Krowka, Michael J.

Abstract Rationale Portopulmonary hypertension (POPH) and hepatopulmonary syndrome (HPS) are two distinct pulmonary vascular complications of liver disease. POPH is characterized by pulmonary hypertension and elevated pulmonary vascular resistance while HPS is characterized by intrapulmonary vasodilation and hypoxemia. POPH and HPS reflect opposing pulmonary vascular responses with markedly different therapeutic and transplant implications. Accurate distinction on imaging may aid clinical decision-making and risk stratification. We aimed to quantitatively characterize and compare chest CT imaging features of POPH and HPS compared to controls with isolated portal hypertension (PoH). Methods Three cohorts of HPS, POPH, and PoH were included (n = 5 per cohort). POPH patients with intrapulmonary vasodilation on contrast echocardiography were excluded. Contrast-enhanced chest CTs with slice thickness ≤ 1.5mm obtained closest to the time of diagnosis were selected (mean 2.7 years following diagnosis). CT images were analyzed using a deep learning algorithm developed in-house that segmented and computed volumes of central, interlobar, peripheral, upper peripheral, and lower peripheral pulmonary arteries (PAs); total, upper, and lower pulmonary veins (PVs); and the four cardiac chambers. Resulting volumes were indexed by body-surface area. One-way analysis of variance (ANOVA) was performed with a post-hoc pairwise Mann-Whitney U test for comparison. Results Patients with HPS were 80% male, had a mean age of 48.6±17.4, and mean MELD-Na of 15.4±3.4. The POPH cohort was 20% male, had a mean age of 56.8±11.9, and mean MELD-Na of 13.4±4.0. The PoH cohort was 100% male, had a mean age of 62.8±4.8, and mean MELD-Na of 12.8±8.8. HPS patients had smaller central PA volumes (mean 26.4±1.8 mm2/m2) compared to both PoH (mean 38.6±9.8 mm2/m2, p = 0.03) and POPH patients (44.8±10.8 mm2/m2, p = 0.008). HPS patients, however, had larger lower peripheral PA (mean 30.7±1.9 mm2/m2) and PV (mean 28.3±6.7 mm2/m2) volumes compared to PoH (PAs mean 20.1±4.8 mm2/m2, p = 0.008; PVs mean 18.2±2.8 mm2/m2, p = 0.02) and larger lower peripheral PA volumes compared to POPH patients (PAs mean 22.1±5.1 mm2/m2, p = 0.03). There was no significant difference in volumes between POPH and PoH for all segments. Conclusion Compared to PoH and POPH, HPS is associated with lower central PA volume and higher peripheral PA volume in the lower lungs. Volumes were similar between POPH and PoH; however, this may reflect limited statistical power given the small sample size. Larger studies are needed to further delineate imaging distinctions between POPH, HPS, and PoH. This abstract is funded by: NHLBI

