Right ventricular size and function under riociguat in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (the RIVER study)

Chronic thromboembolic pulmonary hypertension and balloon pulmonary angioplasty - Where are we in 2024?

Pulmonary endarterectomy (PEA) is the first-line treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, some patients with CTEPH are considered inoperable, and in the last decade, balloon pulmonary angioplasty (BPA) has emerged as a viable therapeutic option for these patients with prohibitive surgical risk or recurrent pulmonary hypertension following PEA. Numerous international centers have increased their procedural volume of BPA and have reported improvements in pulmonary hemodynamics, patient functional class and right ventricular function. Randomized controlled trials have also demonstrated similar findings. Recent refinements in procedural technique, increased operator experience and advancements in procedural technology have facilitated marked reduction in the risk of complications following BPA. Current guidelines recommend BPA for patients with inoperable CTEPH and persistent pulmonary hypertension following PEA. The pulmonary arterial endothelium plays a vital role in the pathophysiologic development and progression of CTEPH.

The nitric oxide-soluble guanylate cyclase-cGMP pathway in pulmonary hypertension: from PDE5 to soluble guanylate cyclase

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway plays a key role in the pathogenesis of pulmonary hypertension (PH). Targeted treatments include phosphodiesterase type 5 inhibitors (PDE5i) and sGC stimulators. The sGC stimulator riociguat is approved for the treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). sGC stimulators have a dual mechanism of action, enhancing the sGC response to endogenous NO and directly stimulating sGC, independent of NO. This increase in cGMP production via a dual mechanism differs from PDE5i, which protects cGMP from degradation by PDE5, rather than increasing its production. sGC stimulators may therefore have the potential to increase cGMP levels under conditions of NO depletion that could limit the effectiveness of PDE5i. Such differences in mode of action between sGC stimulators and PDE5i could lead to differences in treatment efficacy between the classes. In addition to vascular effects, sGC stimulators have the potential to reduce inflammation, angiogenesis, fibrosis and right ventricular hypertrophy and remodelling. In this review we describe the evolution of treatments targeting the NO-sGC-cGMP pathway, with a focus on PH.

Modulating NO-GC Pathway in Pulmonary Arterial Hypertension

The pathogenesis of complex diseases such as pulmonary arterial hypertension (PAH) is entirely rooted in changes in the expression of some vasoactive factors. These play a significant role in the onset and progression of the disease. Indeed, PAH has been associated with pathophysiologic alterations in vascular function. These are often dictated by increased oxidative stress and impaired modulation of the nitric oxide (NO) pathway. NO reduces the uncontrolled proliferation of vascular smooth muscle cells that leads to occlusion of vessels and an increase in pulmonary vascular resistances, which is the mainstay of PAH development. To date, two classes of NO-pathway modulating drugs are approved for the treatment of PAH: the phosphodiesterase-5 inhibitors (PD5i), sildenafil and tadalafil, and the soluble guanylate cyclase activator (sGC), riociguat. Both drugs provide considerable improvement in exercise capacity and pulmonary hemodynamics. PD5i are the recommended drugs for first-line PAH treatment, whereas sGCs are also the only drug approved for the treatment of resistant or inoperable chronic thromboembolic pulmonary hypertension. In this review, we will focus on the current information regarding the nitric oxide pathway and its modulation in PAH.

Modulation of the nitric oxide/cGMP pathway in cardiac contraction and relaxation: Potential role in heart failure treatment

Evidence exists that heart failure (HF) has an overall impact of 1-2 % in the global population being often associated with comorbidities that contribute to increased disease prevalence, hospitalization, and mortality. Recent advances in pharmacological approaches have significantly improved clinical outcomes for patients with vascular injury and HF. Nevertheless, there remains an unmet need to clarify the crucial role of nitric oxide/cyclic guanosine 3',5'-monophosphate (NO/cGMP) signalling in cardiac contraction and relaxation, to better identify the key mechanisms involved in the pathophysiology of myocardial dysfunction both with reduced (HFrEF) as well as preserved ejection fraction (HFpEF). Indeed, NO signalling plays a crucial role in cardiovascular homeostasis and its dysregulation induces a significant increase in oxidative and nitrosative stress, producing anatomical and physiological cardiac alterations that can lead to heart failure. The present review aims to examine the molecular mechanisms involved in the bioavailability of NO and its modulation of downstream pathways. In particular, we focus on the main therapeutic targets and emphasize the recent evidence of preclinical and clinical studies, describing the different emerging therapeutic strategies developed to counteract NO impaired signalling and cardiovascular disease (CVD) development.

