Persistent symptoms and long-term complications in the setting of Fontan circulation (FC) (systemic ventricular failure, etc) still remain as significant clinical challenges in clinical practice.1 In their recently published interesting article,2 Ridderbos et al have suggested pulmonary artery (PA) size (as measured with Nakata index) as an independent predictor for functional clinical status (defined as peak oxygen consumption) in Fontan patients. The authors should be congratulated for the design and novel findings of the study. However, we would …