Pulmonary hemodynamics and transplant-free survival in sarcoidosis-associated pulmonary hypertension: Results from an international registry.

Pulmonary hypertension (PH) is a risk factor for mortality in patients with sarcoidosis. Severe PH in chronic lung disease has previously been defined as mean pulmonary arterial pressure (mPAP) ≥ 35 mmHg or mPAP 25 ≥ mmHg with cardiac index (CI) ≤ 2 L/min/m2. However, there is no clear definition denoting severity of sarcoidosis-associated PH (SAPH). We aimed to determine pulmonary hemodynamic cut-off values where transplant-free survival was worse among patients with SAPH. This was a retrospective cohort analysis of the Registry of SAPH database focusing on pulmonary hemodynamic predictors of transplant-free survival among patients with precapillary SAPH. Cox regression was performed to determine which pulmonary hemodynamic values predicted death or lung transplantation. Kaplan-Meier survival analysis was performed on statistically significant predictors to determine pulmonary hemodynamic cut-off values where transplant-free survival was decreased. Decreased transplant-free survival occurred among SAPH patients with mPAP ≥ 40 mmHg and SAPH patients with pulmonary vascular resistance (PVR) ≥ 5 Woods units (WU). Transplant-free survival was not decreased in patients who fulfilled prior criteria of severe PH in chronic lung disease. We identified new cut-offs with decreased transplant-free survival in the SAPH population. Neither cut-off of mPAP ≥ 40 mmHg nor PVR ≥ 5 WU has previously been shown to be associated with decreased transplant-free survival in SAPH. These values could suggest a new definition of severe SAPH. Our PVR findings are in line with the most recent European Society of Cardiology/European Respiratory Society guideline definition of severe PH in chronic lung disease.

Two Staged Single Lung Transplants in the Current Era: A United Network for Organ Sharing Study.

BACKGROUND: We hypothesized that outcomes after 2 staged, contralateral single lung transplantation procedures (SSLTs) may be equivalent to those of double lung transplantation (DLT) by capitalizing on the known long-term survival advantages of DLT. METHODS: Using the United Network for Organ Sharing data set (1987-2018), the largest national data set available, the outcomes of 278 SSLTs were retrospectively analyzed and compared with the outcomes of 21,121 standard DLTs. RESULTS: During SSLT, the median interval between the 2 transplants was 960 days, and the indication for the second transplant was most often chronic lung allograft dysfunction (n = 148; 53.2%) or the same disease that necessitated the first transplant (n = 81; 29.1%). The patients who underwent SSLT were significantly older and had a higher baseline creatinine level than the patients who underwent DLT. Most posttransplantation short-term outcomes were equivalent between the second stage of SSLT and DLT, but renal insufficiency requiring hemodialysis was notably higher after SSLT. There were no differences in long-term survival. In multivariate analysis, baseline creatinine, O2 support at rest, ventilator support at the time of the second transplantation, and posttransplantation renal insufficiency requiring dialysis were independent predictors of 1-year mortality after SSLT. CONCLUSIONS: Over a study period of 30 years, long-term survival after SSLT was comparable with survival after DLT. With further analysis of individual risk profiles, including the contributions of preoperative renal function and functional status, SSLT can be a valuable option for patients who would have undergone single lung transplantation to reap the long-term benefits of a second transplant.

Lung Transplantation for COVID-19 Pulmonary Sequelae.

BACKGROUND: The role of lung transplantation for coronavirus disease 2019 (COVID-19)-related lung failure is evolving as the pandemic persists. METHODS: From January 2021 to April 2022, 20 patients (median age 62 y; range 31-77) underwent lung transplantation for COVID-related lung failure at our institution. We reviewed their clinical and intraoperative characteristics and early outcomes including postoperative complications. RESULTS: Eleven patients (55%) had chronic lung disease when they contracted COVID-19. All 20 patients required hospitalization for antivirus treatment. Median lung allocation score was 74.7 (33.1-94.0). Thirteen patients (65%) underwent single-lung transplants, and 7 patients (35%) underwent double-lung transplants. Concomitant coronary artery bypass graft surgery was performed in 2 (10%) patients because of severe coronary artery disease. Postoperatively, venovenous extracorporeal membrane oxygenation was needed in 3 patients (15%) because of severe primary graft dysfunction; all were eventually weaned. Ten patients (50%) experienced deep venous thrombosis, and 1 eventually developed a major pulmonary embolus. The median intensive care unit stay and hospital stays were 6.5 d (3-44) and 18 d (7-77), respectively. During a median follow-up of 201 d (47-418), we experienced 1 late mortality due to COVID-19-related myocarditis. Among the 13 patients with single-lung transplant, 5 demonstrated improvement in their native lungs. CONCLUSIONS: Lung transplantation yielded favorable early outcomes in a heterogeneous patient cohort that included older patients, obese patients, and patients with coronary artery disease or preexisting chronic lung disease. Our data also shed light on the transforming role of lung transplantation for the pulmonary sequelae of a complex multisystem COVID-19 disorder.