Riociguat and the right ventricle in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are progressive diseases that can lead to right heart failure and death. Right ventricular dysfunction, hypertrophy and maladaptive remodelling are consequences of increased right ventricular (RV) afterload in PAH and CTEPH and are indicative of long-term outcomes. Because RV failure is the main cause of morbidity and mortality in PAH and CTEPH, successful treatments should lead to improvements in RV parameters. Riociguat is a soluble guanylate cyclase stimulator approved for the treatment of PAH and inoperable or persistent/recurrent CTEPH after pulmonary endarterectomy. This review examines the current evidence showing the effect of riociguat on the right ventricle, with particular focus on remodelling, function and structural parameters in preclinical models and patients with PAH or CTEPH.

A Comprehensive Assessment of Right Ventricular Function in Chronic Thromboembolic Pulmonary Hypertension

While chronic thromboembolic pulmonary hypertension (CTEPH) results from macroscopic and microscopic obstruction of the pulmonary vascular bed, the function of the right ventricle (RV) and increased RV afterload are the main determinants of its symptoms and prognosis. In this review, we assess RV function in patients diagnosed with CTEPH with a focus on the contributions of RV afterload and dysfunction to the pathogenesis of this disease. We will also discuss changes in RV function and geometry in response to treatment, including medical therapy, pulmonary endarterectomy, and balloon pulmonary angioplasty.

Selexipag-based triple combination therapy improves prognosis in Chinese pulmonary arterial hypertension patients

Aim

Selexipag is an oral selective prostacyclin receptor agonist approved for treatment of patients with pulmonary arterial hypertension (PAH). In the present study, we aim to assess the safety and efficacy of selexipag in triple combination therapy with endothelial receptor antagonists (ERAs) and PDE5is for Chinese PAH patients.

Methods and results

A single center retrospective study was performed on group 1 PAH patients (n = 68) initiating triple combination therapy with selexipag from 1 February 2020 to 31 August 2021 in Qilu Hospital of Shandong University (Shandong, China). Adolescents, children, and PAH patients with unrepaired congenital heart disease were excluded. The French pulmonary hypertension network (FPHN) non-invasive risk assessment, echocardiogram parameters, and clinical data, including tolerability, safety, and death/hospitalization events associated with PAH, were collected. Of the 68 patients, 31 (45.6%) patients had tolerable side effects while only a single patient discontinued selexipag due to severe diarrhea. In the analysis of the efficacy set of 62 patients, the median selexipag treatment time from selexipag initiation to last risk assessment was 27 (21, 33) weeks. Compared to baseline parameters, the percentage of WHO FC III/IV decreased from 77.4% (48) to 24.2% (15) (p = 0.000), median 6-min walk distance (6MWD) increased 82 m [from 398 (318, 450) to 480 (420, 506) m; p = 0.000], and NT-proBNP levels decreased from 1,216 (329, 2,159) to 455 (134, 1,678) pg/mL (p = 0.007). Patients who improved to three low-risk criteria increased from 9.7 to 38.7%. Right ventricular diameter (RV) diameter also decreased and was accompanied by an improved tricuspid annular plane systolic excursion (TAPSE). Patients transitioning from subcutaneous treprostinil to selexipag continued to show improvements in WHO FC, 6MWD (404 ± 94 vs. 383 ± 127 m) and NT-proBNP levels (2,319 ± 2,448 vs. 2,987 ± 3,770 pg/mL). Finally, the 1-year event free survival rate was 96.7% for patients initiating the triple combination therapy within 3 years of PAH diagnosis.

Conclusion

Triple combination therapy with selexipag was safe and effective in Chinese PAH patients, which was confirmed by acceptable tolerability, and improved exercise capacity, right heart function, risk assessment, and prognosis.

Right ventricle remodeling in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is an underdiagnosed, but potentially curable pulmonary vascular disease. The increased pulmonary vascular resistance in CTEPH is caused by unresolved proximal thrombus and secondary microvasculopathy in the pulmonary vasculature, leading to adaptive and maladaptive remodeling of the right ventricle (RV), eventual right heart failure, and death. Knowledge on the RV remodeling process in CTEPH is limited. The progression to RV failure in CTEPH is a markedly slower process. A detailed understanding of the pathophysiology and underlying mechanisms of RV remodeling may facilitate early diagnosis and the development of targeted therapy. While ultrasound, magnetic resonance imaging, right heart catheterization, and serum biomarkers have been used to assess cardiac function, the current treatment strategies reduce the afterload of the right heart, but are less effective in improving the maladaptive remodeling of the right heart. This review systematically summarizes the current knowledge on adaptive and maladaptive remodeling of the right heart in CTEPH from molecular mechanisms to clinical practice.

Non-Invasive Risk Prediction Based on Right Ventricular Function in Patients with Pulmonary Arterial Hypertension

BACKGROUND

Right ventricular dysfunction is a major determinant of outcome in pulmonary arterial hypertension (PAH). We aimed to identify echocardiographic right heart parameters associated with adverse outcome and to develop a non-invasive, echocardiography-based risk score for PAH patients.

