['Studies on intracardiac echocardiography for transcatheter closure of secundum atrial septal defect (ASD) only include ASDs ≤38mm diameter without rim deficiency.', 'To assess transcatheter closure of complex ASDs under intracardiac echocardiography guidance.', 'Retrospective study from January 2006 to January 2012 in all consecutive adult patients referred to our centre for percutaneous device closure of ASD. Complex cases were defined as defect>38mm and/or defect with rim deficiency other than the anterior-superior rim.', 'Transcatheter closure was performed in 93 consecutive adult patients (59 women) with a median age of 48 (18-88) years. Complex cases comprised 17 patients (18%) with a median age of 54 (20-81) years and a median weight of 58 (45-99) kg. Thirteen cases had one or more deficient rims other than the anterior-superior rim, whereas nine had an ASD size>38mm. Transcatheter closure was successful in 14 cases, whereas three cases failed (18%). Minor complications occurred in three patients (18%). All the other non-complex ASDs were successfully closed percutaneously. Among the 93 patients, rim deficiency other than the anterior-superior rim tended to be associated with failure of transcatheter closure (P=0.058).'] Is transcatheter closure of complex atrial septal defects efficient under intracardiac echocardiographic guidance?