THE RIGHT HEART IN IDIOPATHIC PULMONARY FIBROSIS: IMPACT OF AGE AT DIAGNOSIS ON RIGHT VENTRICULAR–ARTERIAL COUPLING AND ON PROGNOSIS.

Introduction. Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing lung disease of unknown cause, which mainly affects older adults and whose prognosis depends not only on the progression of fibrosis, but also on the involvement of the pulmonary circulation and of the right ventricle. Age is a recognised determinant of survival, included in the GAP index, whereas it is much less clear how the right ventricle responds, as age advances, to the increased load imposed by the pulmonary circulation. This study assessed the association of age at diagnosis with right heart function and with mortality, focusing on the coupling between the right ventricle and the pulmonary circulation. Materials and methods. A total of 198 patients with IPF followed at the University Hospital of Modena were included in an ambispective observational study, with data collected in a dedicated database. Right ventricular function was assessed by tricuspid annular plane systolic excursion (TAPSE), vascular load by systolic pulmonary artery pressure (PAPs), and their coupling by the TAPSE/PAPs ratio. Patients were grouped by age at diagnosis (<65, 65–74 and ≥75 years). In all regression models, adjusted for sex and smoking, age was analysed as a continuous variable; in the mortality analysis it was also dichotomised at 65 years. Further models included both age and carbon monoxide diffusing capacity (DLCO). Results. Mean age at diagnosis was 72.3 ± 8.2 years, with a male predominance (84.3%), and 55 patients (27.8%) died over a median follow-up of 44.6 months. No cross-sectional association was demonstrable between age at diagnosis and the severity of functional impairment, because lung function and echocardiographic parameters were similar across the three age groups, although a trend towards lower DLCO values was observed in older patients (ρ = −0.126; p = 0.086). After adjustment for sex and smoking, however, older age was independently associated with a lower TAPSE/PAPs ratio, available in 71 patients (β = −0.010 per year; p = 0.034), corresponding to a reduction of about 0.10 mm/mmHg every ten years, and the association persisted when DLCO was included in the model (β = −0.011; p = 0.019). No such association was found for TAPSE or PAPs alone. The association between age and survival was not gradual, since the year-by-year increase in risk was only borderline, whereas patients diagnosed at 65 years or older showed a markedly higher probability of death (OR 8.00; 95% CI 1.83–34.98; p = 0.006). Patients who died were not older (p = 0.203), but had a worse cardiopulmonary profile, with a TAPSE/PAPs ratio of 0.41 ± 0.25 compared with 0.70 ± 0.35 in survivors (p < 0.001). When age and DLCO were considered together, DLCO remained the stronger predictor both of PAPs (p = 0.002) and of death (OR 0.98; p = 0.011), while age was independently associated only with the TAPSE/PAPs ratio. Conclusion. In this cohort, patients diagnosed at an older age did not show a greater impairment of lung function but showed a reduced coupling between the right ventricle and the pulmonary circulation. Among the echocardiographic measures, only the TAPSE/PAPs ratio decreased independently with age, whereas TAPSE and PAPs alone did not. The ratio was also markedly lower in the patients who died, while DLCO remained the stronger prognostic marker in the cohort. The TAPSE/PAPs ratio, obtained from the echocardiographic assessment of the right heart, therefore adds information on right ventricular adaptation in older patients that pulmonary function tests alone do not provide. Larger prospective multicentre studies are needed to confirm these findings and to establish whether the systematic assessment of the TAPSE/PAPs ratio can improve the cardiological surveillance of these patients.