Significance of strictly defined idiopathic tricuspid regurgitation

Background: Moderate to severe tricuspid regurgitation (TR) is known to cause right ventricular (RV) failure and death. Although TR is traditionally classified as primary or secondary, recently, a new class of TR called idiopathic TR has been proposed, with varying definitions among different studies. Methods: The data were retrospectively collected for the period of January to June 2018 for 8711 patients from the patient cohort of the National Cheng Kung University Hospital echocardiography laboratory. A total of 670 patients (7.7%) with moderate-to-severe TR were included. Idiopathic TR was diagnosed strictly using a new systematic approach. Results: The distribution of significant TR included 74 (11.0%) primary TR cases, 48 (7.2%) with pacemaker-related TR, 267 (39.9%) with left heart disease, 24 (3.6%) with congenital heart disease, 6 (0.9%) with RV myopathy, 105 (15.7%) with pulmonary hypertension, and 146 (21.8%) with idiopathic TR. The mean age in primary and idiopathic TR groups was older (p = 0.004), with lower estimated pulmonary pressure (p < 0.001), higher RV fraction area change (FAC, p < 0.001), and tricuspid annulus systolic velocity (S', p = 0.004) compared with functional TR group. Multivariate analysis showed that idiopathic TR (p = 0.002) and primary TR (p = 0.008) had better RV FAC than functional TR. Conclusion: Idiopathic TR was associated with better RV function than the other secondary TRs. Thus, idiopathic TR should be strictly defined and regarded as a distinct type of TR.