Right heart chambers geometry and function in patients with the atrial and the ventricular phenotypes of functional tricuspid regurgitation

Aims: Atrial functional tricuspid regurgitation (A-FTR) is a recently defined phenotype of functional tricuspid regurgitation (FTR) associated with persistent/permanent atrial fibrillation. Differently from the classical ventricular form of FTR (V-FTR), patients with A-FTR might present with severely dilated right atrium and tricuspid annulus (TA), and with preserved right ventricular (RV) size and systolic function. However, the geometry and function of the right ventricle, right atrium, and TA in patients with A-FTR and V-FTR remain to be systematically evaluated. Accordingly, we sought to: (i) study the geometry and function of the right ventricle, right atrium, and TA in A-FTR by two- and three-dimensional transthoracic echocardiography; and (ii) compare them with those found in V-FTR.

Methods and results: We prospectively analysed 113 (44 men, age 68 ± 18 years) FTR patients (A-FTR = 55 and V-FTR = 58) that were compared to two groups of age- and sex-matched controls to develop the respective Z-scores. Severity of FTR was similar in A-FTR and V-FTR patients. Z-scores of RV size were significantly larger, and those of RV function were significantly lower in V-FTR than in A-FTR (P < 0.001 for all). The right atrium was significantly enlarged in both A-FTR and V-FTR compared to controls (P < 0.001, Z-scores > 2), with similar right atrial (RA) maximum volume (RAVmax) between A-FTR and V-FTR (P = 0.2). Whereas, the RA minimum volumes (RAVmin) were significantly larger in A-FTR than in V-FTR (P = 0.001).

Conclusion: Despite similar degrees of FTR and RAVmax size, A-FTR patients show larger RAVmin and smaller TA areas than V-FTR patients. Conversely, V-FTR patients show dilated, more elliptic and dysfunctional right ventricle than A-FTR patients.