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Abstract Rationale Pulmonary hypertension (PH) is a heterogeneous condition classified into 5 WSPH groups but lacking detailed molecular distinction. The PVDOMICS cohort includes all PH groups alongside healthy and disease comparators, is deeply clinically phenotyped and has RNA sequencing data. Pseudogenes are conserved genome elements that due to sequence-defects cannot be translated into functional proteins. Some pseudogenes never-the-less produce RNA-transcripts which can regulate the expression of other, protein coding genes. Therefore, our study was focused on identifying differentially expressed pseudogene-transcripts within the dataset from the PVDOMICS study and gaining insights into their potential function. Methods Peripheral venous whole blood was collected from PVDOMICS participants [n = 525 PH patients; n = 312 controls without PH who were comparators (n = 256) or healthy (n = 56)]. RNA was isolated, RNA sequencing was performed. After quality control, differential transcript expression between PH and control groups was analyzed using the limma-voom pipeline, rSEA with adjustment for age, sex, race, smoking, WSPH group, latent factors and false discovery rate. We focused on a) transcripts expressed at increased levels (n = 218): the first 200 DEG (differentially-expressed-genes)-transcripts based on log2 difference plus increased DEG within the first 200 most significant p-values; and b) transcripts expressed at decreased levels (n = 292): last 200 DEG based on log2 difference plus decreased DEG within the first 200 most significant p-values. Results Six pseudogene transcripts were among the increased and 35 pseudogene transcripts were among the decreased DEG in the PH group compared to controls. Some of the differentially expressed pseudogenes (DEP) belonged to gene families, like the ribosomal protein family (7 DEP), mitochondria expressed transcripts (3 DEP), zinc finger proteins (2 DEP). Associations of pseudogenes with biological function or disease were extracted via GeneCards(R) and information from GWAS analysis. The DUSP8P5 pseudogene was among the DEP and is known for its association with left heart disease and hypertension; 2 additional DEP have known association with hypertension. Further known associations were with inhibitory or inflammatory immune processes (8 DEP), bone density (6 DEP), metabolism and diabetes (6 DEP), respiratory function or disease (4 DEP), erythrocyte biology (3 DEP), cancer (5 DEP), kidney disease (1 DEP), and demographic parameters like eye or hair color (2 DEP). Ten DEP had no known association with function or disease. Conclusions We identified pseudogene RNA-transcripts associated with PH across WSPH groups. The local vs. systemic effects of these pseudogene transcripts on PH remain to be determined and regulators of pseudogene-transcript expression (e.g. environmental exposures) identified. This abstract is funded by: 1 X01 HL148611 (TopMed), PVDOMICS NHLBI, PVDOMICS Pulmonary Hypertension Association, HT9425-25-1-0533 (GG), 1R21OH012955-01 (GG)

Abstract Introduction Catheter-directed thrombolysis (CDT) has emerged as a safer interventional option for acute pulmonary embolism (APE) compared to systemic thrombolysis, with reduced rates of hemorrhage and mortality. However, comparative outcomes between first-time and recurrent APE patients undergoing CDT remain inadequately documented. This study aims to compare complications, mortality, and readmissions following CDT in recurrent versus first-time PE to provide evidence-based guidance for treatment optimization. Methods We explored the 2016-2022 Nationwide Readmissions Database(NRD) for APE admissions treated with CDT and stratified our sample by history of prior pulmonary embolism. Our cases excluded patients with COVID-19 and those younger than 18 years. We compared differences in their demographics, in-hospital complications during the index admission, and 30-day readmission rates. Adjustments were made to account for the complex design of the NRD via STATA 18.0. Results Of 37,952 patients identified, 9.27% had a history of prior PE. The groups had comparable mean age, sex distribution, and hospital status, with varying comorbidities as shown in Tables 1a-1b. Patients with first-time PE were more likely to experience in-hospital complications including sepsis, transfusion requirement, invasive mechanical ventilation, shock, acute encephalopathy, acute kidney injury, and all-cause mortality during the index hospitalization(Table 2). However, hospital length of stay and charges were similar between groups(Table 1b). Following discharge, 30-day readmission rates were comparable (6.25% vs. 6.41% for first-time versus recurrent PE, respectively; hazard ratio 0.948, 95% CI 0.765-1.17, p = 0.626). Conclusion First-time APE patients who underwent CDT reported higher rates of various in-hospital complications, and all-cause mortality, despite having comparable 30-day readmission rates. There were certain limitations to our study, such as the lack of laboratory data, imaging findings, APE severity scores on admissions, and medication history. Prospective studies with detailed clinical parameters will help validate our findings and elucidate the different causes of death. This abstract is funded by: None

