Abstract OBJECTIVES The present study was aiming to determine whether high mean pulmonary artery pressure before bidirectional cavopulmonary shunt is a risk factor for late adverse events in patients with low pulmonary artery pressure before total cavopulmonary connection (TCPC). METHODS We retrospectively reviewed the medical records of all patients undergoing both bidirectional cavopulmonary shunt and TCPC with available cardiac catheterization data. RESULTS A total of 316 patients were included in this study. The patients were divided into 4 groups according to mean pulmonary pressure: those with pre-Glenn <16 mmHg and pre-Fontan <10 mmHg (Group LL, n = 124), those with pre-Glenn ≥16 mmHg and pre-Fontan <10 mmHg (Group HL, n = 61), those with pre-Glenn <16 mmHg and pre-Fontan ≥10 mmHg (Group LH, n = 66) and those with pre-Glenn ≥16 mmHg and pre-Fontan ≥10 mmHg (Group HH, n = 65). Group HL showed significantly higher rate of adverse events after TCPC than Group LL (P = 0.02). In univariate linear analysis, a history of atrial septectomy at stage 1 palliation was associated with low pre-Glenn mean pulmonary artery pressure (Coefficient B −1.38, 95% confidence interval −2.53 to −0.24; P = 0.02), while pulmonary artery banding was a significant risk factor for elevated pre-Fontan mean pulmonary artery pressure (Coefficient B 1.68, 95% confidence interval 0.81 to 2.56, P < 0.001). CONCLUSIONS High mean pulmonary artery pressure before bidirectional cavopulmoary shunt (≥16mmHg) remains a significant risk factor for adverse events after TCPC even though mean pulmonary artery pressure decreased below 10 mmHg before TCPC.