Burger, C D

Abstract Rationale Transthoracic echocardiography (TTE) is a very useful measure of cardiac function in patients with pulmonary hypertension (PH), along with right heart catheterization, which is considered to be the gold standard of measurement. It is non-invasive, quick and a good screening tool to assess the function of a failing right ventricle against elevated pulmonary pressures. Portopulmonary hypertension (POPH) is defined as PH associated with portal hypertension. The Tricuspid Annular Plane Systolic Excursion to Systolic Pulmonary Artery Pressure (TAPSE/SPAP) ratio has been found to be an effective prognosticator in different subtypes of PH. This study focuses on the role of TAPSE/SPAP ratio in prognosis of patients with POPH undergoing liver transplantation. Methods This was a single-center retrospective study of POPH patients undergoing liver transplantation at Mayo Clinic Florida from June 2003 to December 2023. It included patients with POPH with a mean pulmonary pressure >20 mm Hg undergoing liver transplantation. Patients with incomplete TTE data, coexisting renal failure on dialysis and requiring liver retransplant were excluded. This study included 27 patients. The last TTE report before liver transplantation was used for data analysis. The TAPSE/SPAP ratio was investigated as predictor of all-cause mortality following liver transplant using Cox regression and area under ROC curve. (Brackets contain 95% C.I.) Time to death after liver transplantation was considered. Patients were followed till August 1, 2024. (The correlation of this ratio-TAPSE/SPAP with some catheterization measured pulmonary pressures and indices have been included in Table 1.) Results Among 27 patients, 13 were female, 14 male. The most common causes of liver failure in these patients were non alcoholic fatty liver disease (NASH) and alcoholic liver disease. Rarely, some etiologies like sarcoidosis, autoimmune hepatitis, primary sclerosing cholangitis and hepatitis B/C were present. There were 7 deaths among total of 27 patients. The hazard ratio (HR) of TAPSE/SPAP for overall mortality by Cox regression was 0.01 (0.00-0.58), p = 0.03. The area under ROC curve was 0.76 (0.55-0.96), p = 0.01 [Also for TAPSE alone, the area under ROC curve was 0.74 (0.51-0.97), p = 0.05] Conclusion This study infers that TAPSE/SPAP ratio seems to be a good predictor of survival in POPH patients undergoing liver transplant, with a higher ratio associated with decreased all-cause mortality. It suggests that TAPSE alone might also be a good predictor with higher TAPSE associated with decreased mortality. This abstract is funded by: None

Abstract Rationale Pulmonary hypertension (PH) develops in up to 50% of patients with advanced interstitial lung disease (ILD) and is associated with increased morbidity, mortality, and impaired quality of life. Early recognition is essential, as available therapy for ILD-PH has been shown to improve outcomes. Identifying physiologic markers of PH may facilitate earlier referral for right heart catheterization (RHC) and initiation of targeted treatment. Thus, this study aimed to (1) compare functional parameters between ILD patients with and without RHC-confirmed PH, and (2) assess the applicability of previously proposed ILD-PH screening criteria. Methods We retrospectively analyzed ILD transplant candidates with available pre-transplant pulmonary function tests (FVC%, DLCO%), echocardiographic right-ventricular systolic pressure (RVSP), six-minute walk distance (6MWD) with oxygen requirement, and RHC data. PH was defined according to the 2022 ESC/ERS criteria. Functional parameters were compared between patients with and without PH. Among those without a prior PH diagnosis, screening thresholds derived from previously published tools were applied (RVSP ≥ 35 mmHg, DLCO < 40%, FVC/DLCO > 1.6, 6MWD < 350 m, or oxygen use during 6MWD). Results Of 107 ILD patients evaluated, 90 had complete RHC data (48 ILD-PH, 42 ILD without PH). Group comparisons are summarized in Table 1. Patients with PH had lower DLCO% (median 18.5 [11.5-26.7] vs 26.5 [20.0-34.7], p = 0.08), higher FVC/DLCO ratios (2.68 [2.1-3.4] vs 1.7 [1.4-2.6], p = 0.08), and higher RVSP (55 [39.7-63.2] vs 39.5 [29-48] mmHg, p = 0.002). Oxygen requirement during 6MWD was more frequent in ILD-PH (79.2% vs 61.9%, p = 0.08). Among patients with PH, 38 (79.16%) had no formal diagnosis prior to pre-transplant RHC. Of these cases, all (100%) met ≥3 screening criteria, most commonly DLCO < 40% (n = 38, 100%), FVC/DLCO > 1.6 (n = 37, 97.3%), and 6MWD < 350 m (n = 33, 86.8%). Additionally, 32 patients (84.21%) met ≥4 criteria and 8 (21.05%) met all five criteria. Conclusion In ILD transplant candidates, patients with PH had worse functional profiles when compared to those without PH, and nearly 80% of PH cases were previously undiagnosed. Systematic application of validated PH screening tools in ILD populations may facilitate earlier recognition, potentially improving patient outcomes. This abstract is funded by: None

