Three-dimensional echocardiography investigation of the mechanisms of tricuspid annular dilatation

Tricuspid annular (TA) size, assessed by 2D transthoracic echocardiography (TTE), has a well-established prognostic value in patients undergoing mitral valve surgery, with TA dilatation triggering simultaneous tricuspid annuloplasty. While TA dilatation is common in patients with dilated atria secondary to atrial fibrillation, little is known about the mechanisms of TA dilatation in patients with sinus rhythm (SR). This study aimed to identify echocardiographic parameters most closely related to the TA size as a potential tool for identification of patients prone to developing TA enlargement. 120 patients with SR underwent clinically indicated TTE, including 30 patients with normal hearts and 90 patients diagnosed with at least one right heart abnormality, defined as: right ventricular (RV) or right atrial (RA) dilatation, ≥ moderate tricuspid regurgitation (TR) and elevated systolic pulmonary artery pressure (sPAP). RA and RV end-diastolic and end-systolic volumes (EDV, ESV) and function were measured using commercial 3D software (TomTec). 3D RV long and short axes were used as surrogate indices of RV shape. Degrees of TR and sPAP were estimated by 2D TTE. 3D TA sizing was performed at end-diastole using 3D custom software. Linear regression analysis was used to identify variables best correlated with TA size, followed by multivariate analysis to identify independent associations. The highest correlations were found between TA area and: RA ESV (r = 0.73; p < 0.01), RV EDV (r = 0.58; p < 0.01), RV end-diastolic long and short axes (r = 0.53, 0.42; both p < 0.01), TR degree (r = 0.40; p < 0.01) and sPAP (r = 0.32; p < 0.01). Multivariate analysis revealed that RA ESV was the only parameter independently associated with TA area (p < 0.05, r = 0.85). In conclusion, RA volume plays an important role in TA dilatation even in patients with normal SR. Understanding of annular remodeling mechanisms could aid in identifying patients at higher risk for TA dilatation, especially those scheduled for mitral valve surgery.