Schwalbach, Kevin T.

Abstract Rationale Prior studies demonstrate pulmonary artery (PA) enlargement on computed tomography (CT) in pulmonary hypertension (PH). Some patients exhibit markedly enlarged or “aneurysmal” PA dilation, but its clinical relevance remains unclear. We aimed to characterize clinical characteristics, hemodynamics, and survival probability of patients with aneurysmal PA size. Methods Demographics, clinical characteristics, and CT imaging were obtained for individuals with group 1 or 2 PH and matched controls in the Pulmonary Vascular Disease Phenomics cohort. PA diameter was measured using Osirix software. PA diameter was categorized based on previously reported values as normal (<27 mm [females], <29 mm [males]), enlarged (27-39 mm [females], 29-39 mm [males]), or aneurysmal (≥40 mm). Outcomes included mean PA pressure (mPAP) on right heart catheterization (RHC) and time to death or heart/lung transplant. Associations with mortality and mPAP were evaluated using multivariable Cox and linear regression models, adjusting for age, sex, and BMI. Descriptive statistics are presented as median [IQR]. Results 690 subjects met the inclusion criteria for survival analysis (364 WSPH group 1 or matched comparator, 241 group 2 or comparator, 85 healthy control), with 594 undergoing RHC. PA diameter was normal in 163 participants, enlarged in 414, and aneurysmal in 113. Aneurysmal PA, compared with normal or enlarged PA, was associated with younger age (53 ± 14 vs 55 ± 16 and 59 ± 15 years, respectively; p < 0.001), non-White race (18.9% vs 8% and 17.2%; p = 0.034), pro-BNP (1950 ± 5708 vs 531 ±1651 and 110 ± 2258 pg/mL; p < 0.001), PH duration (6.78 ± 6.86 vs 2.24 ± 4.39 and 3.82 ± 5.47 years; p < 0.001), group 1 disease (77% vs 37% and 61%), and congenital heart disease (CHD)-PAH (10.6% vs 0.0% and 4.8%, p < 0.001). Aneurysmal PA subjects had higher mPAP (46 [36-57] vs 19 [16- 25] and 35 [28-47] mmHg, p < 0.001), pulmonary vascular resistance (PVR) (5.5 [3.6-9.4] vs 1.7 [1.0-2.3] and 4.1 [2.4-7.1] Woods units, p < 0.001), cardiac index (CI; 2.73 [2.34-3.29] vs 2.55 [2.13-2.98] and 2.52 [2.12-3.10] L/min/m2, p < 0.02) and likelihood of death or transplant (p < 0.001; Figure 1). Conclusion “Aneurysmal” PA was more common in younger, non-White subjects with longer WSPH group 1 disease duration, CHD, and higher pro-BNP levels. Aneurysmal PA was associated with elevated mPAP, PVR, and CI, and reduced likelihood of survival. These findings highlight the need to further elucidate the pathophysiology and prognostic implications of aneurysmal PA remodeling in PH. This abstract is funded by: NHLBI and the Pulmonary Hypertension Association

Abstract Background We recently reported a strong association between CT markers of pulmonary artery (PA) dilation and mean PA pressure (mPAP) in subjects with World Symposium on Pulmonary Hypertension (WSPH) group 1 and 2 pulmonary hypertension (PH). The relationship between PA size and mPAP in subjects with WSPH group 3 PH, in which parenchymal changes may influence PA dilation, remains uncertain. We sought to investigate this relationship in subjects with and without PH who have significant parenchymal pulmonary disease or hypoxia. Methods We measured PA diameter and PA:aorta (PA:A) ratio on CT for all subjects with WSPH group 3 PH, matched disease comparators, and healthy controls in the Pulmonary Vascular Disease Phenomics (PVDOMICS) cohort. PH and comparator subjects were categorized by group 3 etiology into obstructive (including chronic obstructive pulmonary disease [COPD] and cystic fibrosis), interstitial (including idiopathic pulmonary fibrosis, unspecified interstitial lung disease, combined pulmonary fibrosis and emphysema, and chronic hypersensitivity pneumonitis), and non-parenchymal (including obesity hypoventilation syndrome, obstructive sleep apnea, and extrinsic restrictive disease) subgroups. Primary outcome was mPAP on right heart catheterization (RHC). Association with mPAP was evaluated using multivariable linear regression adjusted for age, sex, and BMI. Results 339 subjects met inclusion criteria (101 WSPH group 3 PH, 153 disease comparators, 85 healthy controls). 83 subjects had obstructive disease, 125 had interstitial disease, and 46 had non-parenchymal disease. PA diameter and PA:A were associated with mPAP in all subjects and in each subgroup (p < 0.001; see figure 1). The association was notably stronger in the non-parenchymal group (ρ = 0.707 for diameter, 0.750 for PA:A) compared to obstructive (ρ = 0.566 for diameter, 0.529 for PA:A) and interstitial (ρ = 0.432 for diameter, 0.373 for PA:A) groups. Change in PA size between 25th and 75th percentile mPAP was lower in the interstitial group (3.88 mm, ratio 0.12) than in the obstructive (4.88 mm, ratio 0.17) and non-parenchymal (4.80 mm, ratio 0.19) groups (see figure 1). Conclusions PA size on CT is associated with mPAP in subjects with chronic lung disease with and without PH. This association is strongest in subjects without parenchymal lung disease but with features of hypercarbia or hypoxia alone. These data suggest that features of parenchymal lung disease in certain patients may limit expected PA dilation in response to elevated PA pressures. Further study is needed regarding the implications of these findings for early identification of PH in patients with chronic lung disease. This abstract is funded by: The NHLBI and Pulmonary Hypertension Association

