We sought to evaluate extracorporeal membrane oxygenation (ECMO) use for low cardiac output syndrome (LCOS) following congenital heart surgery. Our primary aims were: (1) To compare hospital mortality and morbidity for proactive ECMO versus extracorporeal cardiopulmonary resuscitation (ECPR). (2) To assess the impact of CPR duration. Our secondary aim was to investigate pre-ECMO vasoactive inotropic scores (VIS).