A familial cluster of idiopathic dilatation of the right atrium-A two-case report.

We report two cases of idiopathic atrial dilatation in two adult siblings, a brother and a sister. The first patient was a 36-year-old man who was referred to our institution for evaluation of atrial fibrillation and syncopes. Transthoracic echocardiography revealed an enlarged right atrium accompanied by a severe tricuspid regurgitation associated with annular dilatation. The diagnosis of idiopathic atrial enlargement was made after all other lesions known to produce it have been excluded. The patient did not consent to the proposed cardiothoracic surgical treatment so he remained on conservative therapy. On electrocardiography, atrial standstill was noted, resulting in the implantation of a VVI cardiac pacemaker one year later. After an asymptomatic period, the patient suffered sudden death at the age of 40 years. His 45-year-old sister suffering from the same symptoms was also referred for examination, also to be diagnosed with idiopathic atrial dilatation and severe tricuspid regurgitation. Idiopathic dilatation of the right atrium, although a rare disorder, should not be forgotten as differential diagnosis for enlarged right atrium. Transthoracic echocardiography is the most commonly used technique and in our cases it was sufficient for establishing the diagnosis.