An 18-year-old asymptomatic and athletic female was referred to our institute with a high suspicion of a pericardial cyst, seen on a pre-competitive echocardiogram. A cardiovascular magnetic resonance (CMR) with gadolinium was performed. The balanced turbo field-echo sequence in short axis and four-chamber view showed aneurysmal dilation (*) of the right atrial appendage (RAA) measuring 79 × 95 × 52 mm (Fig. 1A and B). The RAA aneurysm changed in size during systole (Fig. 2A) and diastole (Fig. 2B), indicating the presence of contraction. T1-weighted imaging did not demonstrate late gadolinium enhancement along the wall of the RA and RRA aneurysm (Fig. 3) and no clear evidence of thrombosis was seen. Biventricular systolic function was preserved. Due to a low sensitivity of the CMR to rule out small and mobile thrombi, a transesophageal echocardiogram was indicated, however, it was rejected by the patient.
RAA aneurysm is a rare congenital cardiac abnormality thought to be caused by dysplasia of the muscular wall of the RA and RAA1. Most patients are asymptomatic at presentation, however, some present palpitations, arrhythmias, or dyspnea. Complications include atrial tachyarrhythmias and intracavitary thrombus. Final diagnosis can be confirmed on CMR as was done in our case2. Scarce data exist about the management of the RAA aneurysm, therefore, a conservative approach is usually recommended3. In our patient, no significant arrhythmia was seen on 24 h Holter monitoring and because the patient refused to take medication an imaging follow-up was recommended without anticoagulation.