In HF, PH is associated with global pulmonary vascular remodeling, but the severity of PH correlates most strongly with venous and small IV intimal thickening, similar to the pattern observed in PVOD. These findings expand our understanding of the pathobiology of PH in HF.
Aims
Pulmonary hypertension (PH) and pulmonary vascular disease (PVD) are common and associated with adverse outcomes in left heart disease (LHD). This study sought to characterize the pathophysiology of PVD across the spectrum of PH in LHD.
Methods and results
Patients with PH-LHD [mean pulmonary artery (PA) pressure >20 mmHg and PA wedge pressure (PAWP) ≥15 mmHg] and controls free of PH or LHD underwent invasive haemodynamic exercise testing with simultaneous echocardiography, expired air and blood gas analysis, and lung ultrasound in a prospective study. Patients with PH-LHD were divided into isolated post-capillary PH (IpcPH) and PVD [combined post- and pre-capillary PH (CpcPH)] based upon pulmonary vascular resistance (PVR <3.0 or ≥3.0 WU). As compared with controls (n = 69) and IpcPH-LHD (n = 55), participants with CpcPH-LHD (n = 40) displayed poorer left atrial function and more severe right ventricular (RV) dysfunction at rest. With exercise, patients with CpcPH-LHD displayed similar PAWP to IpcPH-LHD, but more severe RV–PA uncoupling, greater ventricular interaction, and more severe impairments in cardiac output, O2 delivery, and peak O2 consumption. Despite higher PVR, participants with CpcPH developed more severe lung congestion compared with both IpcPH-LHD and controls, which was associated lower arterial O2 tension, reduced alveolar ventilation, decreased pulmonary O2 diffusion, and greater ventilation-perfusion mismatch.
Conclusions
Pulmonary vascular disease in LHD is associated with a distinct pathophysiologic signature marked by greater exercise-induced lung congestion, arterial hypoxaemia, RV–PA uncoupling, ventricular interdependence, and impairment in O2 delivery, impairing aerobic capacity. Further study is required to identify novel treatments targeting the pulmonary vasculature in PH-LHD.
Background
The current Organ Procurement Transplantation Network (OPTN) policy grants Model for End Stage Liver Disease (MELD) exception points to patients with portopulmonary hypertension (POPH), but potentially important factors, such as severity of liver disease and pulmonary hypertension, are not included in the exception score, and may affect survival. The purpose of this study was to identify significant predictors of waitlist mortality in patients with POPH.
Methods
We performed a retrospective cohort study of patients in the OPTN database with hemodynamics consistent with POPH [defined as mean pulmonary arterial pressure (mPAP) >25mmHg and pulmonary vascular resistance (PVR) ≥240 dynes•s•cm−5] who were approved for a POPH MELD exception between 2006 and 2014. Using a Cox proportional hazards model, we identified predictors of waitlist mortality (or removal for clinical deterioration).
Results
One hundred ninety adults were included. Age (HR 1.04, 95% CI 1.00-1.08, P=0.0499), initial native MELD score (HR 1.11, 95% CI 1.05-1.17, P<0.001), and initial PVR (HR 1.12 per 100 dynes•s•cm−5, 95% CI 1.02-1.23, P=0.02) were the only significant univariate predictors of waitlist mortality and remained significant predictors in a multivariate model, which had a c-statistic of 0.71. PVR and mPAP were not significant predictors of posttransplant mortality.
Conclusions
Both the severity of liver disease and POPH (as assessed by MELD and PVR, respectively) were significantly associated with waitlist, but not posttransplant, mortality in patients with approved MELD exceptions for POPH. Both factors should potentially be included in the POPH MELD exception score to more accurately reflect waitlist mortality risk.
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