This record contains raw data related to the article "Tricuspid annular dilation in patients undergoing early mitral valve surgery: is it an old story?" Patients with mitral valve prolapse (MVP), undergoing early surgery for severe regurgitation, are usually characterized by<br> a low degree of right chambers’ remodeling. In this selected population, the mechanisms leading to tricuspid annular (TA)<br> dilatation (TAD) are not well understood. In this setting, we aimed to evaluate, using three-dimensional echocardiography<br> (3DE), how right chambers affect TA size and might contribute to functional tricuspid regurgitation (FTR) progression.<br> We studied 159 patients treated with early isolated surgery for MVP, characterized by: sinus rhythm; normal biventricular<br> function; normal or elevated pulmonary artery pressure; tricuspid regurgitation (TR) ≤ mild; no concomitant cardiac disease.<br> All patients reached a 3-year echocardiographic follow-up. Based on two-dimensional echocardiography, patients were<br> divided in Group 1 (N = 68, 43%, TAD, TA ≥ 21 mm/m2) and Group 2 (N = 91, 57%, no TAD, TA &lt; 21 mm/m2). By 3DE,<br> Group 1 showed larger TA size, right atrial (RA) volume and right ventricular (RV) conical remodeling compared to Group<br> 2 (p &lt; 0.05). The multivariate analysis revealed that RA volume, RV basal diameter and function were independently correlated<br> to TA size (p &lt; 0.05). At the 3-year follow-up there was a low incidence of FTR, with a trend towards FTR progression<br> in Group 1 (p = 0.07). In patients undergoing early surgery for MVP, TAD seems to result from distinctive early-onset<br> geometrical changes of the right chambers, preceding TR, RV dilatation and pulmonary hypertension at rest. An integrated<br> approach, including right chambers’ assessment by 3DE, might help to better recognized patients at higher risk for TAD<br> and, potentially for FTR.