We herein report a 61-year-old woman with a history of mitral valve replacement for rheumatic fever who presented with crural edema and ascites. Computed tomography showed massive left atrial (LA) calcification involving the interatrial septum, termed "coconut atrium." Catheterization revealed not only pulmonary artery hypertension but also a large V-wave in the pulmonary artery wedge pressure waveform and a dip-and-plateau pattern of right ventricular pressure. Three-dimensional transthoracic echocardiography confirmed the early attainment of peak LA volume and a decreased LA expansion index. Stiff LA syndrome due to coconut LA results in the development of restrictive right ventricular physiology.
Keywords: coconut atrium; dip-and-plateau; left atrial calcification; left atrial expansion index; right ventricular restrictive physiology; stiff left atrial syndrome.