Predictors of lung transplant waitlist mortality for sarcoidosis.

RATIONALE: Unlike in other chronic lung diseases, criteria for lung transplant referral in sarcoidosis is not well-established. Waitlist mortality may offer clues in identifying clinical factors that warrant early referral. We aim to identify predictors for transplant waitlist mortality to improve referral criteria for patients with sarcoidosis. METHODS: We conducted a retrospective analysis of 1034 sarcoidosis patients listed for lung transplantation from May 2005 to May 2019 in the Scientific Registry of Transplant Recipients (SRTR) database. All patients were listed after the establishment of the Lung Allocation Score (LAS). We compared patients who died on the transplant waitlist to those who survived to transplantation. Potential predictors of waitlist mortality were assessed utilizing univariate and multivariate analysis performed via logistic regression modeling. RESULTS: Of 1034 candidates listed after LAS implementation, 704 were transplanted and 110 died on the waitlist. Significant predictors of waitlist mortality on multivariate analysis include female gender (OR 2.445; 95% CI 1.513-3.951; p = 0.0003) and severe pulmonary hypertension (OR 1.619; 95% CI 1.067-2.457; p = 0.0236). Taller minimum donor height (OR 0.606; 95% CI 0.379-0.969; p = 0.0365) and blood type B (OR 0.524; 95% CI 0.281-0.975 p = 0.0415) were associated with decreased likelihood of death on the waitlist. CONCLUSION: Among patients with sarcoidosis on the lung transplant waitlist, taller minimum donor height and blood type B were found to be protective factors against death on the waitlist. Female gender and severe pulmonary hypertension have a higher likelihood of death and earlier referral for transplantation in patients with these characteristics should be considered.

Single Lung Transplant Remains a Viable Option for Patients With Severe Secondary Pulmonary Hypertension.

BACKGROUND: Although double lung transplant is recommended in patients with severe secondary pulmonary hypertension (SPH), our institutional experiences suggest a role for single lung transplant in these patients. Here, we review our experience prioritizing single lung transplant in patients with SPH to minimize their surgical burden. METHODS: We conducted a retrospective review of our lung transplant database to identify patients with SPH who underwent single lung transplant. Patients were stratified as either mild SPH (mean pulmonary artery pressure 25-40 mm Hg) or severe SPH (mean pulmonary artery pressure >40 mm Hg). Singe lung recipients without PH transplanted over the same time were also examined. RESULTS: Between January 2017 and December 2019, 318 patients underwent single lung transplantation; 217 had mild SPH (68%), and 59 had severe SPH (18.5%). Forty-two patients without PH underwent single lung transplant. When the groups were compared, significantly higher pulmonary vascular resistance was noted in the severe SPH group, and obesity was noted in both the mild and severe SPH groups. Although the severe SPH group required more intraoperative cardiopulmonary support (37.3% versus 10.3% versus 4.7%, P < 0.05), there were no significant differences in most major postoperative parameters, including the duration of postoperative mechanical ventilation or the incidence of severe primary graft dysfunction. Survival 1 y posttransplant was not significantly different among the groups (93.2% versus 89.4% versus 92.9%, P = 0.58). CONCLUSIONS: Our experience supports the option of single lung transplantation with appropriate intraoperative mechanical circulatory support in patients with SPH. This strategy is worth pursuing, especially with ongoing donor lung shortages.

The six-minute walk test in sarcoidosis associated pulmonary hypertension: Results from an international registry.

