Idiopathic dilatation of the right atrium

A 66-year-old woman was referred to our institution suffering from progressive dyspnoea and asthenia. Her medical history included palpitations without cardiac investigation. She presented clinical manifestations of right-sided heart failure. Auscultation revealed a systolic murmur of tricuspid regurgitation. EKG recorded sinus rhythm with a complete right bundle branch block. Chest radiography showed a cardiac enlargement (cardiothoracic index of 0.74; Panel A). Echocardiogram demonstrated a highly enlarged right atrium, a functional tricuspid regurgitation, and a dilated right ventricle. The left cavities were compressed by the right cavities (Panel B). Systolic pulmonary artery pressure was estimated at 45 mmHg. Agitated saline injection did not show atrial shunt. Idiopathic dilatation of the right atrium (IDRA) was diagnosed. Magnetic resonance imaging confirmed the echocardiographic findings and the volume of the right atrium was measured at 700 mL (Panel C). The patient refused further extensive examinations. She was discharged with diuretics. IDRA must be evoked on the finding of a disproportionately enlarged right atrium in the absence of other cardiac or haemodynamic abnormalities and must be distinguished from other anomalies such as right atrial diverticula or Ebstein's anomaly. Right atrial enlargement may be associated with tricuspid annular dilation responsible for functionnal regurgitation, which may worsen the right atrium dilation and led to right ventricular dysfunction. IDRA has been reported to occur at all stages of life and is often diagnosed fortuitously. Atrial fibrillation, systemic embolism, and heart failure are the classical complications that can be managed medically in most of the cases. Surgical resection of the right atrium may be proposed in patients with incessant arrhythmia, congestive heart failure, and left ventricular compression that might cause sudden cardiac death. Panel A. Chest radiography: cardiac enlargement with a cardiothoracic index of 0.74 and slight congestion of the bilateral lung fields. Panel B. An enlarged right atrium with severe functional tricuspid regurgitation, dilated hypokinetic right ventricle, and compression of the left cavities by the right cavities. Panel C. Magnetic resonance imaging: a highly enlarged right atrium with a volume measured at 700 mL.