Abstract Rationale Chronic thromboembolic disease (CTED), which is the result of persistent pulmonary vascular obstruction despite 3 months of anticoagulation, can present with significant functional limitations and exercise intolerance despite normal resting hemodynamics. These patients may experience functional impairment due to exercise-induced pulmonary hypertension, impaired stroke volume augmentation with exercise, ventilatory inefficiency, and/or preload insufficiency. Such exercise-induced pathophysiological abnormalities can significantly impair quality of life and contribute to poor long-term outcomes. Although balloon pulmonary angioplasty (BPA) has shown benefit in patients with chronic thromboembolic pulmonary hypertension (CTEPH), its role in CTED patients with normal resting hemodynamics remains uncertain. This systematic review and meta-analysis evaluated the efficacy of BPA in this population. Methods A systematic search of PubMed, Cochrane, Embase, and Scopus was performed from inception through March 1, 2025. A total of 763 studies were screened, of which 42 full-text articles were assessed: six met the inclusion criteria (four retrospective, two prospective), comprising 98 patients. Results Across the included studies, baseline mean values were 20.81 +/- 3.62 mmHg for mean pulmonary arterial pressure (mPAP), 3.49 +/- 1.42 Wood units for pulmonary vascular resistance (PVR), and 405.72 +/- 108.40 m for the 6-minute walk distance (6MWD). Balloon Pulmonary Angioplasty (BPA) was consistently associated with significant improvements in hemodynamic and functional outcomes; BPA reduced mPAP by 3.40 mmHg and PVR by 0.90 WU, while increasing 6MWD by 31.90 m. These changes were also statistically robust across studies, with pooled standardized mean changes (SMC) of -0.88 for mPAP (95% CI, -1.10 to -0.67; P < .05), -0.68 for PVR (95% CI, -0.87 to -0.49; P < .05), and 0.29 for 6MWD (95% CI, 0.13 to 0.45; P < .05). Study-level effect sizes for 6MWD ranged from 0.19 to 0.54 (Figure 1A). Functional improvements were further demonstrated by shifts in NYHA class distribution (Figure 1B). Conclusion BPA was associated with meaningful reductions in mPAP and PVR and significant improvements in functional capacity among patients with CTED. These results indicate that BPA could be an effective treatment for certain patients with CTED, though more research is necessary. This abstract is funded by: None

Abstract Rationale Chronic thromboembolic disease (CTED) is characterized by persistent pulmonary vascular obstruction due to unresolved thromboemboli despite at least three months of anticoagulation. Although resting hemodynamics often remain normal, affected patients frequently develop functional limitation due to exercise-induced pulmonary hypertension, ventilatory inefficiency, limited stroke volume augmentation, or preload insufficiency. Such exercise-induced pathophysiological dysregulation can significantly impair quality of life and contribute to poor long-term outcomes. Pulmonary endarterectomy (PEA) is an established treatment for Chronic Thromboembolic Pulmonary Hypertension (CTEPH), offering significant improvements in hemodynamics and survival. Its role in CTED, however, remains unclear. While CTED has traditionally been managed with anticoagulation and supportive therapy, emerging evidence suggests PEA may provide symptomatic and functional benefit in selected CTED patients. Given the ongoing uncertainty regarding the role of PEA in CTED, we performed a systematic review and meta-analysis to define its safety profile and clinical efficacy in this patient subset. Methods A systematic search of PubMed, Cochrane, Embase, Scopus, Web of Science, ClinicalTrials.gov, and Google Scholar was conducted from database inception to March 1, 2025. Of 2,244 records screened, 34 full-text articles were assessed, and seven met the inclusion criteria. Results Across the included studies, the pooled baseline mean values were 20.48 ± 3.03 mm Hg for mean pulmonary arterial pressure (mPAP), 2.83 ± 1.11 Wood units for pulmonary vascular resistance (PVR), and 397 ± 100.08 m for the 6-minute walk distance (6MWD). Pulmonary Endarterectomy (PEA) was consistently associated with significant improvements in hemodynamic and functional outcomes; PEA reduced mPAP by 3.58 mmHg (pooled Standardized Mean Change (SMC)=-1.03; 95% CI, -1.23 to -0.83; P < .05), PVR by 0.86 Woods units (pooled SMC=-0.86; 95% CI, -1.05 to -0.67; P < .05), while, conversely, increased 6MWD by 37.49 m (pooled SMC, 0.49; 95% CI, 0.32 to 0.67; P < .05). Study-level effect sizes for 6MWD ranged from 0.21 to 1.47 (Figure 1A). This clinical improvement is further reflected in the enhancement of the NYHA functional class, as illustrated in Figure 1B. Conclusion PEA was associated with significant reductions in mPAP and PVR, as well as a considerable improvement in functional capacity in patients with CTED, with robust results across multiple tests for bias, influence, and sensitivity analyses. These findings support PEA as a viable therapeutic option for selected patients with CTED, although further research is warranted. This abstract is funded by: None

