To the editor: We read with great interest the article by Balint and coworkers,1 in which they reported the results of catheter closure of an atrial septal defect (ASD) in 54 patients with associated pulmonary arterial hypertension (PAH). The authors described, on the one hand, successful closure and a decrease in pulmonary artery pressure and New York Heart Association (NYHA) functional class at 1 year follow-up in the majority of patients. On the other hand, more than half of the patients had persistent PAH (moderate or severe) after closure and two patients died during follow-up. The authors’ interpretation of these data is that catheter closure of ASD in patients with PAH is successful and has a good outcome. In our opinion, however, this conclusion is not justified and we feel that it is important to add some considerations on PAH associated with congenital pulmonary-to-systemic shunts, in order to put …