Pulmonary Vascular Resistance Predicts Mortality and Graft Failure in Transplantation Patients With Portopulmonary Hypertension

Abstract

Portopulmonary hypertension (POPH) is a pulmonary vascular disease associated with significant morbidity and mortality in those with liver disease, conferring a higher mortality in patients awaiting liver transplantation (LT). Although not a transplant indication, patients with POPH can experience significant clinical improvement following LT, and those maintaining a mean pulmonary artery pressure (MPAP) <35mm Hg and a pulmonary vascular resistance (PVR) <5 Woods units (WU) are granted additional listing points to expedite LT. The effect of POPH on posttransplant outcomes such as mortality and graft failure, however, is not well defined. We performed a retrospective cohort study of the US Organ Procurement and Transplantation Network database of all adult patients who underwent LT between January 1, 2006, and December 1, 2020. Using adjusted accelerated failure time models, we examined the relationship between a diagnosis of POPH and outcomes following LT and the relationship between pre-LT hemodynamics and post-LT survival (alive with a functioning graft) in patients with POPH. Compared with those undergoing transplants without exception points, patients with POPH had comparable post-LT survival rates but were significantly more likely to have graft failure. Both pre-LT MPAP and PVR predicted post-LT survival in POPH, with a pre-LT PVR of ≥1.6 WU, more than doubling the hazard for mortality (death or a nonfunctioning graft; coefficient, 2.01; standard error, 0.85; hazard ratio, 2.21; P = 0.02). POPH may confer a significantly higher risk of post-LT graft failure compared with patients with cirrhosis without POPH, and a pre-LT PVR of ≥1.6 WU may predict post-LT survival. Further investigation into the relationship between pre-LT hemodynamics, right ventricular function, and post-LT outcomes of mortality and graft failure in POPH is needed.

Figure 1:

Flow of Patients Through the Study Abbreviations: TRR – Transplant recipient registration, LT – liver transplantation, PoPH – portopulmonary hypertension, MELD – model for end-stage liver disease

Figure 2:

Kaplan-Meier survival curve comparing survival over 10 years after LT in patients granted PoPH MELD exception points compared to those not granted any exception points Abbreviations: MELD - MELD – model for end-stage liver disease, PoPH – portopulmonary hypertension, LT – liver transplantation

Figure 3:

Kaplan-Meier survival curve comparing graft failure over 10 years after LT in patients granted PoPH MELD exception points compared to those not granted any exception points Abbreviations: MELD - MELD – model for end-stage liver disease, PoPH – portopulmonary hypertension, LT – liver transplantation

Figure 4:

Kaplan-Meier survival curve comparing survival over 10 years after LT in patients granted PoPH MELD exception points stratified by a pre-transplant PVR cut-point of 1.6 WU Abbreviations: MELD - MELD – model for end-stage liver disease, PoPH – portopulmonary hypertension, LT – liver transplantation, PVR – pulmonary vascular resistance, WU – Woods Units