Cerebrovascular Effects of Sildenafil in Small Vessel Disease: The OxHARP Trial.

BACKGROUND: Vascular cognitive impairment due to cerebral small vessel disease is associated with cerebral pulsatility, white matter hypoperfusion, and reduced cerebrovascular reactivity (CVR), and is potentially improved by endothelium-targeted drugs such as cilostazol. Whether sildenafil, a phosphodiesterase-5 inhibitor, improves cerebrovascular dysfunction is unknown. METHODS: OxHARP trial (Oxford Haemodynamic Adaptation to Reduce Pulsatility) was a double-blind, randomized, placebo-controlled, 3-way crossover trial after nonembolic cerebrovascular events with mild-moderate white matter hyperintensities (WMH), the most prevalent manifestation of cerebral small vessel disease. The primary outcome assessed the superiority of 3 weeks of sildenafil 50 mg thrice daily versus placebo (mixed-effect linear models) on middle cerebral artery pulsatility, derived from peak systolic and end-diastolic velocities (transcranial ultrasound), with noninferiority to cilostazol 100 mg twice daily. Secondary end points included the following: cerebrovascular reactivity during inhalation of air, 4% and 6% CO2 on transcranial ultrasound (transcranial ultrasound-CVR); blood oxygen-level dependent-magnetic resonance imaging within WMH (CVR-WMH) and normal-appearing white matter (CVR-normal-appearing white matter); cerebral perfusion by arterial spin labeling (magnetic resonance imaging pseudocontinuous arterial spin labeling); and resistance by cerebrovascular conductance. Adverse effects were compared by Cochran Q. RESULTS: In 65/75 (87%) patients (median, 70 years;79% male) with valid primary outcome data, cerebral pulsatility was unchanged on sildenafil versus placebo (0.02, -0.01 to 0.05; P=0.18), or versus cilostazol (-0.01, -0.04 to 0.02; P=0.36), despite increased blood flow (∆ peak systolic velocity, 6.3 cm/s, 3.5-9.07; P<0.001; ∆ end-diastolic velocity, 1.98, 0.66-3.29; P=0.004). Secondary outcomes improved on sildenafil versus placebo for CVR-transcranial ultrasound (0.83 cm/s per mm Hg, 0.23-1.42; P=0.007), CVR-WMH (0.07, 0-0.14; P=0.043), CVR-normal-appearing white matter (0.06, 0.00-0.12; P=0.048), perfusion (WMH: 1.82 mL/100 g per minutes, 0.5-3.15; P=0.008; and normal-appearing white matter, 2.12, 0.66-3.6; P=0.006) and cerebrovascular resistance (sildenafil-placebo: 0.08, 0.05-0.10; P=4.9×10-8; cilostazol-placebo, 0.06, 0.03-0.09; P=5.1×10-5). Both drugs increased headaches (P=1.1×10-4), while cilostazol increased moderate-severe diarrhea (P=0.013). CONCLUSIONS: Sildenafil did not reduce pulsatility but increased cerebrovascular reactivity and perfusion. Sildenafil merits further study to determine whether it prevents the clinical sequelae of small vessel disease. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03855332.

Systematic pulmonary embolism follow-up increases diagnostic rates of chronic thromboembolic pulmonary hypertension and identifies less severe disease: results from the ASPIRE Registry.