Abstract Rationale Sotatercept is a novel activin signaling inhibitor approved for the treatment of pulmonary arterial hypertension (PAH). Sotatercept has been studied in randomized clinical trials, but little is known regarding the real-world use of sotatercept. We sought to describe the safety, tolerability and efficacy of sotatercept in our clinical practice. Methods We performed a combined prospective and retrospective cohort study of all patients treated with sotatercept at Mayo Clinic Rochester since its approval in March 2024. Patients enrolled in a separate clinical trial of sotatercept were excluded from this analysis as their data will be reported separately. Clinical data was abstracted from the electronic health record. Follow-up data was collected at 6 ± 3 months after initiation of sotatercept. Data is summarized as n (%) and mean ± SD. We used paired t-tests to compare baseline and follow-up characteristics within individuals. Results Fifty-eight PAH patients treated with sotatercept were included. Patients were 48.4 ± 37.6 years old at treatment initiation and were predominantly female with a mean duration of PAH of 6.7 years and a range of PAH etiologies including portopulmonary hypertension, congenital heart disease, and pulmonary veno-occlusive disease (Table 1). Twenty-one (36%) of patients had mixed etiologies of PH. Six months after initiation of sotatercept, patients had a significant improvement in NTproBNP (1922 ± 4464 to 363 ± 596 pg/ml, p = 0.04), 6 minute walk distance (378.8 ±144.6 to 395.7±129.5 meters, p = 0.02) and right ventricular systolic pressure (74.6 ± 20.5 to 60.6 ± 20.3 mm Hg, p < 0.001). No patients permanently discontinued due to abnormal laboratory values. Mean highest hemoglobin achieved over the initial 6 months of treatment was 15.5 ± 2.1 g/dL and mean lowest platelet count was 181 ± 74K. Seven patients discontinued sotatercept at a range of 170-275 days after starting. Four patients discontinued due to possible treatment-related adverse effects: 1 each of gastrointestinal hemorrhage, retinal hemorrhage, hypoxia/intrapulmonary vasodilatation and spontaneous bilateral subdural hematomas. Three patients discontinued due to other reasons: newly diagnosed metastatic cancer leading to transition to hospice and two due to lack of improvement. Conclusions In this real-world registry of sotatercept in PAH, sotatercept was well-tolerated among patients with PAH and associated with improvements in exercise capacity, echocardiographic parameters, and NTproBNP. Overall discontinuation due to possible treatment-related adverse effects was low and reasons for discontinuation included bleeding and hypoxia attributed to intrapulmonary vasodilatation. This abstract is funded by: None

Abstract Rationale Non-selective beta-blockers (BB) are the standard of care for variceal prophylaxis in patients with cirrhosis. It is unclear whether BB negatively affect exercise capacity in patients with portopulmonary hypertension (POPH) or hepatopulmonary syndrome (HPS). We hypothesize that BB use is associated with shorter six-minute walk distance (6MWD) in HPS and POPH than in patients without pulmonary vascular complications of liver disease. Methods The Pulmonary Vascular Complications of Liver Disease 2 (PVCLD2) Study enrolled patients evaluated for liver transplantation or pulmonary hypertension at eight U.S. centers (2013-2017). We conducted a retrospective analysis of 333 patients with HPS, POPH, and portal hypertension without lung complications to evaluate whether disease state modified the association of BB on 6MWD. Multivariable linear regression adjusted for a priori covariates including age, sex, body mass index (BMI), MELD-Na, and WHO functional class. An interaction term between disease category and BB use was included. Results We included 85 patients with HPS, 48 with POPH, and 200 patients with liver disease. Compared to liver disease controls, those with HPS were younger, had higher MELD-Na scores, and more often had worse WHO functional class. POPH patients were similar to controls in age and liver disease severity but had higher WHO functional class. Sex, BMI, and left ventricular ejection fraction did not differ significantly between groups. Higher age, BMI, MELD-Na, and WHO functional class were all significantly associated with lower 6MWD while male sex was associated with higher 6MWD. Adjusting for age, sex, BMI, MELD-Na score, and WHO functional class, there was a significant interaction between BB use and disease category (p = 0.024). Patients with HPS had a 53.4 m longer 6MWD with BB use (95% CI 4.21- 102.5, p = 0.03 for interaction) compared to liver disease controls, whereas patients with POPH had a 72.4 m longer 6MWD (95% CI 7.60- 137.2, p = 0.03 for interaction) compared to liver disease controls. Conclusion The association of BB with 6MWD in advanced liver disease appears to be modified by whether a person has a pulmonary vascular complication including HPS or POPH. The mechanisms for these differences and their clinical implications require further study. This abstract is funded by: NIH T32 Grant

