Background: Idiopathic pulmonary fibrosis (IPF) is frequently complicated by pulmonary vascular involvement and right ventricular (RV) dysfunction, both of which adversely affect prognosis. The relationship between impaired gas exchange and echocardiographic indices of RV function, particularly the TAPSE/PAPs (tricuspid annular plane systolic excursion/systolic pulmonary artery pressure) ratio as a marker of RV–pulmonary arterial (RV–PA) coupling, has not been fully characterized. Methods: We retrospectively evaluated 198 consecutive patients with IPF assessed at a single tertiary referral center between 2020 and 2026; 188 with complete pulmonary function testing were included in the main analyses. The primary exposure was gas exchange, measured by single-breath DLCO% (diffusing capacity of the lung for carbon monoxide) and stratified into four categories (Normal ≥ 80%, n = 21; Mild 60–79%, n = 56; Moderate 40–59%, n = 70; Severe < 40%, n = 41). The main outcome measures were echocardiographic indices of RV function—TAPSE, systolic pulmonary artery pressure (PAPs), and the TAPSE/PAPs ratio. Associations were assessed using Pearson’s correlation, one-way ANOVA, and multivariable linear regression adjusted for age, sex, and smoking status, with the Mild group as the reference for categorical analyses. Results: Lower DLCO values were independently associated with higher PAPs (adjusted β = −0.24 mmHg per 1% DLCO, p = 0.004) and with a lower TAPSE/PAPs ratio (adjusted β = +0.005 per 1% DLCO, p = 0.040). Compared with the Mild reference group, patients with Severe DLCO reduction had markedly higher PAPs (+14.6 mmHg, p = 0.002) and a lower TAPSE/PAPs ratio (−0.37, p = 0.002), with attenuated findings in the Moderate category; the small Normal group did not differ significantly from the Mild one. TAPSE alone showed only a weak, non-significant trend (r = 0.195, p = 0.083). Conclusions: In patients with IPF, lower DLCO was independently associated with higher pulmonary artery pressure and, to a lesser extent, with reduced RV–PA coupling (a lower TAPSE/PAPs ratio), whereas RV longitudinal systolic function (TAPSE) appeared preserved. Among pulmonary function parameters, DLCO showed the strongest association with PAPs. In this exploratory, cross-sectional analysis, combined evaluation of DLCO and the TAPSE/PAPs ratio may help characterize right heart involvement in IPF; its value for pulmonary hypertension (PH) screening requires prospective confirmation.

Background: The hemoglobin-to-red cell distribution width ratio (HRR) is a composite hematologic biomarker that integrates oxygen-carrying capacity and inflammation-related erythrocyte variability. Its prognostic value in idiopathic pulmonary fibrosis (IPF), and its relationship with right ventricular (RV) function, have not been established. Methods: We conducted a single-center retrospective study of 198 patients with IPF. A total of 165 patients with baseline hemoglobin, red cell distribution width (RDW) and date of diagnosis available constituted the analytical cohort. An HRR cutoff (≤0.86) was derived by time-dependent Receiver Operating Characteristic (ROC) curve analysis at 5 years. All-cause mortality from diagnosis was assessed by Kaplan–Meier and Cox regression, with bootstrap internal validation. Associations between hematologic markers and TAPSE (Tricuspid Annular Plane Systolic Excursion), PAPs (pulmonary arterial systolic pressure) and TAPSE/PASP were examined by linear and logistic regression, followed by joint stratification of HRR and RV–PA coupling. Results: Over a median follow-up of 70.3 months, 57 patients (34.5%) died. Low HRR was associated with higher mortality (72.7% vs. 15.5%; adjusted HR 3.07, 95% CI 1.68–5.63; optimism-corrected HR 2.37) and improved a clinical model beyond RDW (likelihood-ratio p = 0.012). HRR was not associated with TAPSE, PAPs, TAPSE/PASP or RV–PA uncoupling. In exploratory joint stratification, mortality rose from 11.7% with both markers preserved to 100% with both abnormal (age-adjusted HR 6.47, 95% CI 2.64–15.86). At 5 years, HRR and RDW showed similar discrimination (time-dependent AUC 0.70 and 0.71), higher than TAPSE/PASP (0.61). Conclusions: HRR is a simple, inexpensive and independent predictor of mortality in IPF that is unrelated to RV–PA coupling. The two markers provide complementary prognostic information, and their combination identifies a subgroup at very high risk. These findings require external validation.