BACKGROUND: Diagnostic rates and risk factors for the subsequent development of chronic thromboembolic pulmonary hypertension (CTEPH) following pulmonary embolism (PE) are not well defined. METHODS: Over a 10-year period (2010-2020), consecutive patients attending a PE follow-up clinic in Sheffield, UK (population 554 600) and all patients diagnosed with CTEPH at a pulmonary hypertension (PH) referral centre in Sheffield (referral population estimated 15-20 million) were included. RESULTS: Of 1956 patients attending the Sheffield PE clinic 3 months following a diagnosis of acute PE, 41 were diagnosed with CTEPH with a cumulative incidence of 2.10%, with 1.89% diagnosed within 2 years. Of 809 patients presenting with pulmonary hypertension (PH) and diagnosed with CTEPH, 32 were Sheffield residents and 777 were non-Sheffield residents. Patients diagnosed with CTEPH at the PE follow-up clinic had shorter symptom duration (p<0.01), better exercise capacity (p<0.05) and less severe pulmonary haemodynamics (p<0.01) compared with patients referred with suspected PH. Patients with no major transient risk factors present at the time of acute PE had a significantly higher risk of CTEPH compared with patients with major transient risk factors (OR 3.6, 95% CI 1.11-11.91; p=0.03). The presence of three computed tomography (CT) features of PH in combination with two or more out of four features of chronic thromboembolic pulmonary disease at the index PE was found in 19% of patients who developed CTEPH and in 0% of patients who did not. Diagnostic rates and pulmonary endarterectomy (PEA) rates were higher at 13.2 and 3.6 per million per year, respectively, for Sheffield residents compared with 3.9-5.2 and 1.7-2.3 per million per year, respectively, for non-Sheffield residents. CONCLUSIONS: In the real-world setting a dedicated PE follow-up pathway identifies patients with less severe CTEPH and increases population-based CTEPH diagnostic and PEA rates. At the time of acute PE diagnosis the absence of major transient risk factors, CT features of PH and chronic thromboembolism are risk factors for a subsequent diagnosis of CTEPH.

Anatomical characterization of pulmonary artery and implications to pulmonary artery pressure monitor implantation.

In patients with heart failure, guideline directed medical therapy improves outcomes and requires close patient monitoring. Pulmonary artery pressure monitors permit remote assessment of cardiopulmonary haemodynamics and facilitate early intervention that has been shown to decrease heart failure hospitalization. Pressure sensors implanted in the pulmonary vasculature are stabilized through passive or active interaction with the anatomy and communicate with an external reader to relay invasively measured pressure by radiofrequency. A body mass index > 35 kg/m2 and chest circumference > 165 cm prevent use due to poor communication. Pulmonary vasculature anatomy is variable between patients and the pulmonary artery size, angulation of vessels and depth of sensor location from the chest wall in heart failure patients who may be candidates for pressure sensors remains largely unexamined. The present study analyses the size, angulation, and depth of the pulmonary artery at the position of implantation of two pulmonary artery pressure sensors: the CardioMEMS sensor typically implanted in the left pulmonary artery and the Cordella sensor implanted in the right pulmonary artery. Thirty-four computed tomography pulmonary angiograms from patients with heart failure were analysed using the MIMICS software. Distance from the bifurcation of the pulmonary artery to the implant site was shorter for the right pulmonary artery (4.55 ± 0.64 cm vs. 7.4 ± 1.3 cm) and vessel diameter at the implant site was larger (17.15 ± 2.87 mm vs. 11.83 ± 2.30 mm). Link distance (length of the communication path between sensor and reader) was shorter for the left pulmonary artery (9.40 ± 1.43 mm vs. 12.54 ± 1.37 mm). Therefore, the detailed analysis of pulmonary arterial anatomy using computed tomography pulmonary angiograms may alter the choice of implant location to reduce the risk of sensor migration and improve readability by minimizing sensor-to-reader link distance.

Non-invasive detection of severe PH in lung disease using magnetic resonance imaging.

Introduction: Severe pulmonary hypertension (mean pulmonary artery pressure ≥35 mmHg) in chronic lung disease (PH-CLD) is associated with high mortality and morbidity. Data suggesting potential response to vasodilator therapy in patients with PH-CLD is emerging. The current diagnostic strategy utilises transthoracic Echocardiography (TTE), which can be technically challenging in some patients with advanced CLD. The aim of this study was to evaluate the diagnostic role of MRI models to diagnose severe PH in CLD. Methods: 167 patients with CLD referred for suspected PH who underwent baseline cardiac MRI, pulmonary function tests and right heart catheterisation were identified. In a derivation cohort (n = 67) a bi-logistic regression model was developed to identify severe PH and compared to a previously published multiparameter model (Whitfield model), which is based on interventricular septal angle, ventricular mass index and diastolic pulmonary artery area. The model was evaluated in a test cohort. Results: The CLD-PH MRI model [= (-13.104) + (13.059 * VMI)-(0.237 * PA RAC) + (0.083 * Systolic Septal Angle)], had high accuracy in the test cohort (area under the ROC curve (0.91) (p < 0.0001), sensitivity 92.3%, specificity 70.2%, PPV 77.4%, and NPV 89.2%. The Whitfield model also had high accuracy in the test cohort (area under the ROC curve (0.92) (p < 0.0001), sensitivity 80.8%, specificity 87.2%, PPV 87.5%, and NPV 80.4%. Conclusion: The CLD-PH MRI model and Whitfield model have high accuracy to detect severe PH in CLD, and have strong prognostic value.

