Applicability of the 3-Strata ESC/ERS risk model at baseline in pulmonary veno-occlusive disease
Authors: Cruz Utrilla A , Perez-Olivares Delgado C , Luna-Lopez R , Jimenez Lopez-Guarch C , Segura De La Cal T , Bedate P , Lopez-Meseguer M , Gallego Zazo N , Tenorio-Castano J , Escribano-Subias P 
Published: November 2023

Abstract

Introduction
The risk of death or lung transplantation in Pulmonary Arterial Hypertension (PAH) is influenced by many factors. The recently published European Society of Cardiology/ European Respiratory Society (ESC/ERC) Guidelines for the study and management of PAH recommend the use of a multiparametric 3-strata model for risk stratification at diagnosis [1]. Heritable pulmonary veno-occlusive disease (PVOD) is an especially infrequent form of PAH caused by homozygous variants in the gene encoding the Eukaryotic Translation Initiation Factor 2 Alpha Kinase 4 (EIF2AK4). PVOD has a dramatically low long-term survival. There is no evidence confirming the applicability of the risk scores in PVOD. Our aim was to evaluate the usefulness of the 3-strata ESC/ERC score at diagnosis in patients with heritable PVOD.

Methods
We considered patients with the diagnosis of heritable PVOD included in the Spanish registry of PAH (REHAP) between 2011 and 2022. The diagnosis required a homozygous variant in EIF2AK4, and a diagnostic right heart catheterization (RHC). The other group was composed of patients with PAH and pathogenic or likely pathogenic variants in the gene BMPR2. The prognostic evaluation was done when these patients were included in the registry. All participants signed informed consent.

Results
In the 2011-2022 period up to 32 cases of PVOD in 23 unrelated families and 28 cases in 23 families were collected. 10 patients were excluded due to incomplete RHC at diagnosis. The baseline characteristics of the population can be seen in the Table. After a median follow-up of 16.9 months, up to 15 patients with PVOD needed lung transplantation (46.9%), and 6 patients died (18.7%). On the contrary, only 4 patients needed lung transplantation and one died in the BMPR2 group after a median follow-up of 97.1 months. Most of the included PVOD patients had an intermediate risk of mortality after the application of the 3-strata European model (62.5%), and only one case (3.1%) was categorized as high-risk. There was a non-significant tendency for patients with BMPR2 variants to have lower risk levels. The application of the 3-strata model at diagnosis in patients with PVOD demonstrated a good global prognostic capacity (C Index of 0.707). In our PVOD population, those patients at intermediate risk had a hazard ratio of 9.53 (2.15-42.17, p=0.003) when compared with patients at low risk. Similarly, those patients at high risk at diagnosis had a hazard ratio of 9.49 (0.86-104.69, p=0.066) when compared with patients at intermediate risk (Figure).

Conclusions
The application of the ESC/ERC three-strata risk tool in patients with PVOD demonstrates a good global prognostic capacity. Nevertheless, the risk of death or lung transplantation can be higher than predicted in this population, enhancing the need for an early evaluation for lung transplantation.Figure