METHODS AND RESULTS

In 254 PAH patients we analyzed functional status, laboratory results, and echocardiographic parameters. We included these parameters to estimate all-cause death or lung transplantation using Cox regression models. The analyses included a conventional model using guideline-recommended variables and an extended echocardiographic model. Based on the final model a 12-point risk score was derived, indicating the association with the primary outcome within five years. During a median follow-up time of 4.2 years 74 patients died or underwent lung transplantation. The conventional model resulted in a C-Index of 0.539, whereas the extended echocardiographic model improved the discrimination (C-index 0.639, p-value 0.017). Ultimately, the newly developed risk score included WHO functional class, 6-min walking distance, N-terminal brain natriuretic peptide concentrations, pericardial effusion, right atrial area, tricuspid annular plane systolic excursion, and fractional area change.

CONCLUSION

Integrating right heart function assessed by echocardiography improves prediction of death or lung transplantation in PAH patients. Independent validation of this finding is warranted.

Haemodynamic effects of riociguat in CTEPH and PAH: a 10-year observational study

Background

Long-term treatment with riociguat has been shown to enhance exercise capacity in patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH). This study sought to evaluate the long-term haemodynamic effects of riociguat in patients with PAH and inoperable CTEPH.

Methods

During this single-centre long-term observational study, riociguat was administered at a three-times-daily dose of up to 2.5 mg. The primary outcome was pulmonary vascular resistance (PVR). The secondary outcomes included mean pulmonary arterial pressure (PAP), cardiac index, mortality, clinical worsening events, 6-min walk distance (6MWD) and World Health Organization functional class (WHO FC).

Results

37 patients (CTEPH n=19; PAH n=18) were included. The median follow-up period was 96 months. The survival estimates for all the patients at 1/3/5/8 years were 0.97/0.86/0.72/0.61, without significant differences between patients with CTEPH and PAH. At the final data cut-off, PVR decreased (1232±462 dyn·s·cm^–5versus 835±348 dyn·s·cm^–5, p<0.001), cardiac index increased (1.7±0.4 L·min⁻¹·m⁻²versus 2.4±0.5 L·min⁻¹·m⁻², p<0.001), 6MWD increased by 43.1±59.6 m, and WHO FC improved/stabilised/worsened in 40%/35%/25% of patients versus baseline. Improvement in PAP was not shown. Compared with patients in WHO FC I/II and III/IV at baseline, the 8-year clinical worsening-free survival estimates were 0.51 versus 0.19 (p=0.026).

Conclusions

Riociguat improved PVR and cardiac index for up to 8 years, but not PAP. WHO FC may have certain predictive value for the long-term prognosis.

In patients with PAH and inoperable CTEPH, riociguat improved pulmonary vascular resistance and cardiac index for 8 years, but not pulmonary arterial pressure. World Health Organization functional class may have predictive value for long-term prognosis.https://bit.ly/3dTf4ft

Can pulse wave velocity (PWV) alone express arterial stiffness? A neglected tool for vascular function assessment

Arterial stiffness, defined as the rigidity of the arterial wall, is the consequence of vascular aging and is associated with the full spectrum of cardiovascular diseases. Carotid-femoral pulse wave velocity (cf-PWV) is the gold standard method for arterial stiffness evaluation: it measures the velocity of the arterial pulse along the thoracic and abdominal aorta alongside arterial distensibility. Its value rises as stiffness progresses. Cf-PWV is helpful to assess residual cardiovascular risk (CVR) in hypertension (HT). In fact, an increase in pulsatility and arterial stiffness predicts CVR in patients affected by arterial HT, independently of other risk factors. Arterial stiffness can predict cardiovascular events in several other clinical conditions such as heart failure, diabetes, and pulmonary HT. However, cf-PWV has not been yet included in routine clinical practice so far. A possible reason might be its methodological and theoretical limitations (inaccuracy in the traveled distance, intra and interindividual variability, lack of well-defined references values, and age- and blood pressure-independent cutoff). To exceed these limits a strict adherence to guidelines, use of analytical approaches, and possibility of integrating the results with other stiffness examinations are essential approaches.

Effect of riociguat on right ventricular function in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension

BACKGROUND

In the Phase III PATENT-1 (NCT00810693) and CHEST-1 (NCT00855465) studies, riociguat demonstrated efficacy vs placebo in patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Clinical effects were maintained at 2 years in the long-term extension studies PATENT-2 (NCT00863681) and CHEST-2 (NCT00910429).