Ambulatory haemodynamic-guided management reduces heart failure hospitalizations in a multicentre European heart failure cohort.

AIMS: To investigate the outcomes and associated costs of haemodynamic-guided heart failure (HF) management with a pulmonary artery pressure (PAP) sensor in a multicentre European cohort. METHODS AND RESULTS: Data from all consecutive patients receiving a PAP sensor in Ziekenhuis Oost-Limburg, University Hospital Zurich and Sheffield Teaching Hospitals NHS Foundation Trust before January 2021 were collected. Medication changes, total number of HF hospitalizations and HF related health care costs (composed of HF hospitalizations, outpatient cardiology visits and monitoring costs) were compared between the pre-implantation and post-implantation period at 3, 6, and 12 months. PAP evolution post-implantation were grouped according to baseline mPAP ≥25 mmHg versus <25 mmHg and changes from baseline were analyzed via an area under the curve (AUC) analysis. A total of 48 patients received a PAP sensor (29 CardioMEMS and 19 Cordella devices) with a median follow-up of 19 (13-30) months. Mean age was 71 ± 10 years, 25.0% were female, 68.8% had a left ventricular ejection fraction < 50%, median NT-proBNP was 1801 (827-4503) pg/mL, and 89.6% were in NYHA class III. The number of diuretic therapy changes were non-significantly increased after 3 months (49 vs. 82; P = 0.284) and 6 months (82 vs. 127; P = 0.093) with a significant increase noted after 12 months (118 vs. 195; P = 0.005). The mPAP AUC decreased by -1418 mmHg-days for patients with a baseline mean PAP ≥ 25 mmHg. The number of HF hospitalizations was reduced for all patients after 6 (34 vs. 17; P = 0.014) and 12 months (48 vs. 29; P = 0.032). HF related health care costs were reduced from € 6286 to € 3761 at 6 months (P = 0.012) and from € 8960 to € 6167 at 12 months (P = 0.032). CONCLUSION: Haemodynamic-guided HF management reduces HF hospitalizations and HF related health care costs in selected HF patients amongst different European health care systems.

Validation of Artificial Intelligence Cardiac MRI Measurements: Relationship to Heart Catheterization and Mortality Prediction.

Background Cardiac MRI measurements have diagnostic and prognostic value in the evaluation of cardiopulmonary disease. Artificial intelligence approaches to automate cardiac MRI segmentation are emerging but require clinical testing. Purpose To develop and evaluate a deep learning tool for quantitative evaluation of cardiac MRI functional studies and assess its use for prognosis in patients suspected of having pulmonary hypertension. Materials and Methods A retrospective multicenter and multivendor data set was used to develop a deep learning-based cardiac MRI contouring model using a cohort of patients suspected of having cardiopulmonary disease from multiple pathologic causes. Correlation with same-day right heart catheterization (RHC) and scan-rescan repeatability was assessed in prospectively recruited participants. Prognostic impact was assessed using Cox proportional hazard regression analysis of 3487 patients from the ASPIRE (Assessing the Severity of Pulmonary Hypertension In a Pulmonary Hypertension Referral Centre) registry, including a subset of 920 patients with pulmonary arterial hypertension. The generalizability of the automatic assessment was evaluated in 40 multivendor studies from 32 centers. Results The training data set included 539 patients (mean age, 54 years ± 20 [SD]; 315 women). Automatic cardiac MRI measurements were better correlated with RHC parameters than were manual measurements, including left ventricular stroke volume (r = 0.72 vs 0.68; P = .03). Interstudy repeatability of cardiac MRI measurements was high for all automatic measurements (intraclass correlation coefficient range, 0.79-0.99) and similarly repeatable to manual measurements (all paired t test P > .05). Automated right ventricle and left ventricle cardiac MRI measurements were associated with mortality in patients suspected of having pulmonary hypertension. Conclusion An automatic cardiac MRI measurement approach was developed and tested in a large cohort of patients, including a broad spectrum of right ventricular and left ventricular conditions, with internal and external testing. Fully automatic cardiac MRI assessment correlated strongly with invasive hemodynamics, had prognostic value, were highly repeatable, and showed excellent generalizability. Clinical trial registration no. NCT03841344 Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Ambale-Venkatesh and Lima in this issue. An earlier incorrect version appeared online. This article was corrected on June 27, 2022.

