TAPSE/SPAP ratio stratifies mortality risk in mild-to-moderate idiopathic pulmonary fibrosis

BACKGROUND: Due to paucity of literature data, we aimed at evaluating the prognostic role of the ratio of tricuspid annular plane systolic excursion (TAPSE) to systolic pulmonary artery pressure (SPAP) in idiopathic pulmonary fibrosis (IPF) patients without severe pulmonary hypertension and at assessing its correlation with effective arterial elastance index (EaI). METHODS: Multi-instrumental data obtained in 60 IPF patients (73.2 ± 6.8 years) and 60 matched controls were retrospectively analysed. Primary endpoint was all-cause mortality, while secondary endpoint was the composite of all-cause mortality and re-hospitalisations for all-causes over medium-term follow-up. RESULTS: ;At baseline, TAPSE/SPAP was significantly lower in patients with IPF than in controls (0.36 ± 0.25 vs. 0.77 ± 0.18 mm/mmHg; P < 0.001). TAPSE/SPAP was inversely correlated with EaI (r = -0.96) in IPF patients. During follow-up (3.5 ± 1.5 years), 21 patients died and 25 were re-hospitalised due to cardiopulmonary causes. TAPSE/SPAP was independently associated with both primary (HR 0.79, 95%CI 0.65-0.97) and secondary (HR 0.94, 95%CI 0.92-0.97) endpoints. A TAPSE/SPAP ratio of <0.20 and <0.44 mm/mmHg showed the greatest sensitivity and specificity for predicting primary (AUC 0.98) and secondary (AUC 0.99) endpoints, respectively. CONCLUSIONS: TAPSE/SPAP is a strong predictor of adverse outcomes in mild-to-moderate IPF. The strong correlation between TAPSE/SPAP and EaI might be an expression of a systemic fibrotic process which involves the heart, lungs and circulation.