METHODS

This post hoc analysis of hemodynamic data from PATENT-1 and CHEST-1 assessed whether riociguat improved right ventricular (RV) function parameters including stroke volume index (SVI), stroke volume, RV work index, and cardiac efficiency. REVEAL Risk Score (RRS) was calculated for patients stratified by SVI and right atrial pressure (RAP) at baseline and follow-up. The association between RV function parameters and SVI and RAP stratification with long-term outcomes was assessed.

RESULTS

In PATENT-1 (n = 341) and CHEST-1 (n = 238), riociguat improved RV function parameters vs placebo (p < 0.05). At follow-up, there were significant differences in RRS between patients with favorable and unfavorable SVI and RAP, irrespective of treatment arm (p < 0.0001). Multiple RV function parameters at baseline and follow-up were associated with survival and clinical worsening-free survival (CWFS) in PATENT-2 (n = 396; p < 0.05) and CHEST-2 (n = 237). In PATENT-2, favorable SVI and RAP at follow-up only was associated with survival and CWFS (p < 0.05), while in CHEST-2, favorable SVI and RAP at baseline and follow-up were associated with survival and CWFS (p < 0.05).

CONCLUSION

This post hoc analysis of PATENT and CHEST suggests that riociguat improves RV function in patients with PAH and CTEPH.

Echocardiography in Pulmonary Arterial Hypertension: Is It Time to Reconsider Its Prognostic Utility?

Pulmonary arterial hypertension (PAH) is characterized by an insult in the pulmonary vasculature, with subsequent right ventricular (RV) adaptation to the increased afterload that ultimately leads to RV failure. The awareness of the importance of RV function in PAH has increased considerably because right heart failure is the predominant cause of death in PAH patients. Given its wide availability and reduced cost, echocardiography is of paramount importance in the evaluation of the right heart in PAH. Several echocardiographic parameters have been shown to have prognostic implications in PAH; however, the role of echocardiography in the risk assessment of the PAH patient is limited under the current guidelines. This review discusses the echocardiographic evaluation of the RV in PAH and during therapy, and its prognostic implications, as well as the potential significant role of repeated echocardiographic assessment in the follow-up of patients with PAH.

Efficacy and safety of riociguat in the treatment of chronic thromboembolic pulmonary arterial hypertension: A meta-analysis

BACKGROUND

Riociguat is a novel soluble guanylate cyclase stimulator, and has been widely used for the treatment of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (CTEPH). Some studies found that riociguat had better effects on CTEPH and proved to be safe, but the results were not utterly consistent. Therefore, the purpose of this study was to comprehensively evaluate the efficacy and safety of riociguat in the treatment of CTEPH.

METHODS

Randomized controlled trials on riociguat for the treatment of CTEPH were searched through such electronic databases as PubMed, Embase, Cochrane Library, Web of Science, China national knowledge internet, and Wanfang. The outcomes included exercise capacity, pulmonary hemodynamics, and side effects. The fixed-effects or random-effects models were used to analyze the pooled data, and heterogeneity was assessed by the I2 test.

RESULTS

Four studies involving 520 patients were included in this meta-analysis. Compared with the placebo group, riociguat significantly improved the hemodynamic indexes and increased 6-min walking distance (P < .0001, standardized mean difference (SMD) = -0.24, 95%CI -0.35 to -0.12; P < .00001, SMD = 0.52, 95%CI 0.33 to 0.71), and decreased the Borg dyspnea score (P = .002, SMD = -0.31, 95%CI -0.51 to -0.12). In addition, riociguat could also significantly reduce the living with pulmonary hypertension scores and increase the EQ-5D scores (P = .01, SMD=-0.23, 95%CI -0.42 to -0.05; P < .00001, SMD = 0.47, 95%CI 0.27 to 0.66), but there was no significant difference in the change level of N-terminal pro-hormone B-type natriuretic peptide in patients with riociguat (P = .20, SMD = -0.24, 95%CI -0.61 to -0.13). The common adverse events of riociguat were dyspepsia and peripheral edema, and no other serious adverse reactions were observed.

CONCLUSIONS

We confirmed that riociguat had better therapeutic effects in improving the hemodynamic parameters and exercise capacity in patients with CTEPH without inducing serious adverse events. This will provide a reasonable medication regimen for the treatment of CTEPH.