Right ventricular remodelling in pulmonary arterial hypertension predicts treatment response.

OBJECTIVES: To determine the prognostic value of patterns of right ventricular adaptation in patients with pulmonary arterial hypertension (PAH), assessed using cardiac magnetic resonance (CMR) imaging at baseline and follow-up. METHODS: Patients attending the Sheffield Pulmonary Vascular Disease Unit with suspected pulmonary hypertension were recruited into the ASPIRE (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral Centre) Registry. With exclusion of congenital heart disease, consecutive patients with PAH were followed up until the date of census or death. Right ventricular end-systolic volume index adjusted for age and sex and ventricular mass index were used to categorise patients into four different volume/mass groups: low-volume-low-mass, low-volume-high-mass, high-volume-low-mass and high-volume-high-mass. The prognostic value of the groups was assessed with one-way analysis of variance and Kaplan-Meier plots. Transition of the groups was studied. RESULTS: A total of 505 patients with PAH were identified, 239 (47.3%) of whom have died at follow-up (median 4.85 years, IQR 4.05). The mean age of the patients was 59±16 and 161 (32.7%) were male. Low-volume-low-mass was associated with CMR and right heart catheterisation metrics predictive of improved prognosis. There were 124 patients who underwent follow-up CMR (median 1.11 years, IQR 0.78). At both baseline and follow-up, the high-volume-low-mass group had worse prognosis than the low-volume-low-mass group (p<0.001). With PAH therapy, 73.5% of low-volume-low-mass patients remained in this group, whereas only 17.4% of high-volume-low-mass patients transitioned into low-volume-low-mass. CONCLUSIONS: Right ventricular adaptation assessed using CMR has prognostic value in patients with PAH. Patients with maladaptive remodelling (high-volume-low-mass) are at high risk of treatment failure.

Severe pulmonary hypertension associated with lung disease is characterised by a loss of small pulmonary vessels on quantitative computed tomography.

Background: Pulmonary hypertension (PH) in patients with chronic lung disease (CLD) predicts reduced functional status, clinical worsening and increased mortality, with patients with severe PH-CLD (≥35 mmHg) having a significantly worse prognosis than mild to moderate PH-CLD (21-34 mmHg). The aim of this cross-sectional study was to assess the association between computed tomography (CT)-derived quantitative pulmonary vessel volume, PH severity and disease aetiology in CLD. Methods: Treatment-naïve patients with CLD who underwent CT pulmonary angiography, lung function testing and right heart catheterisation were identified from the ASPIRE registry between October 2012 and July 2018. Quantitative assessments of total pulmonary vessel and small pulmonary vessel volume were performed. Results: 90 patients had PH-CLD including 44 associated with COPD/emphysema and 46 with interstitial lung disease (ILD). Patients with severe PH-CLD (n=40) had lower small pulmonary vessel volume compared to patients with mild to moderate PH-CLD (n=50). Patients with PH-ILD had significantly reduced small pulmonary blood vessel volume, compared to PH-COPD/emphysema. Higher mortality was identified in patients with lower small pulmonary vessel volume. Conclusion: Patients with severe PH-CLD, regardless of aetiology, have lower small pulmonary vessel volume compared to patients with mild-moderate PH-CLD, and this is associated with a higher mortality. Whether pulmonary vessel changes quantified by CT are a marker of remodelling of the distal pulmonary vasculature requires further study.

