ABSTRACT
OBJECTIVE: Pulmonary artery compliance (PAC), estimated as stroke volume (SV) divided by pulmonary artery pulse pressure (PP), may be a predictor of survival in pulmonary arterial hypertension (PAH). Resistance-compliance (RC) time, the product of PAC and pulmonary vascular resistance, is reported to be a physiological constant. We investigated if differences in PAC and RC time exist between pulmonary hypertension (PH) subgroups and examined whether PAC is an independent predictor of transplant-free survival in PAH. METHODS: This was a retrospective analysis of adult PAH (n=532) and chronic thromboembolic PH (CTEPH, n=84) patients enrolled in the US Pulmonary Hypertension Association Registry from 2015 to 2019. PAC and RC time were compared between PH subgroups (connective tissue disease-PAH (CTD-PAH), idiopathic/heritable-PAH (i/h-PAH), drug/toxin-PAH (d/t-PAH)). Cox proportional hazards models were constructed for transplant-free survival, adjusting for REVEAL 2.0 risk score. RESULTS: There were no differences in estimated PAC between PAH subgroups, nor between PAH and CTEPH. RC time was shorter in CTEPH compared with PAH (median 0.55 (IQR 0.45-0.64) vs 0.62 (0.52-0.73) s, p<0.0001). RC time was shortest in CTD-PAH when compared with i/h-PAH and d/t-PAH ((0.59±0.18) vs (0.65±0.20) vs (0.73±0.25) s, p=0.0001). PAC was associated with transplant-free survival (HR 0.72, 95% CI 0.55 to 0.94, p=0.02) but was not an independent predictor of outcome after adjustment for REVEAL 2.0 score. CONCLUSION: PAC was similar between PH groups and was not an independent predictor of transplant-free survival in PAH. RC time was different between PH subgroups, challenging RC time constancy. TRIAL REGISTRATION NUMBER: NCT04071327.
Subject(s)
Hypertension, Pulmonary , Pulmonary Arterial Hypertension , Adult , Humans , Familial Primary Pulmonary Hypertension , Pulmonary Artery/surgery , Retrospective StudiesABSTRACT
We investigated the prevalence of spirometric restriction in liver transplantation (LT) candidates and the clinical impacts of restriction. We performed a cross-sectional study within the Pulmonary Vascular Complications of Liver Disease 2 (PVCLD2) study, a multicenter prospective cohort study of patients being evaluated for LT. Patients with obstructive lung disease or missing spirometry or chest imaging were excluded. Patients with and without restriction, defined as a forced vital capacity (FVC) <70% predicted, were compared. Restriction prevalence was 18.4% (63/343). Higher Model for End-Stage Liver Disease-sodium score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.11; P = 0.007), the presence of pleural effusions (OR, 3.59; 95% CI, 1.96-6.58; P < 0.001), and a history of ascites (OR, 2.59; 95% CI, 1.26-5.33; P = 0.01) were associated with the presence of restriction, though one-third with restriction had neither pleural effusions nor ascites. In multivariate analysis, restriction was significantly and independently associated with lower 6-minute walk distances (least squares mean, 342.0 [95% CI, 316.6-367.4] m versus 395.7 [95% CI, 381.2-410.2] m; P < 0.001), dyspnea (OR, 2.69; 95% CI, 1.46-4.95; P = 0.002), and lower physical component summary Short Form 36 scores indicating worse quality of life (least squares mean, 34.1 [95% CI, 31.5-36.7] versus 38.2 [95% CI, 36.6-39.7]; P = 0.004). Lower FVC percent predicted was associated with an increased risk of death (hazard ratio, 1.16; 95% CI, 1.04-1.27 per 10-point decrease in FVC percent predicted; P = 0.01). Restriction and abnormal lung function are common in LT candidates; can be present in the absence of an obvious cause, such as pleural effusions or ascites; and is associated with worse exercise capacity, quality of life, and survival.