Mild pulmonary hypertension and premature mortality among 154 956 men and women undergoing routine echocardiography

Although mild pulmonary hypertension (PHT) is known to be associated with increased mortality, its impact on premature mortality is largely unknown.We studied the distribution of estimated right ventricular systolic pressures (eRVSP) among 154 956 adults with no evidence of left heart disease investigated with echocardiography. We then examined individually linked mortality, premature mortality and associated life-years lost (LYL) according to eRVSP levels.The cohort comprised 70 826 men (61.3±17.7 years) and 84 130 women (61.4±18.4 years). Overall, 85 173 (55.0%), 49 276 (31.8%), 13 060 (8.4%) and 7447 (4.8%) cases had an eRVSP level indicative of no (<30.0 mmHg), mild (30.0-39.9 mmHg), moderate (40.0-49.9 mmHg), or severe (≥50.0 mmHg) PHT, respectively. During median 5.7 (interquartile range 3.2-8.9) years follow-up, 38 456/154 986 (24.8%) individuals died. Compared to an eRVSP <30.0 mmHg, age and sex-adjusted hazard ratios for all-cause and cardiovascular-related mortality were 1.90 (95% CI 1.84-1.96) and 1.85 (95% CI 1.74-1.97) respectively, for an eRVSP of 35.0-39.9 mmHg. Overall, 6,256 (54%) men and 7524 (55%) women died prematurely. As a proportion of all deaths, premature mortality rose from 46.7% to 79.2% among those with an eRVSP <30.0 mmHg versus ≥60.0 mmHg with a mean of 5.1 to 11.4 LYL each time. However, due to more individuals affected overall, an eRVSP of 30.0-39.9 mmHg accounted for 58% and 53% of total LYL among men (40 606/70 019 LYL) and women (47 333/88 568 LYL), respectively.These data confirm that elevated eRVSP levels indicative of mild PHT are associated with increased risk of death. Moreover, this results in a substantive component of premature mortality/LYL that requires more proactive clinical surveillance and management.

Systemic Sclerosis-Associated Pulmonary Hypertension: Spectrum and Impact

Systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is a catastrophic complication of one of the most common and devastating autoimmune diseases. Once diagnosed, it becomes the leading cause of mortality among this patient population. Screening modalities and risk assessments have been designed and validated by various organizations and societies in order to identify patients early in their disease course and promptly refer them to expert centers for a hemodynamic assessment and formal diagnosis. Moreover, several large multicenter clinical trials have now included patients with SSc-PAH to assess their response to therapy. Despite an improved understanding of the condition and significant advances in supportive and targeted therapy, outcomes have remained far from optimal. Therefore, rigorous phenotyping and search for novel therapies are desperately needed for this devastating condition.

Chronic Thromboembolic Pulmonary Hypertension: the Bedside

PURPOSE OF REVIEW

Chronic thromboembolic pulmonary hypertension (CTEPH), included in group 4 PH, is an uncommon complication of acute pulmonary embolism (PE), in which emboli in the pulmonary vasculature do not resolve but rather form into an organized scar-like obstruction which can result in right ventricular (RV) failure. Here we provide an overview of current diagnosis and management of CTEPH.

RECENT FINDINGS

CTEPH management is complex with treatments that range from surgery, percutaneous interventions, to medical therapies. Current CTEPH medical therapies have largely been repurposed from pulmonary arterial hypertension (PAH). The diagnosis of CTEPH can be challenging, requiring a multimodality approach to differentiate from disease mimics. While these treatments improve symptoms, they may not reverse the underlying pathology of CTEPH.

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.

Pulmonary Embolism: A Practical Guide for the Busy Clinician

Acute pulmonary embolism (PE) is the third most common acute cardiovascular condition, and its prevalence increases over time. D-dimer has a very high negative predictive value, and if normal levels of D-dimer are detected, the diagnosis of PE is very unlikely. The final diagnosis should be confirmed by computed tomographic scan. However, echocardiography is the most available, bedside, low-cost, diagnostic procedure for patients with PE. Risk stratification is of utmost importance and is mainly based on hemodynamic status of the patient. Patients with PE and hemodynamic stability require further risk assessment, based on clinical symptoms, imaging, and circulating biomarkers.

[The achievements of the modern specific therapy of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: focus on the stimulator of soluble guanylate cyclase riociguat]

Currently, treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) is focused on three signaling pathways: the NO pathway, the endothelin pathway, and the prostacyclin pathway. Riociguat is the only representative of stimulators of the soluble guanylate cyclase (sGC) class that is approved for the treatment of PAH and inoperable and persistent/recurrent CTEPH. The review presents data from clinical trials showing a positive effect of riociguat on the functional and hemodynamic profile of patients with PAH and CTEPH. In recent years there has been much discussion about the possibility of optimizing therapy by switching to drugs that affect a single pathogenesis target. Thus, sGC stimulants have obvious advantages over phosphodiesterase type 5 (PDE-5) inhibitors, including the ability of riociguat to exert pharmacological effects (due to a NO-independent mechanism of action) even in conditions of reduced NO production. Switching from PDE-5 to riociguat may be safe and appropriate, according to clinical trials presented in the review. In accordance with the guidelines for the diagnosis and treatment of pulmonary hypertension of the Eurasian Association of cardiologists from 2019, this strategy is approved when PDE5 therapy is ineffective in patients with PAH FC III (WHO).