Abstract Introduction Sotatercept was FDA-approved for Group 1 pulmonary arterial hypertension (PAH) in spring 2024, but patients with portopulmonary hypertension (POPH) were not included in major clinical trials that led to its approval. Therefore, safety and efficacy of sotatercept is not well-understood among patients with POPH. We present a case of severe POPH treated with sotatercept. Case Report A 61 year-old female presented to pulmonary hypertension (PH) clinic for follow-up of POPH. History notable for cirrhosis in setting of Hepatis C virus and portosystemic shunts status post embolization. She was on triple PAH therapy with sildenafil, macitentan, and IV epoprostenol. She had functional class 2 dyspnea on exertion, and transthoracic echocardiogram (TTE) demonstrated mild-moderate RV enlargement and mild dysfunction, with estimated right ventricular systolic pressure (RVSP) 76 mmHg. Right heart catheterization (RHC) revealed mean pulmonary arterial pressure (MPAP) 46 mmHg, pulmonary vascular resistance (PVR) 7.9 wood units (WU), cardiac output (CO) 4.9 L/minute, and low biventricular filling pressures. She was started on sotatercept, with goal of improving hemodynamics, RV function, and ultimately qualifying for POPH Model for End-Stage Liver Disease (MELD) exception. She returned for assessment several months later and reported progressive dyspnea with decreasing oxygen saturations. Arterial blood gas (ABG) revealed decreased PaO2 (56 mmHg, compared with 64 mmHg approximately 3 months prior before sotatercept initiation). She was noted to have cutaneous telangiectasias on face, chest, upper extremities, and back (Figure 1). TTE showed decreased RV size and improved function and RVSP (62 mmHg) but large intrapulmonary shunt per agitated saline (“bubble”) study. RHC demonstrated improvement in hemodynamics but remained inadequate to meet POPH MELD exception criteria (MPAP 36 mmHg, PVR 4.6 WU). Sotatercept was discontinued. Follow-up ABG demonstrated increase in PaO2 (63 mmHg), similar to prior baseline, and TTE approximately 6 weeks after stopping sotatercept demonstrated notable decrease in intrapulmonary shunting, now described as small. Telangiectasias improved as well. Discussion The use of sotatercept in patient with POPH and/or liver disease remains an exciting area of investigation, and additional clinical studies are warranted. Potential sequelae such as increased intrapulmonary shunting may particularly affect this patient population, given their unique and complex multiorgan pathology. In current clinical practice, close monitoring is essential when using sotatercept among patients with POPH. This abstract is funded by: n/a

Background Right ventricular (RV) maladaptation to elevated pulmonary afterload is the primary determinant of outcomes in pulmonary artery (PA) hypertension; however, the pathobiological mechanisms underlying RV decompensation remain poorly understood. Methods We performed global untargeted metabolomics on plasma from 55 patients who underwent gold‐standard RV‐PA coupling measurements using multibeat pressure volume loop assessment in a single‐center cohort and from 1027 patients with coupling surrogate measurements in a larger multicenter cohort, the PVDOMICS (Pulmonary Vascular Disease Phenomics) study. Age and sex‐adjusted linear regression was performed to identify associations between metabolites and coupling metrics. Additionally, we performed a metabolic flux analysis using gene expression data from RV tissue in an independent cohort of 32 patients. Partial least squares–discriminant analysis was used to identify metabolites and reactions characteristic of the decompensated RV. Results RV‐PA coupling was negatively associated with tricarboxylic acid (TCA) cycle intermediate levels. Specifically, plasma α‐ketoglutarate and fumarate were significantly associated with all coupling metrics in both cohorts. Metabolic flux analysis indicated that decompensated RVs exhibited aberrant TCA cycle activity, including reduced acetyl coenzyme A entry and increased lactate elimination, suggesting a shift from the TCA cycle toward glycolysis at the RV tissue level. Conclusions We identify an association between circulating TCA cycle intermediate levels and RV‐PA uncoupling in 2 independent cohorts, and dysregulated TCA cycle metabolism in decompensated PA hypertension RVs, suggesting that aberrant TCA cycle metabolism could represent a hallmark of RV maladaptation in PA hypertension. Further study of this pathway is warranted to develop novel biomarkers of RV function or RV‐targeted therapies.

