# Impact of flat chest on waitlist mortality in adult patients with pleuroparenchymal fibroelastosis listed for lung transplantation

## TL;DR

Flat chest in patients with a lung disease called PPFE is linked to higher risk of death while waiting for a lung transplant.

## Contribution

This study identifies flat chest as a potential prognostic factor for waitlist mortality in PPFE patients awaiting lung transplantation.

## Key findings

- Low APDT/TDT (flat chest) was associated with shorter waitlist survival in PPFE patients.
- Patients with low APDT/TDT had worse pulmonary function and higher pCO2 levels.
- Flat chest index (APDT/TDT) is a significant risk factor for waitlist mortality.

## Abstract

Pleuroparenchymal fibroelastosis (PPFE) is a distinct subtype of idiopathic interstitial pneumonia, and progressive cases require lung transplantation (LT). Some patients with PPFE develop chest flattening; however, its impact on waitlist mortality for LT remains unclear.

We retrospectively analyzed adult patients with PPFE listed for LT from donation after brain death (DBD) between January 2014 and July 2024. Chest flatness was quantified as the ratio of the anteroposterior diameter of the thoracic cage to its transverse diameter (APDT/TDT). An APDT/TDT cut-off for waitlist mortality was determined by receiver operating characteristic curve analysis. The primary objective was to investigate the prognostic significance of APDT/TDT on waitlist mortality.

Among 36 listed patients, 19 (52.8%) underwent LT, 14 (38.9%) died while awaiting LT, and 3 (8.3%) remained on the waitlist. Patients were classified into high and low APDT/TDT groups: 11 (30.6%) and 25 (69.4%), respectively. The low APDT/TDT group demonstrated shorter 6-minute walk distance (6MWD; P = 0.002), lower percentage forced vital capacity (P = 0.015), and higher pCO2 (P = 0.035). Waitlist survival was shorter in the low APDT/TDT group than in the high group (P = 0.010). Univariate analyses identified low APDT/TDT (P = 0.033), smoking history (P = 0.012), and 6MWD < 400 m (P = 0.007) as risk factors for waitlist mortality.

The APDT /TDT, an index of a flat chest, may serve as a prognostic factor for waitlist mortality in patients with PPFE awaiting LT.