[The soluble guanylate cyclase stimulator riociguat is the first-line therapy for chronic thromboembolic pulmonary hypertension patients]

Chronic thromboembolic pulmonary hypertension (CTEPH) is a precapillary type of pulmonary hypertension with chronic obstruction of large and medium branches of pulmonary arteries along with secondary alterations in pulmonary microcirculation, which cause progressive increases in pulmonary vascular resistance and pulmonary arterial pressure and ensuing severe right heart dysfunction and heart failure. Pulmonary thromboendarterectomy (PTE) is the treatment of choice for CTEPH; however, this procedure is available not for all patients. Although the surgery performed in the conditions of centers with advanced experience generally shows good results, up to 40% of patients are technically inoperable or PTE is associated with a high risk of complications. At present, riociguat, the only officially approved drug from the class of soluble guanylate cyclase stimulators, is considered as a first-line treatment for inoperable and residual forms of STEPH. Introduction of riociguat to clinical practice can be called a real breakthrough in the treatment of patients with STEPH who cannot undergo PTE or those with relapse or persistent STEPH after the surgery.

One-Year Echocardiographic, Functional, and Quality of Life Outcomes After Ultrasound-Facilitated Catheter-Based Fibrinolysis for Pulmonary Embolism

Accelerated tPA (tissue-type plasminogen activator) dosing regimens for ultrasound-facilitated, catheter-directed fibrinolysis improve short-term computed tomographic-measured right ventricular (RV)-to-left ventricular diameter ratio in massive and submassive pulmonary embolism. The impact on RV remodeling, functional status, and quality of life over the long-term remains unclear.

Association of Mild Echocardiographic Pulmonary Hypertension With Mortality and Right Ventricular Function

Importance

Current guidelines recommend evaluation for echocardiographically estimated right ventricular systolic pressure (RVSP) greater than 40 mm Hg; however, this threshold does not capture all patients at risk.

Objectives

To determine if mild echocardiographic pulmonary hypertension (ePH) is associated with reduced right ventricular (RV) function and increased risk of mortality.

Design, Setting, and Participants

In this cohort study, electronic health record data of patients who were referred for echocardiography at Vanderbilt University Medical Center, Nashville, Tennessee, from March 1997 to February 2014 and had recorded estimates of RVSP values were studied. Data were analyzed from February 2017 to May 2019.

Exposures

Mild ePH was defined as an RVSP value of 33 to 39 mm Hg. Right ventricular function was assessed using tricuspid annular plane systolic excursion (TAPSE), and RV-pulmonary arterial coupling was measured using the ratio of TAPSE to RVSP.

Main Outcomes and Measures

Associations of mild ePH with mortality adjusted for relevant covariates were examined using Cox proportional hazard models with restricted cubic splines.

Results

Of the 47 784 included patients, 26 758 of 47 771 (56.0%) were female and 6040 of 44 763 (13.5%) were black, and the mean (SD) age was 59 (18) years. Patients with mild ePH had worse RV function compared with those with no ePH (mean [SD] TAPSE, 2.0 [0.6] cm vs 2.2 [0.5] cm; P < .001) and nearly double the prevalence of RV dysfunction (32.6% [92 of 282] vs 16.7% [170 of 1015]; P < .001). Compared with patients with RVSP less than 33 mm Hg, those with mild ePH also had reduced RV-pulmonary arterial coupling (mean [SD] ratio of TAPSE to RVSP, 0.55 [0.18] mm/mm Hg vs 0.93 [0.39] mm/mm Hg; P < .001). An increase in adjusted mortality began at an RVSP value of 27 mm Hg (hazard ratio, 1.32; 95% CI, 1.02-1.70). Female sex was associated with increased mortality risk at any given RVSP value.

Conclusions and Relevance

Mild ePH was associated with RV dysfunction and worse RV-pulmonary arterial coupling in a clinical population seeking care. Future studies are needed to identify patients with mild ePH who are susceptible to adverse outcomes.

Evolving spectrum of treatment for CTEPH

PURPOSE OF REVIEW

The present review provides an update on treatment of chronic thromboembolic pulmonary hypertension (CTEPH), a rare form of pulmonary hypertension characterized by precapillary pulmonary hemodynamic parameters with chronic thrombotic occlusion of the pulmonary vasculature.