INTRODUCTION: Sarcoidosis associated pulmonary hypertension (SAPH) is a leading contributor to sarcoidosis-related mortality. The 6-min walk test (6MWT) is widely used in assessment of cardiorespiratory conditions. A reduced 6-min walk distance (6MWD) has been associated with increased mortality in SAPH. We examined patients from the Registry of Sarcoidosis Associated Pulmonary Hypertension (ReSAPH) who had performed 6MWT at enrollment to identify variables that affect 6MWD, and the prognostic value of 6MWT variables regarding death or lung transplantation. MATERIAL AND METHODS: ReSAPH patients with available 6MWT were included. Variables analyzed using pre-defined cutoffs included 6MWD, initial and end of test Borg dyspnea score, oxygen saturation, and heart rate at beginning, end, and after 1-min recovery, absolute change in oxygen saturation, modified distance-saturation product (mDSP), and the heart rate recovery at 1-min (HRR). FINDINGS: 174 patients met inclusion criteria; 48 patients died and 8 underwent lung transplantation. Patients with 6MWD<300 m had a higher chance of dying or undergoing transplantation compared to those with 6MWD>300 m (p = 0.012). No associations with outcome were observed with mDSP cutoff 200 m%, desaturation≥5% and oxygen saturation<88% at end of 6MWT, or multiple HRR cutoffs (13,14,16). 6MWD correlated with initial Borg score, (p = 0.001), DLCO% (p = 0.0001) and sPAP (p = 0.031) on multivariate analysis. These variables were significant for both pre- and post-capillary PH subgroups. 6MWD also correlated with fatigue assessment scale (FAS) (p = 0.015). CONCLUSION: Of the parameters evaluated, 6MWD had the greatest prognostic value in SAPH which correlated with other physiologic and hemodynamic variables. 6MWT captures the multidimensional effects of sarcoidosis.

Effect of antifibrotic therapy in patients with idiopathic pulmonary fibrosis undergoing lung transplant in the peri and post-operative period.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a rapidly progressive interstitial lung disease with high mortality. Lung transplant remains a cornerstone of treatment despite the advent of antifibrotic therapy. In light of the increasing number of patients on antifibrotic therapy prior to lung transplantation it is paramount to demonstrate these medications do not augment postoperative complications following transplant. RESEARCH QUESTION: Does antifibrotic therapy increase perioperative complications and mortality in lung transplant recipients? STUDY DESIGN AND METHODS: We conducted a retrospective chart review of all patients actively listed for lung transplant at Temple University Hospital from June 2014 to April 2017 with a listing diagnosis of IPF. Subjects who received treatment with antifibrotic therapy (either pirfenidone or nintedanib) up until the time of lung transplantation were compared to subjects not on therapy. Data was collected regarding baseline demographics, pulmonary function tests, IPF exacerbations, perioperative bleeding and cardiac events, and outcomes in the postoperative period. RESULTS: A total of 94 subjects were included in the study: 42 subjects on antifibrotic therapy (28 pirfenidone, 14 nintedanib) and 52 subjects not on therapy in the pre-transplant period. Baseline characteristics were similar between study groups. Subjects treated with antifibrotic therapy pre-transplant were noted to have less FVC decline, fewer hospitalizations, and greater weight loss while on the transplant waiting list. No difference in post-transplant airway anastomosis complications, bleeding or mortality was observed between study groups. INTERPRETATION: Subjects with IPF on antifibrotic therapy prior to lung transplantation had better preservation of lung function in the pre-transplant period, and similar outcomes in the postoperative period compared to those not on antifibrotic therapy before lung transplant.

Venous thromboembolism in lung transplant recipients real world experience from a high volume center.

BACKGROUND: Venous thromboembolism (VTE) post lung transplantation is common and has been associated with worse post transplant survival. We report a comprehensive single center review of VTE incidence in the first post transplant year, investigate modifiable risk factors and assess impact on short term outcomes. METHODS: Retrospective review of all lung transplant recipients between August 2016 to 2018 at Temple University Hospital. Patients were followed for 1 year post transplant. All patients were screened for deep venous thrombosis (DVT) within the first 2 weeks with a venous duplex study. Pre transplant, intra operative, post operative variables, and peri-operative practice patterns were compared between VTE positive and VTE negative groups. Logistic regression modeling was used to identify risk factors for early VTE (VTE within 30 days after transplant). RESULTS: A total of 235 patients were included in the study, 58 patients (24.7%) developed a VTE in the first post transplant year. Median time to diagnosis was 17 days. Of the patients with VTE, 76% had an isolated DVT, 13.5 % had an isolated pulmonary embolism (PE), and 10.3% had concomitant DVT and PE. In a multivariate logistic regression model, cardiopulmonary bypass (CPB) (OR 1.93 p = 0.015) and interruption of VTE prophylaxis (OR 4.42 p < 0.0001) were predictive of early VTE. CONCLUSION: VTE post lung transplant is common despite the use of prophylactic anticoagulation. CPB use and interruption of DVT prophylaxis are risk factors for early post transplant VTE. Measures to ensure consistent and uninterrupted prophylaxis may help decrease VTE incidence after lung transplantation.

