Incidence
Due to its rarity, the true incidence with either usual or mirror-imaged atrial arrangement, or in association with isomerism of the atrial appendages, is difficult to establish. The incidence in patients with congenital heart diseases was reported as 0.2% in necropsy studies,7,18,23,37-42,63-66 0.5%-0.98% in echocardiographic series,11,21 and 1.7% when using computed tomography.4,19,41,71 Its occurrence without any associated cardiac or aortic arch anomaly is extremely rare. Its prevalence is estimated at 0.02%.14-17,33