasive approach. As the term "right ventricular contractile reserve" may be misleading, "right ventricular output reserve" seems desirable as a preferred term of increase in cardiac output during exercise. Both right heart size and right ventricular reserve have been shown to be of prognostic importance and may therefore be useful for risk assessment in patients with pulmonary hypertension. In this article we aim to display different aspects of right heart size and right ventricular reserve and their prognostic role in PH.

[Advantages and limitations of initial combination therapy in pulmonary arterial hypertension patients in Russia]

Pulmonary arterial hypertension (PAH) is severe and often times rapidly progressive disease with fatal outcome. The concept of initial combination of PAH-specific therapies in high risk patients at baseline was first described in the European guidelines on pulmonary hypertension (PH) in 2009, and in low or intermediate risk patients at baseline in 2015. Interestingly, that in Cologne Experts Consensus, and then in the 6th World Symposium on PH medical community started considering initial combination therapy as one of the most important pillars in PAH treatment algorithms in 2018. As of August 2020, as many as 8 formulations of 7 reference PAH-specific drugs are licensed for medical use in the Russian Federation. On top of that, 6 abbreviated drugs (generics) have also become available few years ago. Unfortunately, intravenous and subcutaneous prostacyclin analogs (PCA) and tadalafil are not approved for PH patients treatment in the Russian Federation. In this narrative review paper we attempted to describe studies on initial dual combination therapy with PAH-specific drugs registered in Russia, i.e. ambrisentan and riociguat, macitentan and riociguat, macitentan and sildenafil in low or intermediate risk patients at baseline, as well as iloprost inhaled and sildenafil, iloprost inhaled and bosentan in high risk patients. Some beneficial pharmacological effects due to the synergy between ambrisentan plus riociguat, and inhaled iloprost plus sildenafil appear to be interesting and require further clinical confirmation. Other initial combinations of PAH-specific agents require large-scale clinical trials as well.

Effects of macitentan and tadalafil monotherapy or their combination on the right ventricle and plasma metabolites in pulmonary hypertensive rats

Pulmonary arterial hypertension is a severe respiratory disease characterized by pulmonary artery remodeling. RV dysfunction and dysregulated circulating metabolomics are associated with adverse outcomes in pulmonary arterial hypertension. We investigated effects of tadalafil and macitentan alone or in combination on the RV and plasma metabolomics in SuHx and PAB models. For SuHx model, rats were injected with SU5416 and exposed to hypoxia for three weeks and then were returned to normoxia and treated with either tadalafil (10 mg/kg in chow) or macitentan (10 mg/kg in chow) or their combination (both 10 mg/kg in chow) for two weeks. For PAB model, rats were subjected to either sham or PAB surgery for three weeks and treated with above-mentioned drugs from week 1 to week 3. Following terminal echocardiographic and hemodynamic measurements, tissue samples were collected for metabolomic, histological and gene expression analysis. Both SuHx and PAB rats developed RV remodeling/dysfunction with severe and mild plasma metabolomic alterations, respectively. In SuHx rats, tadalafil and macitentan alone or in combination improved RV remodeling/function with the effects of macitentan and combination therapy being superior to tadalafil. All therapies similarly attenuated SuHx-induced changes in plasma metabolomics. In PAB rats, only macitentan improved RV remodeling/function, while only tadalafil attenuated PAB-induced changes in plasma metabolomics.

The Value of Hemodynamic Measurements or Cardiac MRI in the Follow-up of Patients With Idiopathic Pulmonary Arterial Hypertension

Background

Treatment of patients with pulmonary arterial hypertension (PAH) is conventionally based on functional plus invasive measurements obtained during right heart catheterization (RHC). Whether risk assessment during repeated measurements could also be performed on the basis of imaging parameters is unclear, as a direct comparison of strategies is lacking.

Research Question

How does the predictive value of noninvasive parameters compare with that of invasive hemodynamic measurements 1 year after the diagnosis of idiopathic PAH?

Study Design and Methods

One hundred and eighteen patients with idiopathic PAH who underwent RHC and cardiac MRI (CMR) were included in this study (median time between baseline evaluation and first parameter measures, 1.0 [0.8-1.2] years). Forty-four patients died or underwent lung transplantation. Forward Cox regression analyses were done to determine the best predictive functional, hemodynamic, and/or imaging model. Patients were classified as high risk if the event occurred < 5 years after diagnosis (n = 24), whereas patients without event were classified as low risk.

