Case Report: Transthoracic echocardiographic diagnosis of agenesis of mitral chordae tendineae with papillary muscle fusion.

The complete absence of mitral valve chordae tendineae together with fusion of the papillary muscles constitutes an exceedingly uncommon congenital anomaly, seldom encountered in clinical practice and prone to diagnostic oversight. We describe an adult patient in whom transthoracic echocardiography (TTE) provided definitive preoperative identification of the malformation, later corroborated by direct surgical inspection. The 50-year-old man presented with progressive exertional dyspnea and atrial fibrillation. Comprehensive TTE revealed redundant mitral leaflets inserting directly onto fused papillary muscles along the posterior left-ventricular wall, with total absence of the subvalvular chordal apparatus, resulting in severe mitral stenosis, moderate-to-severe regurgitation, secondary tricuspid regurgitation, and pulmonary hypertension. Mechanical mitral valve replacement and tricuspid annuloplasty yielded an uneventful recovery. This report underscores TTE's pivotal role in delineating the full mitral apparatus and refines the diagnostic framework for this rare entity.