Guiding therapeutic plasma exchange for antibody-mediated rejection treatment in lung transplant recipients - a retrospective study.

Antibody-Mediated Rejection (AMR) due to donor-specific antibodies (DSA) is associated with poor outcomes after lung transplantation. Currently, there are no guidelines regarding the selection of treatment protocols. We studied how DSA characteristics including titers, C1q, and mean fluorescence intensity (MFI) values in undiluted and diluted sera may predict a response to therapeutic plasma exchange (TPE) and inform patient prognosis after treatment. Among 357 patients consecutively transplanted without detectable pre-existing DSAs between 01/01/16 and 12/31/18, 10 patients were treated with a standardized protocol of five TPE sessions with IVIG. Based on DSA characteristics after treatment, all patients were divided into three groups as responders, partial responders, and nonresponders. Kaplan-Meier Survival analyses showed a statistically significant difference in patient survival between those groups (P = 0.0104). Statistical analyses showed that MFI in pre-TPE 1:16 diluted sera was predictive of a response to standardized protocol (R2  = 0.9182) and patient survival (P = 0.0098). Patients predicted to be nonresponders who underwent treatment with a more aggressive protocol of eight TPE sessions with IVIG and bortezomib showed improvements in treatment response (P = 0.0074) and patient survival (P = 0.0253). Dilutions may guide clinicians as to which patients would be expected to respond to a standards protocol or require more aggressive treatment.

Clinical predictors and explant lung pathology of acute exacerbation of idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is characterised by constant threat of acute exacerbation of IPF (AE-IPF). It would be significant to identify risk factors of AE-IPF. We sought to determine the prognostic value of lung transplantation candidacy testing for AE-IPF and describe explant pathology of recipients with and without AE-IPF before lung transplantation. METHODS: Retrospective cohort study of 89 IPF patients listed for lung transplantation. Data included pulmonary function testing, echocardiography, right heart catheterisation, imaging, oesophageal pH/manometry and blood tests. Explanted tissue was evaluated by pulmonary pathologists and correlated to computed tomography (CT) findings. RESULTS: Out of 89 patients with IPF, 52 were transplanted during stable IPF and 37 had AE-IPF before transplantation (n=28) or death (n=9). There were no substantial differences in candidacy testing with and without AE-IPF. AE-IPF had higher rate of decline of forced vital capacity (FVC) (21±22% versus 4.8±14%, p=0.00019). FVC decline of >15% had a hazard ratio of 7.2 for developing AE-IPF compared to FVC decline of <5% (p=0.004). AE-IPF had more secondary diverse histopathology (82% versus 29%, p<0.0001) beyond diffuse alveolar damage. There was no correlation between ground-glass opacities (GGO) on chest CT at any point to development of AE-IPF (p=0.077), but GGO during AE-IPF predicted secondary pathological process beyond diffuse alveolar damage. CONCLUSIONS: Lung transplantation candidacy testing including reflux studies did not predict AE-IPF besides FVC absolute decline. CT did not predict clinical or pathological AE-IPF. Secondary diverse lung pathology beyond diffuse alveolar damage was present in most AE-IPF, but not in stable IPF.

Current precautions and future directions in lung transplantation during the COVID-19 pandemic - a single center cohort study.

The unprecedented public health emergency caused by the acute viral respiratory coronavirus disease (COVID-19) has drastically changed current practices in solid organ transplantation, markedly so for transplantation of the lungs, the major target of the virus. Although national and state authorities do not recommend postponing transplant procedures, most specialists are reluctant to proceed due to substantial uncertainty and increased risks in the midst of the pandemic. There is an urgent need for evidence-based directions to move forward. Here, we offer our insights as specialists at a high-volume center located in a geographical area with high infection rates.

Pulmonary vasculopathy in explanted lungs from patients with interstitial lung disease undergoing lung transplantation.