Results

A prognostic model based on age, sex, and absolute values at follow-up of functional parameters (6-min walk distance) performed well (Akaike information criterion [AIC], 279; concordance, 0.67). Predictive models with only hemodynamic (right atrial pressure, mixed venous oxygen saturation; AIC, 322; concordance, 0.66) or imaging parameters (right ventricular ejection fraction; AIC, 331; concordance, 0.63) at 1 year of follow-up performed similarly. The predictive value improved when functional data were combined with either hemodynamic data (AIC, 268; concordance, 0.69) or imaging data (AIC, 273; concordance, 0.70). A model composed of functional, hemodynamic, and imaging data performed only marginally better (AIC, 266; concordance, 0.69). Finally, changes between baseline and 1-year follow-up were observed for multiple hemodynamic and CMR parameters; only a change in CMR parameters was of prognostic predictive value.

Interpretation

At 1 year of follow-up, risk assessment based on CMR is at least equal to risk assessment based on RHC. In this study, only changes in CMR, but not hemodynamic parameters, were of prognostic predictive value during the first year of follow-up.

Early return of reflected waves increases right ventricular wall stress in chronic thromboembolic pulmonary hypertension

Pulmonary vascular resistance (PVR) and compliance are comparable in proximal and distal chronic thromboembolic pulmonary hypertension (CTEPH). However, proximal CTEPH is associated with inferior right ventricular (RV) adaptation. Early wave reflection in proximal CTEPH may be responsible for altered RV function. The aims of the study are as follows: 1) to investigate whether reflected pressure returns sooner in proximal than in distal CTEPH and 2) to elucidate whether the timing of reflected pressure is related to RV dimensions, ejection fraction (RVEF), hypertrophy, and wall stress. Right heart catheterization and cardiac MRI were performed in 17 patients with proximal CTEPH and 17 patients with distal CTEPH. In addition to the determination of PVR, compliance, and characteristic impedance, wave separation analysis was performed to determine the magnitude and timing of the peak reflected pressure (as %systole). Findings were related to RV dimensions and time-resolved RV wall stress. Proximal CTEPH was characterized by higher RV volumes, mass, and wall stress, and lower RVEF. While PVR, compliance, and characteristic impedance were similar, proximal CTEPH was related to an earlier return of reflected pressure than distal CTEPH (proximal 53 ± 8% vs. distal 63 ± 15%, P < 0.05). The magnitude of the reflected pressure waves did not differ. RV volumes, RVEF, RV mass, and wall stress were all related to the timing of peak reflected pressure. Poor RV function in patients with proximal CTEPH is related to an early return of reflected pressure wave. PVR, compliance, and characteristic impedance do not explain the differences in RV function between proximal and distal CTEPH.NEW & NOTEWORTHY In chronic thromboembolic pulmonary hypertension (CTEPH), proximal localization of vessel obstructions is associated with poor right ventricular (RV) function compared with distal localization, though pulmonary vascular resistance, vascular compliance, characteristic impedance, and the magnitude of wave reflection are similar. In proximal CTEPH, the RV is exposed to an earlier return of the reflected wave. Early wave reflection may increase RV wall stress and compromise RV function.

Heart rate monitoring improves clinical assessment during 6-min walk

Right ventricular (RV) function is a predictor of outcomes in pulmonary arterial hypertension (PAH). The 6-min walk test (6MWT) is likely an indirect measure of RV function during exercise, but changes in absolute walk distance can also be influenced by factors like effort and musculoskeletal disease. Paired 6MWT with continuous electrocardiogram monitoring was performed in stable PAH patients, patients adding PAH therapies, and healthy controls. Heart rate expenditure (HRE) was calculated (integrating pulse during 6MWT) and then divided by walk distance (HRE/d). We also evaluated changes in peak heart rate, time above age-adjusted maximum predicted heart rate, and heart rate at 6 min. HRE/d was compared to invasive hemodynamic measures in patients who had right heart catheterization performed within seven days, WHO functional class assessment, and Emphasis 10 questionnaire. We measured two 6MWT in 15 stable PAH patients, 13 treatment intensification patients, and 8 healthy controls. HRE/d was reproducible in the stable PAH group (median difference, -0.79%), while it decreased (median difference, 23%, p = 0.0001) after adding vasodilator therapy. In 11 patients with right heart catheterization, HRE/d correlated strongly with stroke volume, r = -0.72, p = 0.01. Peak heart rate decreased after adding vasodilator therapy. HRE/d also correlated with WHO functional class and Emphasis 10 score. Continuous heart rate monitoring during 6MWT provides valuable physiologic data accounting for effort. HRE/d appears to enhance test reproducibility in stable patients while detecting change after adding therapy as compared to walk distance alone.

