Abstract OBJECTIVES The goal of this study was to identify the risk factors for prolonged length of stay (LOS) in the intensive care unit (ICU) after a bidirectional cavopulmonary shunt (BCPS) procedure and its impact on the number of deaths. METHODS In total, 556 patients who underwent BCPS between January 1998 and December 2019 were included in the study. RESULTS Eighteen patients died while in the ICU, and 35 died after discharge from the ICU. Reduced ventricular function was significantly associated with death during the ICU stay (P = 0.002). In patients who were discharged alive from the ICU, LOS in the ICU [hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.02–1.06; P < 0.001] and a dominant right ventricle (HR 2.41, 95% CI 1.03–6.63; P = 0.04) were independent risk factors for death. Receiver operating characteristic analysis identified a cut-off value for length of ICU stay of 19 days. Mean pulmonary artery pressure (HR 1.03, 95% CI 1.01–1.05; P = 0.04) was a significant risk factor for a prolonged ICU stay. CONCLUSIONS Prolonged LOS in the ICU with a cut-off value of 19 days after BCPS was a significant risk factor for mortality. High pulmonary artery pressure at BCPS was a significant risk factor for a prolonged ICU stay.