BACKGROUND: Pulmonary hypertension (PH) causes increased morbidity and mortality in patients with interstitial lung diseases (ILD). Classification schemes, while well-characterised for the vasculopathy of idiopathic PH, have been applied, unchallenged, to ILD-related PH. We evaluated pulmonary arterial histopathology in explanted human lung tissue from patients who were transplanted for advanced fibrotic ILD. METHODS: Lung explants from 38 adult patients who underwent lung transplantation were included. Patients were divided into three groups: none, mild/moderate and severe PH by mean pulmonary artery pressure (mPAP) measured at pre lung transplantation right heart catheterisation (RHC). Grading of pulmonary vasculopathy according to Heath and Edwards scheme, and prelung transplantation evaluation data were compared between the groups. RESULTS: 38 patients with fibrotic ILDs were included, the majority (21) with idiopathic pulmonary fibrosis. Of the 38 patients, 18 had severe PH, 13 had mild/moderate PH and 7 had no PH by RHC. 16 of 38 patients had severe pulmonary arterial vasculopathy including vascular occlusion with intimal fibrosis and/or plexiform lesions. There were no correlations between mPAP and lung diffusion with the severity of pulmonary arterial pathological grade (Spearman's rho=0.14, p=0.34, rho=0.11, p=0.49, respectively). CONCLUSIONS: Patients with end stage ILD had severe pulmonary arterial vasculopathy in their explanted lungs irrespective of the presence and/or severity of PH as measured by RHC. These findings suggest that advanced pulmonary arterial vasculopathy is common in patients with advanced fibrotic ILD and may develop prior to the clinical detection of PH by RHC.

COVID-19 in lung transplant recipients.

Solid organ transplant recipients are considered at high risk for COVID-19 infection due to chronic immune suppression; little data currently exists on the manifestations and outcomes of COVID-19 infection in lung transplant recipients. Here we report 8 cases of COVID-19 identified in patients with a history of lung transplant. We describe the clinical course of disease as well as preexisting characteristics of these patients.

Physiological predictors of survival in patients with sarcoidosis-associated pulmonary hypertension: results from an international registry.

INTRODUCTION: Sarcoidosis-associated pulmonary hypertension (SAPH) is associated with reduced survival in single-centre studies. The international Registry for SAPH (ReSAPH) with long-term follow-up was established to enrich our knowledge of this complication of sarcoidosis. This analysis aims to elucidate factors associated with reduced transplant-free survival in SAPH patients. METHODS: ReSAPH contains prospectively collected outcomes of SAPH patients since the time of registry enrolment. Information analysed includes right heart catheterisation data, pulmonary function testing, chest radiography, Scadding stage and 6-min walk distance (6MWD), among others. Cox regression models were used to identify independent predictors of transplant-free survival. RESULTS: Data from 215 patients followed for a mean±sd 2.5±1.9 years were available for analysis. In the 159 precapillary patients, the Kaplan-Meier-adjusted 1-, 3- and 5-year transplant-free survival was 89.2%, 71.7% and 62.0%, respectively. Kaplan-Meier-adjusted 1-, 3- and 5-year transplant-free survival in the incident group was 83.5%, 70.3% and 58.3%, respectively, and in the prevalent group was 94.7%, 72.2% and 66.3%, respectively. Patients with reduced diffusing capacity of the lung for carbon monoxide (D LCO) (<35% predicted) and 6MWD <300 m in the precapillary cohort had significantly worse transplant-free survival. Reduced 6MWD and preserved forced expiratory volume (FEV1)/forced vital capacity (FVC) ratio were identified as independent risk factors for reduced transplant-free survival in the precapillary cohort. CONCLUSION: Reduced D LCO (<35% pred) and 6MWD (<300 m) at the time of registry enrolment were associated with reduced transplant-free survival in the overall precapillary cohort. Preserved FEV1/FVC ratio was identified as an independent risk factor for worsened outcomes.

Mortality for sarcoidosis patients on the transplant wait list in the Lung Allocation Score era: Experience from a high volume center.