Allopurinol in Patients with Pulmonary Hypertension Associated with Chronic Lung Disease

Background

Oxidative stress (OS) has been implicated in the development of pulmonary hypertension (PH) and ventricular hypertrophy. Xanthine oxidase is a well-recognised source of reactive oxygen species, which lead to OS. The aim of this proof of concept study was to assess whether allopurinol (xanthine oxidase inhibitor) would reduce right ventricular mass (RVM) in patients with PH-associated chronic lung disease (PH-CLD).

Methods

We conducted a randomised, double-blind, parallel-group, placebo-controlled trial in patients with PH-CLD (93% COPD, 7% IPF) who were randomly assigned to receive allopurinol or placebo for 12 months. The primary outcome was the mean change in RVM, as assessed by cardiac magnetic resonance imaging (CMRI). Secondary outcomes included quality of life (QOL), spirometry and six-minute walk test (6MWT).

Results

Seventy-one patients were recruited: mean age 71 years, mean pulmonary arterial pressure 30 mm Hg, FEV₁ 60% and resting SpO₂ 96%. After 12 months, there was no significant difference in the change in RVM from baseline (allopurinol 1.85g vs placebo 0.97g with mean difference 0.88g, CI −4.77 to 3.01, p =0.7). There were also no significant changes in other cardiac parameters measured on MRI, in QOL, spirometry and 6MWT. Subgroup analysis showed that allopurinol significantly reduced RVM compared to placebo with -6.16g vs 0.75g and mean difference 6.92g (CI 1.14 to 12.69, p = 0.02) in COPD patients with more severe airflow limitation.

Conclusion

Allopurinol had no overall impact on patients with PH-CLD but had potential benefit in COPD patients with more severe airflow limitation.

Initial combination therapy of macitentan and tadalafil in pulmonary arterial hypertension

Initial combination therapy plays a central role in managing pulmonary arterial hypertension (PAH) [1–4]. Patients with low- or intermediate-risk of 1-year mortality at diagnosis should be treated with initial combination therapy with an endothelin receptor antagonist (ERA) and phosphodiesterase type-5 inhibitor (PDE5i) [2–4]. Benefits of initial therapy with the ERA ambrisentan and PDE5i tadalafil were demonstrated in AMBITION [1]; prospective evidence for other treatment combinations within these drug classes is needed.

Initial combination therapy with macitentan and tadalafil is well tolerated and improves cardiopulmonary haemodynamics and functional capacity in newly diagnosed PAH patientshttps://bit.ly/3aWZagH

Initial combination therapy of macitentan and tadalafil in pulmonary arterial hypertension

Initial combination therapy with macitentan and tadalafil is well tolerated and improves cardiopulmonary haemodynamics and functional capacity in newly diagnosed PAH patients https://bit.ly/3aWZagH

Hemodynamics and risk assessment 2 years after the initiation of upfront ambrisentan‒tadalafil in pulmonary arterial hypertension

BACKGROUND

Upfront combination therapy with ambrisentan and tadalafil has been reported to improve the condition of patients with pulmonary arterial hypertension (PAH) more than with either drug alone. However, little is known about the long-term associated changes in hemodynamics and risk assessment scores.

METHODS

This was a multicenter, retrospective analysis of clinical data in 106 patients with newly diagnosed PAH. Clinical evaluations, including demographics, medical history, World Health Organization (WHO) functional class (FC) and 6-minute walk distance (6MWD), right heart catheterization, and Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) risk score 2.0, were assessed over 48 months of ambrisentan‒tadalafil therapy.

RESULTS

At baseline, 9 patients (9%) showed a low (<7), 48 patients (45%) showed an intermediate (7-8), and 49 patients (46%) showed a high (>8) REVEAL risk score. At a median follow-up of 2 years, 45 patients (43%) showed a low, 47 patients (44%) showed an intermediate, and 14 patients (13%) showed a high REVEAL score, along with improvements in WHO FC, 6MWD and a decrease in mean pulmonary artery pressure and N-terminal pro brain natriuretic peptide (all p < 0.001). Pulmonary vascular resistance (PVR) decreased by 37% from 11.5 ± 6.5 to 7.2 ± 4.1 Wood units (p < 0.001). A total of 61 patients (57%) remained in intermediate-risk or high-risk categories. Low-risk patients had either a decrease in PVR of >50% or a stroke volume within the limits of normal.

