Multi-center Study of Three-Dimensional Transesophageal Echocardiography in Patients With Secondary Mitral Regurgitation

Three-dimensional transesophageal echocardiography (3D-TEE) enables detailed assessment of mitral valve anatomy, annular geometry, and regurgitation. This prospective multicenter observational study will evaluate atrial secondary mitral regurgitation (A-SMR) using 3D-TEE combined with transthoracic echocardiography. The study aims to characterize regurgitation severity and associated factors and compare mitral valve structure and left ventricular function between patients and controls. It will also investigate echocardiographic predictors of clinical outcomes during follow-up.

Inclusion Criteria: Atrial Secondary Mitral Regurgitation Group: 1. Age 18 years or older. 2. At least mild atrial secondary mitral regurgitation, meeting all of the following criteria: * Structurally normal mitral valve without primary mitral valve disease. * Left ventricular ejection fraction ≥50%, without regional wall motion abnormalities or mitral leaflet tethering. * Normal or mildly enlarged left ventricle, meeting either of the following sex-specific criteria: * Left ventricular end-diastolic diameter \39 mm in men. 3. Undergoing both transthoracic and transesophageal echocardiography, with standardized images retained. Control Group: 1. Age 18 years or older. 2. Undergoing transesophageal echocardiography for clinical indications, such as suspected patent foramen ovale or infective endocarditis. 3. Transthoracic echocardiography showing no significant abnormalities in cardiac structure or function, with less than mild regurgitation of all cardiac valves. All participants must meet the inclusion criteria for their respective group and provide written informed consent. Exclusion Criteria: The following exclusion criteria apply to both groups: 1. Primary mitral regurgitation caused by organic mitral valve disease, including degenerative changes, rheumatic involvement, congenital mitral valve abnormalities, or vegetations. 2. Moderate or greater aortic valve disease. 3. Previous cardiac valve surgery or catheter-based valve intervention. 4. Congenital heart disease. 5. Inadequate three-dimensional transesophageal echocardiographic image quality that precludes reliable assessment of mitral valve structure and motion. 6. Contraindications to, or inability to tolerate, transesophageal echocardiography. 7. Refusal to provide written informed consent.