Transcatheter closure of atrial septal defects: how large is too large?

Transcatheter closure has become an accepted alternative to surgical repair for ostium secundum atrial septal defects (ASD). However, large ASDs (>38 mm) and defects with deficient rims are usually not offered transcatheter closure but are referred for surgical closure. Several studies have reported the feasibility of transcatheter closure in complex cases with a variety of modified implantation methods such as balloon assisted technique (BAT). AA Pillai and co-authors report the transcatheter closure of ASD ≥35 mm with the BAT. However, the true significance of their study is rather in demonstrating the superiority of BAT to conventional technique and other modified implantation techniques in patients with ASD rather than feasiblity of transcatheter closure of large defect. Finally, a single dimension does not reflect the true ASD size because many defects are not round in shape but rather oval or even crescentric. Hence, future studies will need not only to demonstrate the ideal implantation method but also the appropriate 3-dimensional (3D) imaging definition of the defect in this patient population.