Abstract 11938: Mechanisms of Significant Functional Tricuspid Regurgitation in Pulmonary Arterial Hypertension

Abstract

Introduction: The relationship between pulmonary arterial hypertension (PAH) and secondary (or functional) tricuspid regurgitation (STR) is well-established, and the simultaneous presence of both conditions portends particularly poor outcomes. Yet not all patients with PAH develop significant STR, and the mechanisms underlying this phenomenon remain unclear. Methods: From the Cleveland Clinic Pulmonary Hypertension Registry, patients diagnosed with PAH between 2007-2013 were included. STR, defined by absent primary tricuspid valve disease on transthoracic echocardiogram (TTE), was considered significant if ≥moderate in severity (≥2+ grade) on TTE. Right-sided chambers, annular, and valvular anatomic and functional characteristics by cardiac computed tomography and TTE were compared between patients with significant vs. nonsignificant STR. Results: Among 88 included patients, 52 had significant STR. The median age was 57 years, and 78% were female. No differences were observed in all baseline clinical characteristics between groups. Relative to those with nonsignificant STR, patients with significant STR had worse right ventricular (RV) dysfunction as evidenced by lower tricuspid annular planar systolic excursion [1.5 (1.3,1.7) vs 2.1 (1.7,2.4); p=0.02] and fractional area change, and worse RV global longitudinal strain and RV free wall strain. Significant STR was further associated with increased RV sphericity as denoted by a smaller sphericity index [1.8 (1.6,2.1) vs. 2 (1.7,2.5); p=0.004], with similar annular dimensions and shape, mural and septal leaflets’ length and angle, and tenting height. Conclusion: Anatomic and functional alterations in the RV rather than in the tricuspid valve are implicated in the development of STR in patients with PAH. The underlying mechanism may be linked to RV dyfunction and remodeling, via increasing RV size and sphericity.