Abstract Rationale Pulmonary hypertension (PH) is a progressive, heterogeneous group of disorders leading to right heart failure and death. Despite advances in management, population-level mortality trends among older adults remain poorly characterized. Understanding these long-term trends is essential for designing equitable, population based interventions. Methods We analyzed mortality data for adults aged 65 years and above using the CDC WONDER database from 1999 to 2020. PH related deaths were identified using ICD 10 codes (I27.0, I27.2,I27.8,I27.9). Age adjusted mortality rates (AAMR) per 100,000 population were calculated and stratified by sex, race and comorbid conditions including hypertension, type 2 diabetes mellitus and congestive heart failure. Temporal trends were evaluated using joinpoint analysis to estimate average annual percent change (AAPC) with corresponding p-values. Results From 1999 to 2020, a total of 141,243 PH related deaths occurred among US adults aged 65 years and above, corresponding to an overall AAMR of 9.1 per 100,000 (95% CI, 8.9-9.3). Annual mortality increased from 5.2 in 1999 to 13.4 in 2020, a 2.6-fold rise (AAPC +3.8%; p < 0.001). Females accounted for 63.7% of all PH deaths and had higher mortality than males (10.8 vs 7.2 per 100,000). Black individuals experienced the highest mortality (12.5 per 100,000), exceeding rates among White (8.7) and Hispanic (7.9) counterparts. The proportion of PH deaths associated with cardiometabolic comorbidities rose substantially, with the largest annual increase seen in PH with coexisting HTN (+4.9% per year), followed by CHF (+4.6%) and T2DM (+4.1%). Conclusions Despite therapeutic progress, overall PH related mortality among older U.S. adults rose significantly from 1999 to 2020. Persistent sex and race based disparities highlight inequities in disease burden and access to care. The increasing coexistence of cardiometabolic comorbidities suggests evolving pathophysiology and emphasizes the need for prevention focused, multidisciplinary strategies. Future work should explore modifiable risk factors and healthcare system determinants driving these trends to inform targeted public health and policy interventions. This abstract is funded by: None

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

Abstract Rationale Pulmonary hypertension (PH) is classified into five groups. Diagnosis requires multiple tests delaying treatment. This study compared patient and diagnostic characteristics for pulmonary arterial hypertension (PAH; Group 1 PH), Group 2-5 PH, and non-PH using machine-learning in an Electronic Health Record (EHR) dataset. This is novel as prior studies use claims data which may lack hemodynamic parameters. Methods This study analyzed adult patient records from a HIPPA-complaint EHR dataset from Mayo Clinic (2015-2024). Cohort definitions: PAH: right heart catheterization (RHC) data [mPAP>20 mmHg, PVR>2 WU, PCWP≤15 mmHg]; ≥2 PAH ICD diagnosis codes or positive natural language processing (NLP) sentiments separated by ≥ 30 days; and use of at least one PAH medication within six months after index date. Group 2-5 PH: RHC (mPAP>20mmHg) and ICD codes or positive NLP sentiment separated by ≥ 30 days for corresponding PH subtype. Non-PH: mPAP ≤ 20 mmHg and/or TRV ≤ 2.8 m/s. Index was the earliest NLP or ICD for PAH, earliest RHC for group 2-5 PH and most recent TRV/ mPAP for the non-PH cohort. Clinical variables were analyzed one-year before study index acknowledging data missingness as a limitation of retrospective dataset studies. Results 593 PAH, 817 Group 2-5 PH (67% with group 2 PH), and 11,600 non-PH patients (1:10 propensity-matched) were identified. Age, race, and symptoms were similar across cohorts. PAH had the highest proportion of females (60%) [Group 2-5 PH (50%) and non-PH cohort (53%)]. Clinical characteristic comparison is presented in Table 1. Comorbidities differed across cohorts. RHC: As expected, compared to Group 2-5, the PAH cohort had higher mPAP and PVR and lower PCWP. confirming a distinctly pre-capillary profile. ECHO: Compared to Group 2-5 PH, the PAH cohort had more pronounced right ventricular (RV) pressure overload and dysfunction and more impaired RV longitudinal strain, while TAPSE was similar. At the same time, left heart structure was less affected in PAH compared to Group 2-5. Among laboratory tests, serum creatinine was higher in Group 2-5 and ANA was higher in PAH cohort. Compared to the no-PH cohort, PAH and Group 2-5 cohorts exhibited clinically non-normal RHC and ECHO findings. Conclusion Although symptoms and demographic characteristics were similar among patients with and without PAH, unique RHC, ECHO, laboratory profiles and comorbidities differentiated PAH patients. Screening techniques using these distinct profiles could be considered to facilitate earlier diagnosis and treatment of PAH in clinical settings. This abstract is funded by: Merck & Co., Inc., Rahway, NJ, USA

