Abstract
A giant left atrium (GLA) is a challenging manifestation of advanced mitral valve disease, often necessitating mitral valve surgery via median sternotomy due to the anatomical distortion it causes. We present the case of a 50-year-old male patient with New York Heart Association (NYHA) class IV symptoms secondary to severe mitral regurgitation, found to have a left atrial diameter of 17.1 cm, to our knowledge, one of the largest ever reported. After declining sternotomy, the patient underwent successful minimally invasive mitral valve replacement. Despite significant anatomical challenges, the procedure was completed uneventfully through careful preoperative planning and specialized intraoperative techniques. While sternotomy remains standard in such complex presentations, advances in imaging, instrumentation, and surgical expertise are redefining procedural boundaries. This case demonstrates that minimally invasive mitral valve replacement can be safe, feasible, and effective even in patients with extreme atrial enlargement when performed by experienced teams.