Incremental prognostic value of arterial elastance in mild-to-moderate idiopathic pulmonary fibrosis

Previous reports suggested that poor pulmonary function was associated with increased arterial elastance (Ea) in patients 
with chronic obstructive pulmonary disease and systemic sclerosis. The mechanisms connecting pulmonary function and Ea 
have not yet been accurately studied in patients with idiopathic pulmonary fibrosis (IPF). The present study was designed to 
assess Ea in IPF patients without chronic severe pulmonary hypertension and to determine its prognostic role over a medium-
term follow-up. This retrospective study included 60 consecutive patients with mild-to-moderate IPF (73.8 ± 6.6 years, 75% 
males) and 60 controls matched by age, sex and cardiovascular risk factors. All patients underwent physical examination, 
spirometry, blood tests, modified Haller index (MHI, chest transverse diameter over the distance between sternum and spine) 
assessment, conventional transthoracic echocardiography implemented with speckle tracking analysis of left atrial positive 
global strain (LA-GSA+ ) and finally carotid Doppler ultrasonography, at basal evaluation. The effective arterial elastance 
index (EaI) was calculated as the ratio of end-systolic pressure to stroke volume index. During follow-up period, we evalu-
ated the composite endpoint of (1) pulmonary or cardiovascular hospitalizations; (2) all-cause mortality. At baseline, EaI 
was significantly higher in IPF patients than controls (4.1 ± 1.3 vs 3.5 ± 1.0 mmHg/ml/m2, p = 0.01). EaI was strongly cor-
related to the following variables: C-reactive protein (CRP) (r = 0.86), forced vital capacity (FVC) (r =  − 0.91), E/e′ ratio 
(r = 0.91), LA-GSA+  (r =  − 0.92), common carotid artery-cross sectional area (CCA-CSA) (r = 0.89) and MHI (r = 0.86), 
in IPF patients. Mean follow-up time was 2.4 ± 1.3 years. During follow-up, 12 patients died and 17 were hospitalized due 
to major adverse clinical events. At univariate Cox analysis, CRP (HR 1.51, 95% CI 1.25–1.82), FVC (HR 0.88, 95% CI 
0.85–0.91), LA-GSA+  (HR 0.85, 95% CI 0.77–0.94), CCA-CSA (HR 1.12, 95% CI 1.03–1.22) and EaI (HR 2.43, 95% CI 
1.75–3.37) were significantly associated with outcome. At multivariate Cox analysis, only EaI (HR 1.60, 95% CI 1.03–2.50) 
retained statistical significance. An EaI ≥ 4 mmHg/ml/m2 showed 100% sensitivity and 99.4% specificity for predicting 
outcome (AUC = 0.98). In patients with mild-to-moderate IPF, an EaI ≥ 4 mmHg/ml/m2 is a negative prognostic factor over 
a medium-term follow-up.