Abstract Rationale Treatment of hematologic malignancies has been revolutionized by Chimeric antigen receptor T -cell (CAR-T) therapy. Pulmonary complications are increasingly being reported, however, there are no standardized timelines for pulmonary function test (PFTs) assessment before or after the infusion. We aimed to evaluate changes in lung function (TLC, RV, FEV1, and FEV1/FVC) pre- and post-CAR-T therapy and examine whether these parameters correlate with the development of specific pulmonary complications. Methods We conducted a retrospective chart review of patients above the age of 18 with any malignancy who received CAR-T therapy between June 12, 2018, and December 26, 2023. Pre-CAR-T PFTs were obtained closest to the infusion date, and post-CAR-T PFTs were recorded at the earliest available time following infusion. Pre- and post-CART pulmonary function tests were compared using non-parametric paired tests. In addition, we examined the relationship between baseline PFTs and the subsequent occurrence of pulmonary complications after CAR-T infusion. The Wilcoxon signed-rank test was applied to assess both the magnitude and direction of change while Sign test was used to evaluate only the direction to confirm the consistency of results. These tests were chosen due to small sample size and non-normal distribution of data. Results Among the 68 patients in our cohort, paired pre- and post- CAR-T measurements of pulmonary function were available for 18 patients. FEV1 declined significantly post-infusion (2.70 ± 0.81 L vs 2.28 ± 0.74 L; Z= -2.55, p = 0.011), the FEV1/FVC ratio remained stable (77.8 ± 8.0 vs 80.9 ± 12.2, p = 0.53). Mean TLC and RV remained stable (TLC 5.70 ± 1.18 L vs 4.66 ± 1.02 L, p = 0.17 and 2.13 ± 0.62 L vs 2.00 ± 0.70 L, p = 0.58). There was no significant correlation between the baseline lung function and the development of pulmonary complications. Conclusion Only the pattern of FEV1 decline following CAR-T therapy infusion demonstrates a significant decline, whereas other PFTs, although reduced, did not show significance. While these findings may suggest a restrictive ventilatory pattern, additional data on lung volumes are required to accurately characterize the underlying type of pulmonary function impairment. Although limited by small sample size and non-uniform timing of PFT assessments, this highlights the need for a routine pre-CAR-T pulmonary function evaluation to inform patient selection and baseline risk stratification. This abstract is funded by: None

Abstract Rationale Lymphangioleiomyomatosis (LAM) is a rare, progressive, cystic lung disease affecting women. Sirolimus has been shown to stabilize lung function in women with LAM, but real-world data on long-term safety and efficacy are limited. Methods The NIH Multicenter Safety and Durability of Sirolimus for LAM (MIDAS, NCT02432560) observational registry was launched in 2015. All adult (≥18 years) women with LAM (treated or untreated) were eligible to enroll at any of the 20 U.S. sites and followed longitudinally with serial assessments of lung function, health-related quality of life, and treatment related adverse event (TRAEs). Baseline cohort characteristics and TRAEs are summarized using descriptive analyses. Marginal structural models (MSMs) with inverse probability of treatment weighting estimated the causal effect of sirolimus on annualized forced expiratory volume in one-second (FEV1) decline, adjusting for age at LAM diagnosis, prior treatment with sirolimus, menopausal status, race, presence of angiomyolipomas, supplemental oxygen use; time-varying covariates included diffusing capacity for carbon monoxide (DLCO) and serum vascular endothelial growth factor-D (VEGF-D) levels. Results Longitudinal data was available in 350 LAM patients, most of whom (246, 70.3%) had sporadic LAM. The median age at the baseline pulmonary function test (PFT) measurement was 46 years (range: 19 - 74) and the median (IQR) number of serial PFTs obtained per patient was 3 (1 - 5). The average follow-up duration per patient was 2.8 years. Over half of the patients (196, 56%) were treated with sirolimus during the MIDAS observation period for a median (IQR) treatment duration of 4.9 (2.4 - 7.5) years. MSM analysis demonstrated that sirolimus treatment was durably effective and reduced FEV₁ decline by 74.36 mL/year (95% CI: 15.87 - 132.85) compared with no treatment (-85.31 mL/year for the untreated group vs. -10.95 mL/year for the treated group, p = 0.01). Sirolimus was generally well tolerated; treatment interruption ≥3 months was observed in 38 (19.4%) of the 196 sirolimus treated patients. Logistic regression analysis showed that higher levels of FEV1 (odds ratio: OR = 3.12 [1.45 - 7.11], p = 0.005), VEGF-D (OR = 1.0007 [1.0004 - 1.001], p < 0.001), and DLCO (OR = 1.023 [1.0053 - 1.0413, p = 0.01]), were associated with treatment interruption. Conclusions In the MIDAS cohort, sirolimus treatment resulted in durable stabilization of lung function with a favorable safety profile over a 5-year period. These real-world data support sirolimus as a chronic suppressive therapy for LAM, demonstrating durable efficacy in slowing lung disease progression and tolerability with long-term use. This abstract is funded by: National Institutes of Health