RATIONALE: Sarcoidosis progresses to end stage fibrotic lung disease in 10% of patients and may necessitate lung transplantation. Organ allocation is currently determined by the Lung Allocation Score (LAS), but its performance in a sarcoidosis population has not been evaluated. OBJECTIVES: To determine sarcoidosis-specific wait list mortality and identify predictive factors of death on the transplantation wait list. METHODS: This was a single-center retrospective study of all sarcoidosis patients listed for lung transplant from March 2012 to February 2019. We compared patients who were transplanted to those who died awaiting organs. We collected baseline listing characteristics, physiologic testing, and outcomes data. Statistical analysis was performed by 2-tailed Student's t-test, Mann-Whitney U test, and Chi-Square analysis (where appropriate). Receiver-operating characteristic curves were constructed for variables reaching statistical significance. RESULTS: Twenty eight sarcoidosis patients were included in analysis. Mortality among wait listed patients was 18%, which exceeded the mortality of COPD and IPF. LAS scores did not differ at initial listing (41 vs. 46, p = 0.35) or at transplant/death (41 vs. 41, p = 0.91); wait list times also did not statistically differ (307 days vs. 177 days, p = 0.19). We identified bilirubin (AUC = 0.92), DLCO (AUC = 0.84), FEV1/FVC at transplant/death (AUC = 0.85), and composite physiologic index (AUC = 0.86) as predictors of death on the transplant list. Pulmonary hypertension was not associated with death. CONCLUSION: Unexpected sudden death was common in our cohort and was associated with markers of advanced fibrotic disease, not pulmonary hypertension.

Effect of Acute Exacerbation of Idiopathic Pulmonary Fibrosis on Lung Transplantation Outcome.

BACKGROUND: Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) has an expected median survival of 3 months. Lung transplantation is a potentially lifesaving therapy for AE-IPF. However, the current knowledge of transplantation outcomes during AE-IPF is limited to a few small retrospective studies, reporting only 1-year post-transplantation survival. METHODS: Study population included patients with IPF consecutively listed for lung transplantation at a single institution between the years 2012 and 2016. We collected lung allocation score (LAS), hospitalization, and survival data. The primary outcome was survival among patients transplanted during stable IPF vs during AE-IPF. RESULTS: Of 89 patients with IPF listed for lung transplantation, 52 were transplanted during stable IPF and 37 were hospitalized due to AE-IPF. Of these 37 patients, nine died before transplantation, and 28 were transplanted during AE-IPF. Fifty percent of patients transplanted during AE-IPF died in a mean follow-up of 1.6 ± 1.2 years compared with 12% of patients transplanted during stable IPF who died in a mean follow-up of 2.6 ± 1.2 years. The Kaplan-Meier survival curves post-transplantation after 1 and 3 years for patients who were transplanted during stable IPF were 94% and 90% vs 71% and 60% in patients who were transplanted during AE-IPF (P = .0001). LAS above 80 conferred a 3-year hazard ratio for mortality of 5.7 vs LAS lower than 80 (95% CI, 2.33-14.0; P < .0005). CONCLUSIONS: Patients with IPF transplanted during AE-IPF had significantly worse short-term and long-term survival compared with patients transplanted during stable IPF. Patients with AE-IPF and very high LAS may not experience the survival advantage expected from lung transplantation.

Clinical features of sarcoidosis associated pulmonary hypertension: Results of a multi-national registry.

BACKGROUND: Pulmonary hypertension (PH) is a significant cause of morbidity and mortality in sarcoidosis. We established a multi-national registry of sarcoidosis associated PH (SAPH) patients. METHODS: Sarcoidosis patients with PH confirmed by right heart catheterization (RHC) were studied. Patients with pulmonary artery wedge pressure (PAWP) of 15 mmHg or less and a mean pulmonary artery pressure (mPAP) ≥ 25 Hg were subsequently analyzed. Data collected included hemodynamics, forced vital capacity (FVC), diffusion capacity of carbon monoxide (DLCO), chest x-ray, and 6-min walk distance (6MWD). RESULTS: A total of 176 patients were analyzed. This included 84 (48%) cases identified within a year of entry into the registry and 94 (53%) with moderate to severe PH. There was a significant correlation between DLCO percent predicted (% pred) andmPAP (Rho = -0.228, p = 0.0068) and pulmonary vascular resistance (PVR) (Rho = -0.362, p < 0.0001). PVR was significantly higher in stage 4 disease than in stage 0 or 1 disease (p < 0.05 for both comparisons). About two-thirds of the SAPH patients came from the United States (US). There was a significant difference in the rate of treatment between US (67.5%) versus non-US (86%) (Chi Square 11.26, p = 0.0008) sites. CONCLUSIONS: The clinical features of SAPH were similar across multiple centers in the US, Europe, and the Middle East. The severity of SAPH was related to reduced DLCO. There were treatment differences between the US and non-US centers.