Abstract Rationale Pulmonary artery (PA) dilation on computed tomography (CT) has been associated with moderate-to-severe ­pulmonary hypertension (PH) using outdated diagnostic criteria. The association between PA size and mean PA pressure (mPAP) in mild PH and the prognostic implications of PA dilation remain unclear. Objectives To investigate associations between PA size, mPAP, and survival in subjects without significant lung disease aside from PH. Methods PA size on CT was measured for individuals with group 1 or 2 PH and matched controls in the Pulmonary Vascular Disease Phenomics cohort. Outcomes included mPAP on right heart catheterization (RHC) and time to heart and/or lung ­transplantation or death. Measurements and Main Results A total of 691 subjects were included, with 595 undergoing RHC. PA diameter and PA:aorta ratio demonstrated significant association with mPAP (ρ = 0.557 and 0.564, respectively). Size increased incrementally from no PH to mild PH to moderate-severe PH for PA diameter (27.64 [95% CI, 17.64-37.64] mm to 30.65 [95% CI, 18.99-42.31] mm to 36.00 [95% CI, 22.46-49.54] mm) and PA:aorta (0.89 [95% CI, 0.53-1.24] to 0.99 [95% CI, 0.63-1.35] to 1.19 [95% CI, 0.60-1.78]). PA diameter and PA:aorta demonstrated good discrimination of mPAP >20 mm Hg (area under the curve: 0.834 and 0.816, respectively). Transplant-free survival decreased across the continuum of PA diameter and PA:aorta (P <.001). Adjusted hazard ratio of third versus first quartile values was 2.36 (95% CI, 1.58-3.54) for PA diameter and 2.24 (95% CI, 1.52-3.30) for PA:aorta. Conclusions In subjects without significant lung disease outside of PH, PA size on CT was associated with increased mPAP and decreased transplant-free survival across the spectrum of PH severity and demonstrated modest diagnostic discriminatory ability using updated hemodynamic criteria.

Abstract Rationale: Prior studies report association between pulmonary artery (PA) dilation on computed tomography (CT) imaging and pulmonary hypertension (PH). These studies predate expansion of PH hemodynamic diagnostic criteria and do not report patient mortality. As such, little is known about the presence of vascular changes in mild PH or their association with survival. We sought to investigate these relationships in individuals without significant parenchymal lung disease. Methods: We obtained CT images for subjects with group 1 or 2 PH, disease comparators, and healthy controls enrolled in the Pulmonary Vascular Disease Phenomics (PVDOMICS) study. We used Osirix imaging software to measure the main, left, and right PA (MPA, LPA, and RPA) and MPA:aorta (PA:Ao) ratio by diameter and cross-sectional area at locations consistent with prior studies. We evaluated associations with mortality and mean PA pressure (mPAP) using multivariable Cox and linear regression models adjusting for age, sex, and BMI. Descriptive statistics are presented as mean ± SD. Results: We identified 558 subjects (59 controls, 138 comparators, and 361 PH [267 group 1, 94 group 2]). 79 subjects had mPAP < 21 mmHg, 39 had mPAP 21-24 mmHg, and 371 had mPAP ≥ 25 mmHg. Increased MPA, LPA, and RPA diameter and area, PA:Aodia, and PA:Aoarea were associated with decreased survival (all p < 0.001) after multivariable adjustment. First versus third quantiles of all measurements were associated with mortality, with adjusted hazard ratio of 2.99 [95% CI 1.77, 5.05] for MPA diameter (2.84 vs 3.82 cm), 3.74 [2.07, 6.74] for MPA area (7.26 vs 12.74 cm2) and 5.24 [2.58, 10.66] for LPA area (4.55 vs 7.03 cm2). All measures significantly increased alongside PH severity from mPAP < 20 to 21-24 to ≥ 25 mmHg (see figure 1 for MPA diameter). All measures positively correlated with mPAP, including MPA diameter (ρspearman = 0.55) and PA:Aodia (ρ = 0.56). After multivariable adjustment, Q1 to Q3 increments in MPA diameter and PA:Aodia were associated with mPAP increase of 12.5 [10.7, 14.4] and 13.9 [11.9, 15.8] mmHg, respectively. BMI showed no correlation with PA size (ρ = 0.076 for MPA area, -0.051 for PA:Aodia). Conclusions: PA size increases alongside PH severity using updated hemodynamic criteria and is associated with incremental increases in PA pressure and mortality. LPA dilation demonstrates particularly strong association with mortality. PA size does not correlate with BMI. These novel findings enhance our understanding of vascular changes across the PH disease spectrum.