ABSTRACT This review concentrates on the determinants of gas exchange abnormalities in liver‐induced pulmonary vascular disorders, more specifically in the hepatopulmonary syndrome. Increased alveolar‐arterial O 2 difference, with or without different levels of arterial hypoxemia, and reduced diffusing capacity represent the most characteristic gas exchange disturbances in the absence of cardiac and pulmonary comorbidities. Pulmonary gas exchange abnormalities in the hepatopulmonary syndrome are unique encompassing all three pulmonary factors determining arterial PO 2 , that is, ventilation‐perfusion imbalance, increased intrapulmonary shunt and oxygen diffusion limitation that, combined, interplay with two relevant nonpulmonary determinants, that is, increased total ventilation and high cardiac output. Behind the complexity of this lung‐liver association there is an abnormal pulmonary vascular tone that combines inhibition of hypoxic pulmonary vasoconstriction with a reduced (or blunted) hypoxic vascular response. The pathology and pathobiology include the presence of intrapulmonary vascular dilatations with or without pulmonary vascular remodeling, i.e. angiogenesis. Liver transplantation, the only effective therapeutic approach to successfully improve and resolve the vast majority of complications induced by the hepatopulmonary syndrome, along with a large list of frustrating pharmacologic interventions, are also reviewed. Another liver‐induced pulmonary vascular disorder with less gas exchange involvement, such as portopulmonary hypertension, is also considered. © 2018 American Physiological Society. Compr Physiol 8:711‐729, 2018.

Portopulmonary hypertension (POPH), pulmonary arterial hypertension that develops in the setting of portal hypertension, has long been of significant interest to the pulmonary, cardiology, and hepatology communities. Optimal management of POPH has been challenging to define due to a lack of evidence from clinical trials regarding pulmonary arterial hypertension therapies and uncertainty regarding the role of liver transplantation (LT). Initially, the high risk of intraoperative and early post-transplant death in predominantly untreated patients with POPH tempered consideration of LT. More recently, the observation that POPH can improve, and sometimes even resolve, following LT, has led to reconsideration of the role of LT in selected patients. The first International Liver Transplantation Society (ILTS) POPH and hepatopulmonary syndrome practice guideline was a multidisciplinary consensus of expert opinions based on available evidence. Since that publication, hemodynamic definitions, management approaches, and POPH MELD exception criteria have evolved, and there have been new randomized controlled trials in POPH as well as studies regarding long-term outcomes. In order to ensure the guidelines remained current and reflected recent evidence, the original writing committee of the 2016 guidelines, leaders of the ILTS Cardiovascular Special Interest Group, and colleagues active in POPH research were invited to participate in the writing committee. In this document, approved for publication by the ILTS executive council, we provide an update to the prior guidelines with expert recommendations to guide and advance POPH management. Recommendations in these guidelines are based on expert opinion and available evidence and were agreed upon by consensus.

Background. The current model for end-stage liver disease (MELD) exception policies for portopulmonary hypertension (POPH) require serial right heart catheterizations (RHCs) every 3 mo to maintain exception points. RHC is necessary for the initial diagnosis of POPH, but the utility of serial catheterizations has not been studied. In patients with POPH MELD exceptions, we sought to compare noninvasive and invasive hemodynamics and determine the sensitivity of echocardiography for the detection of hemodynamically severe POPH that would preclude liver transplant. Methods. We performed a single-center retrospective cohort study of patients with POPH MELD exceptions who underwent liver transplant from December 2008 to January 2024. Results were validated at an external center. Echocardiograms and RHCs performed within 1 mo were compared. Pearson correlation coefficient and Bland-Altman plots assessed the association between echocardiogram and RHC variables. We examined varied echocardiographic parameters to optimize sensitivity for the detection of hemodynamically severe POPH. Results. Twenty-two individuals underwent 60 follow-up RHCs with paired echocardiograms. Right ventricular systolic pressure (RVSP) and cardiac index estimated with echocardiogram were not strongly correlated with RHC measurements at follow-up (RVSP and RHC pulmonary artery systolic pressure: R = 0.30, P = 0.02; cardiac index: R = 0.17, P = 0.21). However, echocardiograms with RVSP ≥48 mm Hg had 100% sensitivity for detecting hemodynamically severe POPH, with 100% negative predictive value. In external validation of 13 paired echocardiograms and RHCs, our algorithm had 64% specificity and 100% negative predictive value. Conclusions. Although echocardiogram and RHC hemodynamic estimates were not strongly correlated, these results could potentially negate the current requirement for repeat RHC every 3 mo to maintain POPH MELD exception.