Imaging and Risk Stratification in Pulmonary Arterial Hypertension: Time to Include Right Ventricular Assessment.

Background: Current European Society of Cardiology and European Respiratory Society guidelines recommend regular risk stratification with an aim of treating patients with pulmonary arterial hypertension (PAH) to improve or maintain low-risk status (<5% 1-year mortality). Methods: Consecutive patients with PAH who underwent cardiac magnetic resonance imaging (cMRI) were identified from the Assessing the Spectrum of Pulmonary hypertension Identified at a Referral centre (ASPIRE) registry. Kaplan-Meier survival curves, locally weighted scatterplot smoothing regression and multi-variable logistic regression analysis were performed. Results: In 311 consecutive, treatment-naïve patients with PAH undergoing cMRI including 121 undergoing follow-up cMRI, measures of right ventricular (RV) function including right ventricular ejection fraction (RVEF) and RV end systolic volume and right atrial (RA) area had prognostic value. However, only RV metrics were able to identify a low-risk status. Age (p < 0.01) and RVEF (p < 0.01) but not RA area were independent predictors of 1-year mortality. Conclusion: This study highlights the need for guidelines to include measures of RV function rather than RA area alone to aid the risk stratification of patients with PAH.

Machine learning cardiac-MRI features predict mortality in newly diagnosed pulmonary arterial hypertension.

Aims: Pulmonary arterial hypertension (PAH) is a rare but serious disease associated with high mortality if left untreated. This study aims to assess the prognostic cardiac magnetic resonance (CMR) features in PAH using machine learning. Methods and results: Seven hundred and twenty-three consecutive treatment-naive PAH patients were identified from the ASPIRE registry; 516 were included in the training, and 207 in the validation cohort. A multilinear principal component analysis (MPCA)-based machine learning approach was used to extract mortality and survival features throughout the cardiac cycle. The features were overlaid on the original imaging using thresholding and clustering of high- and low-risk of mortality prediction values. The 1-year mortality rate in the validation cohort was 10%. Univariable Cox regression analysis of the combined short-axis and four-chamber MPCA-based predictions was statistically significant (hazard ratios: 2.1, 95% CI: 1.3, 3.4, c-index = 0.70, P = 0.002). The MPCA features improved the 1-year mortality prediction of REVEAL from c-index = 0.71 to 0.76 (P ≤ 0.001). Abnormalities in the end-systolic interventricular septum and end-diastolic left ventricle indicated the highest risk of mortality. Conclusion: The MPCA-based machine learning is an explainable time-resolved approach that allows visualization of prognostic cardiac features throughout the cardiac cycle at the population level, making this approach transparent and clinically interpretable. In addition, the added prognostic value over the REVEAL risk score and CMR volumetric measurements allows for a more accurate prediction of 1-year mortality risk in PAH.

The Impact of Virtual Fractional Flow Reserve and Virtual Coronary Intervention on Treatment Decisions in the Cardiac Catheter Laboratory.

BACKGROUND: Using fractional flow reserve (FFR) to guide percutaneous coronary intervention for patients with coronary artery disease (CAD) improves clinical decision making but remains underused. Virtual FFR (vFFR), computed from angiographic images, permits physiologic assessment without a pressure wire and can be extended to virtual coronary intervention (VCI) to facilitate treatment planning. This study investigated the effect of adding vFFR and VCI to angiography in patient assessment and management. METHODS: Two cardiologists independently reviewed clinical data and angiograms of 50 patients undergoing invasive management of coronary syndromes, and their management plans were recorded. The vFFRs were computed and disclosed, and the cardiologists submitted revised plans. Then, using VCI, the physiologic results of various interventional strategies were shown and further revision was invited. RESULTS: Disclosure of vFFR led to a change in strategy in 27%. VCI led to a change in stent size in 48%. Disclosure of vFFR and VCI resulted in an increase in operator confidence in their decision. Twelve cases were reviewed by 6 additional cardiologists. There was limited agreement in the management plans between cardiologists based on either angiography (kappa = 0.31) or vFFR (kappa = 0.39). CONCLUSIONS: vFFR has the potential to alter decision making, and VCI can guide stent sizing. However, variability in management strategy remains considerable between operators, even when presented with the same anatomic and physiologic data.