CONCLUSIONS

Initial combination therapy with ambrisentan and tadalafil in PAH improves the REVEAL risk score in proportion to decreased PVR and preserved stroke volume but still insufficiently so in approximately 50% of the patients.

Emerging role of cardiovascular magnetic resonance imaging in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a clinical condition characterised by elevation of pulmonary arterial pressure (PAP) above normal range due to various aetiologies. While cardiac right-heart catheterisation (RHC) remains the gold standard and mandatory for establishing the diagnosis of PH, noninvasive imaging of the heart plays a central role in the diagnosis and management of all forms of PH. Although Doppler echocardiography (ECHO) can measure a range of haemodynamic and anatomical variables, it has limited utility for visualisation of the pulmonary artery and, oftentimes, the right ventricle. Cardiovascular magnetic resonance (CMR) provides comprehensive information about the anatomical and functional aspects of the pulmonary artery and right ventricle that are of prognostic significance for assessment of long-term outcomes in disease progression. CMR is suited for serial follow-up of patients with PH due to its noninvasive nature, high sensitivity to changes in anatomical and functional parameters, and high reproducibility. In recent years, there has been growing interest in the use of CMR derived parameters as surrogate endpoints for early-phase PH clinical trials. This review will discuss the role of CMR in the diagnosis and management of PH, including current applications and future developments, in comparison to other existing major imaging modalities.

Effect of Combination Therapy of Endothelin Receptor Antagonist and Phosphodiesterase-5 Inhibitor on Clinical Outcome and Pulmonary Haemodynamics in Patients with Pulmonary Arterial Hypertension: A Meta-Analysis

BACKGROUND

The combination of an endothelin receptor antagonist and a phosphodiesterase-5 inhibitor having different biological targets has become an integral part of the treatment of pulmonary arterial hypertension; however, several clinical studies have reported conflicting results.

OBJECTIVE

The objective of this meta-analysis was to evaluate the effect of an endothelin receptor antagonist and phosphodiesterase-5 inhibitor combination in pulmonary arterial hypertension.

METHODS

After performing a comprehensive literature search in MEDLINE, Cochrane and the International Clinical Trial Registry Platform, reviewers assessed eligibility and extracted data from seven relevant articles (publications till December 2018). PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed in the selection, analysis and reporting of findings. The odds ratio and mean difference were calculated to estimate the difference in clinical worsening, 6-minute walking distance, pulmonary vascular resistance and N-terminal pro-brain natriuretic peptide between the groups. Quality assessment was performed using the risk of bias assessment tool and a meta-regression for probable variables affecting effect size.

RESULTS

The random-effect model analysis revealed an odds ratio of 0.56 [95% confidence interval (CI) 0.41-0.76; p = 0.0002] for clinical worsening, mean difference of 15.64 (95% CI 2.67-28.61; p = 0.02) for 6-minute walking distance, - 1.66 (95% CI - 3.82 to 0.50; p = 0.13) for pulmonary vascular resistance and - 21.04 (95% CI - 26.87 to - 15.22; p < 0.00001) for N-terminal pro-brain natriuretic peptide. The meta-regression showed no statistically significant association between the dose and duration of treatment and outcomes (odds ratio of clinical worsening and mean difference of 6-minute walking distance).

CONCLUSIONS

In pulmonary arterial hypertension, endothelin receptor antagonist and phosphodiesterase-5 inhibitor combination therapy significantly improved 6-minute walking distance, clinical worsening and N-terminal pro-brain natriuretic peptide compared with the monotherapy but did not offer any advantage in improving pulmonary vascular resistance.

PROSPERO REGISTRATION NO

CRD42018091133.

Right ventricular function in pulmonary (arterial) hypertension

The right ventricle (RV) is the main determinant of prognosis in pulmonary hypertension. Adaptation and maladaptation of the RV are of crucial importance. In the course of disease, RV contractility increases through changes in muscle properties and muscle hypertrophy. At a certain point, the point of "uncoupling," the afterload exceeds contractility, and maladaptation as well as dilation occurs to maintain stroke volume (SV). To understand the adaptational processes and to further develop targeted medication directly affecting load-independent contractility, an accurate and precise assessment of contractility and RV-pulmonary artery (PA) coupling should be performed. In this review, we shed light on existing methods to assess RV function, including the gold standard measurement of contractility and RV-PA coupling, and we evaluate existing surrogates of RV-PA coupling.