RECENT FINDINGS

Pulmonary thromboendarectomy (PTE) remains the recommended treatment for patients with surgically accessible disease. Recent data suggest that patients preoperatively bridged with medical therapy may have improved outcomes but further research is needed. Riociguat improves hemodynamics, right ventricular function, quality of life, and functional capacity and is the drug of choice for patients with inoperable/persistent disease. Recently published data suggest that endothelin receptor blockers and treprostinil may also have a role in medical management of this patient population. A growing body of evidence indicates that in experienced centers balloon pulmonary angioplasty (BPA) may be a well tolerated and effective adjunct to pharmacological treatment for patients with inoperable disease affecting subsegmental vasculature.

SUMMARY

Untreated CTEPH carries significant morbidity and mortality. Recent publications provide a wealth of data on safety and efficacy of BPA for inoperable subsegmental disease, but its precise fit in the treatment algorithm, both pharmacological and procedural, requires further investigation. PTE remains the procedure of choice for surgically accessible disease.

Treatment of pulmonary hypertension with riociguat: a review of current evidence and future perspectives

INTRODUCTION

Pulmonary arterial hypertension (PAH) is still a chronic disorder characterized by high morbidity and mortality. Chronic thromboembolic pulmonary hypertension (CTEPH) is another form of pulmonary hypertension (PH) for which pulmonary endarterectomy (PEA) is the treatment of choice. However, not all patients are operable, while PH is often recurrent or persistent. Thus, for both disorders novel treatment options are urgently needed.

AREAS COVERED

This review describes the mechanism of action of riociguat, a soluble guanylate cyclase (sGC) stimulator, with a dual mode of action. The most relevant publications are presented regarding the efficacy of riociguat in PAH and CTEPH, and also data regarding its potential effect on other forms of PH.

EXPERT OPINION

Riociguat is a first-in-class drug approved for the treatment of PAH as a monotherapy or added to endothelin-receptor antagonists as a sequential combination therapy, and for the treatment of inoperable CTEPH or persistent/recurrent PH after PEA. As it can stimulate sGC independently of NO, it could be beneficial in PAH patients with inadequate response to phosphodiesterase 5 inhibitors (PDE5i). Future studies are needed to evaluate whether drug switching is beneficial in PAH and which baseline markers could guide the optimal initial treatment selection.

Soluble Guanylate Cyclase Stimulators for Chronic Thromboembolic Pulmonary Hypertension Patients Treatment: New Data

This narrative review describes and appraises some relatively new studies investigating the efficacy and safety profile of soluble guanylate cyclase stimulator riociguat in patients suffering from pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). It has been a while since the publication date of pivotal CHEST-1 trial in 2013. New studies available complement existing evidence, expound on specific questions and open new frontiers for CTEPH investigations going forward. In this paper authors attempted to present data from post-hocanalysis of the CHEST-1 study and real-world data on riociguat treatment, confirming the positive effect of the drug on hemodynamic parameters of the pulmonary circulation and the functional status of patients. This effect was shown previously in large randomized trials. The extremely important positive effect of riociguat demonstrated both in the group of inoperable patients with CTEPH and in patients with residual pulmonary hypertension after pulmonary thrombendarterectomy. Of great interest are the presented some authors results of reverse remodelling of the right heart chambers during riociguat therapy in CTEPH patients, including using unique imaging methods (magnetic resonance imaging and positron emission tomography) to evaluate targeted medicinal therapy in terms of right heart remodelling. The safety profile of the drug was analyzed in the long-term post-registration international, multicenter, prospective, observational study EXPERT (NCT02092818), which confirmed the good tolerability and safety of riociguat therapy in PAH and CTEPH patients.

Minimally Invasive Mechanical Circulatory Support Through the Perioperative Pulmonary Thromboendarterectomy Period: A Case Report

A 64-year-old man being evaluated for pulmonary thromboendarterectomy (PTE) preoperatively experienced pulseless electrical activity secondary to right ventricular failure while undergoing bronchoscopy. After return of spontaneous circulation, a percutaneous right ventricular assist device (RVAD) was placed through the right internal jugular vein. He continued on right ventricular support with demonstration of right ventricular recovery over the following 8 days, and subsequently underwent PTE for treatment of his primary condition. He recovered and was weaned from his RVAD support uneventfully. The need for RVAD support has traditionally been a contraindication for PTE; however, circulatory assist devices have been used as a salvage procedure for right-heart failure after PTE. This case highlights the potential for percutaneous mechanical circulatory support in treating severe perioperative right ventricular dysfunction, and to facilitate successful recovery in patients undergoing PTE.

Management of Pulmonary Arterial Hypertension in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a rare and complex immune-mediated connective tissue disease characterized by multi-organ fibrosis and dysfunction. Systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is a leading cause of death in this population. Pulmonary arterial hypertension (PAH) can coexist with other forms of pulmonary hypertension in SSc, including pulmonary hypertension related to left heart disease, interstitial lung disease, chronic thromboembolism and pulmonary venous occlusive disease, which further complicates diagnosis and management. Available pulmonary arterial hypertension therapies target the nitric oxide, endothelin and prostacyclin pathways. These therapies have been studied in SSc-PAH in addition to idiopathic PAH, often with different treatment responses. In this article, we discuss the management as well as the treatment options for patients with SSc-PAH.

