These patients with worsening BNP levels at 3 months were more likely to have PAH associated with congenital heart disease or PAH/CTEPH combined with left heart disease (28.6% and 28.6%, respectively), were in WHO-FC III (71.4%), and most (92.9%) had an elevated BNP level (>50 ng/L) at baseline. Here, NPPB is linked to congenital heart disease.