Patient: Male, 76Final Diagnosis: Rheumatic valvular heart diseaseSymptoms: Breathlessness and leg edemaMedication: —Clinical Procedure: Medical treatment for heart failureSpecialty: CardiologyObjective:Rare diseaseBackground:Complete calcification of the left atrium (LA) is called “coconut atrium”, which decreases the compliance of LA, leading to the elevation of LA pressure that is transmitted to the right-side of the heart. The pathogenesis of LA calcification in patients with rheumatic heart disease is unknown; however, possible mechanisms include chronic strain force in the atrial wall and inflammation. We report here a patient with long-standing rheumatic valvular heart disease with coconut atrium.Case Report: A 76-year-old man presented with breathlessness and leg edema due to right-sided heart failure. He was diagnosed with rheumatic fever at 8 years of age. Mitral commissurotomy and the mitral and aortic valve replacement were previously performed to treat mitral and aortic valvular stenosis. The profile view of the chest X-ray indicated a diffuse calcified outline of the LA wall. A transthoracic echocardiogram revealed pulmonary hyper-tension and dilatation of both atria. Moreover, computed tomography showed nearly circumferential calcification of the LA wall. Despite intense medical treatment, he succumbed to heart failure. An autopsy demonstrated that the LA was markedly dilated, its wall was calcified, and its appearance was similar to the surface of an atherosclerotic aorta. Microscopic examination revealed intensive calcification in the endocardium. Minimal accumulation of inflammatory cells was noted. Although slight fibrosis was observed, the cardiac musculature was preserved.Conclusions:To the best of our knowledge, this is the first report that identifies the histological changes of LA calcification associated with long-standing rheumatic valvular heart disease.