Abstract Rationale Pulmonary arterial hypertension (PAH) is a rare and progressive disease, where the guideline-recommended diagnostic confirmation is via right heart catheterization (RHC). However, due to non-specific symptomology, patients often experience delays in diagnosis that potentially impact disease outcomes. We sought to develop a machine learning (ML) based approach for early and appropriate detection of PAH. Methods Three cohorts were derived from Mayo Clinic electronic health record (EHR): confirmed PAH (N = 1,169), No PH (N = 11,600) and Other PH (Group 2-5 PH, N = 817), based on 2022 ESC/ERS guidelines. The study index was defined as the earliest diagnosis dates for PH cohorts (PAH & Other PH) or the latest PH negative echocardiogram (ECHO) or RHC for the No-PH cohort. Patients included in the study had at least one symptom (dyspnea, fatigue, syncope, chest pain, or lower extremity swelling) within one year prior to the study index. A two-step sequential ML modelling strategy was applied: Step 1 differentiated PH (PAH + Other PH) from No PH and step 2 differentiated PAH from Other PH. Models were trained using a combination of structured data, unstructured clinical notes to detect symptoms using natural language processing and ECG waveforms captured one year prior to study index. Models were tested both with and without ECHO parameters. SHAP (SHapley Additive explanations) values were used to determine important features contributing to models (without ECG waveforms). Results Models including ECHO parameters performed better compared to those without (Figure 1). The top feature impacting model without ECHO parameters was dyspnea in the preceding three months followed by heart failure and systolic blood pressure for the PH vs no PH; and T wave peak in V1 and ANA level in PAH vs other PH cohort. The top feature impacting model with ECHO was tricuspid regurgitation velocity followed by heart failure and right atrial pressure for the PH vs no PH; and mean blood pressure and left ventricular diameter in the PAH vs other PH cohort. Figure 1: Model performance in the two-step sequential approach PR-AUC=Precision Recall-Area Under Curve Conclusion This study demonstrates that ML models can aid in the identification of PAH in symptomatic patient populations. While ECG can identify patients for further testing, ECHO can further increase the accuracy and the need to refer patients to RHC for confirming diagnosis of PAH. This abstract is funded by: Merck & Co., Inc., Rahway, NJ, USA