Right heart failure in pulmonary hypertension: Diagnosis and new perspectives on vascular and direct right ventricular treatment

Adaptation of right ventricular (RV) function to increased afterload-known as RV-arterial coupling-is a key determinant of prognosis in pulmonary hypertension. However, measurement of RV-arterial coupling is a complex, invasive process involving analysis of the RV pressure-volume relationship during preload reduction over multiple cardiac cycles. Simplified methods have therefore been proposed, including echocardiographic and cardiac MRI approaches. This review describes the available methods for assessment of RV function and RV-arterial coupling and the effects of pharmacotherapy on these variables. Overall, pharmacotherapies for pulmonary hypertension have shown beneficial effects on various measures of RV function, but it is often unclear if these are direct RV effects or indirect results of afterload reduction. Studies of the effects of pharmacotherapies on RV-arterial coupling are limited and mostly restricted to experimental models. Simplified methods to assess RV-arterial coupling should be validated and incorporated into routine clinical follow-up and future clinical trials. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

Improvements of right ventricular function and hemodynamics after balloon pulmonary angioplasty in patients with chronic thromboembolic pulmonary hypertension

PURPOSE

Right ventricular (RV) function is an important factor in the prognosis of chronic thromboembolic pulmonary hypertension (CTEPH) in patients. In our study, we aimed to evaluate the timing and magnitude of regional RV function before and after balloon pulmonary angioplasty (BPA) using speckle tracking echocardiography (STE) and their relation to clinical and hemodynamic parameters in patients with CTEPH.

MATERIAL AND METHOD

We enrolled 20 CTEPH patients and 19 healthy subjects in our study. Enrolled patients underwent echocardiography, right heart catheterization (RHC), and 6-minute walk distance (6MWD) test at baseline and after the BPA.

RESULTS

In hemodynamic RHC measurements and clinical evaluations, mean pulmonary artery pressure (median: 53.5 mm Hg vs 37.0 mm Hg, P = .001) and pulmonary vascular resistance (median: 12 Wood units [WU] vs 7 WU, P = .001) and pro-brain natriuretic peptide level decreased and 6MWD increased after BPA sessions. There was no statistically significant difference between before and after the BPA sessions in conventional echocardiographic measurements. In STE analysis, the electromechanical delay (EMD) between RV free wall (RVF) and LV lateral wall (LVL) (median: 65 ms vs 47.5 ms, P = .01) and RV peak systolic strain dispersion index (52 ms vs 29 ms, P = .001) were higher in patients with CTEPH than healthy controls before the BPA. Both these parameters decreased significantly after BPA.

CONCLUSION

Chronic thromboembolic pulmonary hypertension was associated with RV electromechanical delay and dispersion based on the STE analysis. Balloon pulmonary angioplasty might have an important impact on the improvement of both RV function and hemodynamics.

A focus on riociguat in the treatment of pulmonary arterial hypertension

Current treatment of pulmonary arterial hypertension (PAH) targets three signalling pathways: the nitric oxide (NO) pathway, the endothelin pathway and the prostacyclin pathway. Riociguat is a soluble guanylate cyclase stimulator, acting via the NO pathway in a new way: unlike other common drugs targeting this pathway (eg tadalafil and sildenafil), riociguat acts independently of endogenous NO. This MiniReview focuses on PAH treatment with riociguat and on its advantages and disadvantages compared with other drugs targeting the NO pathway. In the PATENT-1 trial (NCT00810693), riociguat improved significantly the 6-minute walking distance in patients suffering from PAH, with a mean difference (MD) of 36 m compared with a placebo group. The results are comparable to those found for its competitors tadalafil (MD of 33 m) and sildenafil (MD of 50 m) in the PHIRST-1 trial (NCT00125918) and the SUPER-1 trial (NCT00644605). No obvious advantages were found regarding pharmacokinetic features and adverse events. In the RESPITE study (NCT02007629), patients with PAH with insufficient response to treatment with tadalafil or sildenafil were switched to riociguat. These results indicate that riociguat might be superior regarding efficacy to PDE-5 inhibitors in a patient group, where endogenous NO production might be insufficient. This finding was further examined in the REPLACE study (NCT02891850). Moreover, riociguat has shown promising anti-proliferative, anti-inflammatory and anti-fibrotic effects in animal models. Further investigations are needed to determine whether this applies also to human beings. Taken together, riociguat induces vasodilation of the pulmonary arteries and leads to an improvement in the ability to carry out physical activity.