15 years journey of idiopathic pulmonary arterial hypertension with BMPR2 mutation

Pulmonary arterial hypertension (PAH) is known as one of diseases with the worst prognosis. Recently, targeted PAH drugs have been developed and approved for use; therefore, the treatment strategy and goals have changed, and the prognosis has improved over two decades. We reviewed the case of a female who showed the natural disease course of heritable PAH in treatment with the targeted PAH drugs under the Korean Health Insurance policy. At the age of 15, she visited the outpatient clinic for dyspnea on exertion that occurred 3 years ago. At that time, severe pulmonary hypertension was revealed by an echocardiography and there was no evidence of significant shunt lesion or embolism. After 4 years of loss to follow-up, her performance was WHO functional class III and she still suffered from dyspnea. The initial monotherapy using an endothelin receptor antagonist was started in 2008. After 2 years, BMPR 2 mutation was detected. Her clinical symptoms gradually worsened because of poor compliance. To escalate therapy, combination therapy was given, and finally, triple maximal therapy was maintained. The next step is to consider intravenous prostanoids. Various combinations of targeted therapy have been tried, and several trials have been confirmed that improve the prognosis. Initial upfront combination therapy and a more enthusiastic approach make good a better prognosis. In this area, active support of the government insurance policy is indispensable in Korea.

Risk Reduction and Right Heart Reverse Remodeling by Upfront Triple Combination Therapy in Pulmonary Arterial Hypertension

BACKGROUND

Combinations of therapies are currently recommended for patients with severe pulmonary arterial hypertension (PAH), and excellent results have been reported with triple upfront combination of these drugs. We evaluated the effects of this approach on right ventricular (RV) function and outcome in patients with severe PAH.

METHODS

Twenty-one patients (age, 44 ± 15 years) with newly diagnosed high-risk idiopathic PAH that was nonreversible by the inhalation of nitric oxide were treated upfront with a combination of ambrisentan, tadalafil, and subcutaneous treprostinil between 2014 and 2018. Clinical evaluation, World Health Organization functional class, 6-min walk distance, biomarkers, echocardiography, and right-sided heart catheterization data were recorded at baseline and during follow-up.

RESULTS

At a median follow-up of 2 years, all patients were still alive. The Registry to Evaluate Early and Long-term Pulmonary Arterial Hypertension Disease Management score decreased from 10 ± 1 to 5 ± 1, right-sided atrial pressure decreased from 13 ± 3 to 5 ± 2 mm Hg, mean pulmonary artery pressure decreased from 60 ± 9 to 42 ± 5 mm Hg, pulmonary vascular resistance (PVR) decreased from 16.4 ± 4.4 to 5.5 ± 1.3 Wood units, N-terminal pro-brain natriuretic peptide decreased from 3,379 ± 1,921 to 498 ± 223 pg/mL, and World Health Organization functional class decreased from 3.4 ± 0.5 to 2.0 ± 0.4 (all P < .001). Cardiac index increased from 1.8 ± 0.3 to 3.5 ± 0.8 L/min/m² and 6-min walk distance increased from 158 ± 130 to 431 ± 66 m (both P < .001). Echocardiography showed decreased right-sided atrial and RV areas, improved left ventricular eccentricity index, and increased fractional area change (all P < .001) in proportion to treatment-induced decrease in PVR.

CONCLUSIONS

Triple upfront combination therapy with ambrisentan, tadalafil, and subcutaneous treprostinil in severe nonreversible PAH is associated with considerable clinical and hemodynamic improvement and right-sided heart reverse remodeling.

The right treatment for the right ventricle

PURPOSE OF REVIEW

Right ventricular (RV) function is an important determinant of morbidity and mortality in patients with pulmonary arterial hypertension (PAH). Although substantial progress has been made in understanding the development of RV failure in the last decennia, this has not yet resulted in the development of RV selective therapies. In this review, we will discuss the current status on the treatment of RV failure and potential novel therapeutic strategies that are currently being investigated in clinical trials.

RECENT FINDINGS

Increased afterload results in elevated wall tension. Consequences of increased wall tension include autonomic disbalance, metabolic shift and inflammation, negatively affecting RV contractility. Compromised RV systolic function and low cardiac output activate renin-angiotensin aldosterone system, which leads to fluid retention and further increase in RV wall tension. This vicious circle can be interrupted by directly targeting the determinants of RV wall tension; preload and afterload by PAH-medications and diuretics, but is also possibly by restoring neurohormonal and metabolic disbalance, and inhibiting maladaptive inflammation. A variety of RV selective drugs are currently being studied in clinical trials.

SUMMARY

Nowadays, afterload reduction is still the cornerstone in treatment of PAH. New treatments targeting important pathobiological determinants of RV failure directly are emerging.