Abstract Background Single breath diffusing capacity of the lung for carbon monoxide (DLCO) remains the most widely used test to assess pulmonary gas exchange. GLI DLCO reference equations are based on a larger, more diverse dataset and offer age-specific and internally consistent reference values. However, their impact on interpretation in a real-world population remains uncertain. Research Question Describe the direction and magnitude of DLCO interpretation changes resulting from our multicenter PFT laboratory transition from Miller to GLI reference equations. Study Design and Methods In this multicenter cross-sectional study, we reanalyzed 88,060 DLCO measurements in a large pulmonary function laboratory database performed between 2016 and 2022 using GLI and Miller reference equations, stratified by self-reported race and ethnicity. Baseline patient characteristics and lung function measurements were summarized with continuous characteristics as median (IQR) and categorical variables as n (%). Kruskal-Wallis test was used to evaluate the difference between GLI and Miller DLCO % predicted difference between races, and two-by-two and four-by-four tables were generated to summarize the proportion of concordance and discordance of GLI to Miller severity levels. A repeated measures multivariable logistic regression was used to evaluate discordance between GLI and Miller severity and patient characteristics (age, sex, race, and BMI). Results We included 63,357 individuals with 88,060 PFT visits; 91.6% (58,076) identified as Caucasian, 5.2% (3,262) as Black, 1.4 % (895) as Asian, and 1.8% (1,113) as mixed/other race. Fifty-one percent were female with an median age of 64 years (range: 5- 85). 7.4% (6509) of DLCO results were discordant, with 0.5% (n = 439) abnormal by GLI only, and 6.9% (n = 6070) abnormal by Miller only. Compared to the Miller, GLI interpretations were associated with a greater shift toward normal interpretations. Younger age, lower BMI, female sex, and being of NE Asian, SE Asian, or Other/mixed race compared to Caucasian were associated with higher odds of discordance in DLCO severity/normal classification. Interpretation The use of GLI reference equations substantially alters the interpretation of DLCO results, shifting a meaningful subset of patients from abnormal to normal classification. While GLI reference equations offer more comprehensive, population-based approach, it is crucial to place these interpretations within the context of the patient presentation until further investigations more clearly define the clinical implications of these transitions. This abstract is funded by: none

Abstract Rationale Premature birth necessitates interventions such as supplemental O2 (hyperoxia, typically <60% O2) with or without respiratory support primarily using nasal CPAP. The static stretch of CPAP can induce sustained airway hyperresponsiveness (AHR) and airway thickening (remodeling) even after CPAP is stopped - effects that contribute to a wheezing phenotype and predispose to asthma, major sources of respiratory morbidity in former “preemies.” Effects of CPAP can impact airway smooth muscle (ASM), a key cell type in asthma. We sought to find out if mechanosensitive Piezo (PZ) channels in developing ASM contribute to CPAP-induced AHR and remodeling. In other cell systems, PZ affects the Wnt/β-catenin (β-cat) pathway, but there is currently little information on how stretch influences this pathway and its downstream role in developing ASM. Our overall hypothesis is that in developing airways, PZ channels and downstream Wnt/β-cat pathway are linked in the context of stretch effects, leading to AHR and remodeling. Methods Fetal ASM (fASM) cells were isolated from lungs of 18-20-week fetuses (Mayo IRB exempt). Neonatal mice (comparable to late gestation humans) were also used; lung tissue was harvested following IACUC protocols. Western blot (WB), qRT-PCR, immunofluorescence imaging (IF), extracellular matrix (ECM) deposition assay, proliferation assay, and precision cut lung slice (PCLS) imaging were performed. Stretch conditions used were “non-stretch” (0% static strain imposed on 5% cyclic strain representing normal breathing) or “stretch” (5-10% static strain imposed on 5% cyclic strain, representing superimposed CPAP). Compounds used were Yoda1 (PZ1 agonist), GsMTx4 (PZ inhibitor), DKK1 (Wnt pathway inhibitor), and Wnt3a ligand. Results PZ1 and PZ2 are expressed in fASM and stretch increased expression of both, shown by qRT-PCR and WB. In neonatal mice exposed to CPAP, lumen area of PCLS were decreased compared to control; GsMTx4 alleviated this effect. Stretch increased ECM in fASM, however the effect was blunted by GsMTx4. Stretch increased mRNA for canonical Wnt pathway elements and decreased negative regulatory elements. Stretch increased GSK3β protein phosphorylation and β-cat protein nuclear translocation; effects blunted by DKK1. Wnt3a ligand increased proliferation and ECM in fASM. Stretch increased Wnt3a mRNA and β-cat protein nuclear translocation, with effects blunted by GsMTx4. Stretch alone or in combination with Wnt3a ligand, as well as Yoda1 alone, increased nuclear β-cat, shown qualitatively by IF. Conclusions Our study showed that Wnt/β-cat may be a novel, important, and conceivably targetable pathway (e.g. with PZ modulators) in alleviating potentially long-term, detrimental airway responses to CPAP. This abstract is funded by: NIH R01 HL056470 (Prakash), R01 HL177837 (Pabelick)