Prolonged enoxaparin therapy compared with standard-of-care antithrombotic therapy in opiate-treated patients undergoing primary percutaneous coronary intervention.

A novel enoxaparin regimen consisting of intra-arterial bolus (0.75 mg/kg) followed by intravenous infusion (0.75 mg/kg/6 hours) has been developed as a possible solution to the delayed absorption of oral P2Y12 inhibitors in opiate-treated ST-elevation myocardial infarction (STEMI) patients undergoing primary angioplasty. We aimed to study the feasibility of this regimen as an alternative to standard-of-care treatment (SOC) with unfractionated heparin ± glycoprotein IIb/IIIa antagonist (GPI). One hundred opiate-treated patients presenting with STEMI and accepted for primary angioplasty were randomized (1:1) to either enoxaparin or SOC. Fifty patients were allocated enoxaparin (median age 61, 40% females) and 49 allocated SOC (median age 62, 22% females). One developed stroke before angiography and was withdrawn. One SOC patient had a gastrointestinal bleed resulting in 1 g drop in hemoglobin and early cessation of GPI infusion. Two enoxaparin patients had transient minor bleeding: one transient gingival bleed and one episode of coffee ground vomit with no hemoglobin drop or hemodynamic instability. Two SOC and no enoxaparin group patients had acute stent thrombosis. These preliminary data support further study of this novel 6-hour enoxaparin regimen in opiate-treated PPCI patients.

Maximal Exercise Testing Using the Incremental Shuttle Walking Test Can Be Used to Risk-Stratify Patients with Pulmonary Arterial Hypertension.

Rationale: Exercise capacity predicts mortality in pulmonary arterial hypertension (PAH), but limited data exist on the routine use of maximal exercise testing.Objectives: This study evaluates a simple-to-perform maximal test (the incremental shuttle walking test) and its use in risk stratification in PAH.Methods: Consecutive patients with pulmonary hypertension were identified from the ASPIRE (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral centre) registry (2001-2018). Thresholds for levels of risk were identified at baseline and tested at follow-up, and their incorporation into current risk stratification approaches was assessed.Results: Of 4,524 treatment-naive patients with pulmonary hypertension who underwent maximal exercise testing, 1,847 patients had PAH. A stepwise reduction in 1-year mortality was seen between levels 1 (≤30 m; 32% mortality) and 7 (340-420 m; 1% mortality) with no mortality for levels 8-12 (≥430 m) in idiopathic and connective tissue disease-related PAH. Thresholds derived at baseline of ≤180 m (>10%; high risk), 190-330 m (5-10%; intermediate risk), and ≥340 m (<5%; low risk of 1-yr mortality) were applied at follow-up and also accurately identified levels of risk. Thresholds were incorporated into the REVEAL (Registry to Evaluate Early and Long-Term Pulmonary Arterial Hypertension Disease Management) 2.0 risk score calculator and French low-risk approach to risk stratification, and distinct categories of risk remained.Conclusions: We have demonstrated that maximal exercise testing in PAH stratifies mortality risk at baseline and follow-up. This study highlights the potential value of the incremental shuttle walking test as an alternative to the 6-minute walking test, combining some of the advantages of maximal exercise testing and maintaining the simplicity of a simple-to-perform field test.

A current and future outlook on upcoming technologies in remote monitoring of patients with heart failure.

Heart failure is a major health and economic challenge in both developing and developed countries. Despite advances in pharmacological and device therapies for patients with a reduced left ventricular ejection fraction (LVEF) and heart failure, their quality of life and exercise capacity are often persistently impaired, morbidity and mortality remain high and the health economic and societal costs are considerable. For patients with heart failure and preserved LVEF, diuretic management has an essential role for controlling congestion and symptoms, even if no intervention has convincingly shown to reduce morbidity or mortality. Remote monitoring might improve care delivery and clinical outcomes for patients regardless of LVEF. A great variety of innovative remote monitoring technologies and algorithms are being introduced, including patient self-managed testing, wearable devices, technologies either integrated into established clinically indicated therapeutic devices, such as pacemakers and defibrillators, or as stand-alone are in development providing the promise of further improvements in service delivery and clinical outcomes. In this article, we will discuss unmet needs in the management of patients with heart failure, how remote monitoring might contribute to future solutions, and provide an overview of current and novel remote monitoring technologies.

Role of biomarkers in evaluation, treatment and clinical studies of pulmonary arterial hypertension.

Pulmonary arterial hypertension is a complex disease resulting from the interplay of myriad biological and environmental processes that lead to remodeling of the pulmonary vasculature with consequent pulmonary hypertension. Despite currently available therapies, there remains significant morbidity and mortality in this disease. There is great interest in identifying and applying biomarkers to help diagnose patients with pulmonary arterial hypertension, inform prognosis, guide therapy, and serve as surrogate endpoints. An extensive literature on potential biomarker candidates is available, but barriers to the implementation of biomarkers for clinical use in pulmonary arterial hypertension are substantial. Various omic strategies have been undertaken to identify key pathways regulated in pulmonary arterial hypertension that could serve as biomarkers including genomic, transcriptomic, proteomic, and metabolomic approaches. Other biologically relevant components such as circulating cells, microRNAs, exosomes, and cell-free DNA have recently been gaining attention. Because of the size of the datasets generated by these omic approaches and their complexity, artificial intelligence methods are being increasingly applied to decipher their meaning. There is growing interest in imaging the lung with various modalities to understand and visualize processes in the lung that lead to pulmonary vascular remodeling including high resolution computed tomography, Xenon magnetic resonance imaging, and positron emission tomography. Such imaging modalities have the potential to demonstrate disease modification resulting from therapeutic interventions. Because right ventricular function is a major determinant of prognosis, imaging of the right ventricle with echocardiography or cardiac magnetic resonance imaging plays an important role in the evaluation of patients and may also be useful in clinical studies of pulmonary arterial hypertension.

Emerging therapies for right ventricular dysfunction and failure.

Therapeutic options for right ventricular (RV) dysfunction and failure are strongly limited. Right heart failure (RHF) has been mostly addressed in the context of pulmonary arterial hypertension (PAH), where it is not possible to discern pulmonary vascular- and RV-directed effects of therapeutic approaches. In part, opposing pathomechanisms in RV and pulmonary vasculature, i.e., regarding apoptosis, angiogenesis and proliferation, complicate addressing RHF in PAH. Therapy effective for left heart failure is not applicable to RHF, e.g., inhibition of adrenoceptor signaling and of the renin-angiotensin system had no or only limited success. A number of experimental studies employing animal models for PAH or RV dysfunction or failure have identified beneficial effects of novel pharmacological agents, with most promising results obtained with modulators of metabolism and reactive oxygen species or inflammation, respectively. In addition, established PAH agents, in particular phosphodiesterase-5 inhibitors and soluble guanylate cyclase stimulators, may directly address RV integrity. Promising results are furthermore derived with microRNA (miRNA) and long non-coding RNA (lncRNA) blocking or mimetic strategies, which can target microvascular rarefaction, inflammation, metabolism or fibrotic and hypertrophic remodeling in the dysfunctional RV. Likewise, pre-clinical data demonstrate that cell-based therapies using stem or progenitor cells have beneficial effects on the RV, mainly by improving the microvascular system, however clinical success will largely depend on delivery routes. A particular option for PAH is targeted denervation of the pulmonary vasculature, given the sympathetic overdrive in PAH patients. Finally, acute and durable mechanical circulatory support are available for the right heart, which however has been tested mostly in RHF with concomitant left heart disease. Here, we aim to review current pharmacological, RNA- and cell-based therapeutic options and their potential to directly target the RV and to review available data for pulmonary artery denervation and mechanical circulatory support.