Infants were randomly assigned to either the MBT shunt or the RVPA shunt within strata according to the presence or absence of aortic atresia and obstructed pulmonary venous return, with dynamic allocation by the surgeon.23 (link) The primary outcome was the rate of death or cardiac transplantation 12 months after randomization. Secondary outcomes included morbidity during the Norwood and stage II hospitalizations; the incidence of unintended cardiovascular interventions involving the shunt, pulmonary arteries, or neoaorta by 12 months; right ventricular function, right ventricular volume, and the degree of tricuspid-valve regurgitation at discharge after the Norwood procedure, before stage II, and at the age of 14 months on the basis of echocardiograms interpreted by the core laboratory; and the core laboratory interpretation of pulmonary-artery size by angiography before stage II. The right ventricular volumes and ejection fractions were calculated with the use of the biplane pyramidal method.24 (link)
Safety during the first 12 months after randomization was monitored with the use of three measurements: the rate of composite serious adverse events (death, acute shunt failure, cardiac arrest, extracorporeal membrane oxygenation, unplanned cardiovascular reoperation, or necrotizing enterocolitis), the rate of composite serious adverse events with death excluded, and the rate of other complications. The prespecified subgroups for analysis were as follows: birth weight (<2500 or ≥2500 g), preoperative tricuspid-valve regurgitation (proximal jet width, <2.5 or ≥2.5 mm), deep hypothermic circulatory arrest versus regional cerebral perfusion, the surgeon’s annual experience in performing Norwood procedures in infants randomly assigned to this procedure (<6, 6 to 10, 11 to 15, or >15 procedures), and the annual volume of Norwood procedures at each center (<11, 11 to 25, 26 to 40, or >40 procedures). The protocol was approved by each center’s institutional review board, and written informed consent was obtained from a parent or guardian.
Safety during the first 12 months after randomization was monitored with the use of three measurements: the rate of composite serious adverse events (death, acute shunt failure, cardiac arrest, extracorporeal membrane oxygenation, unplanned cardiovascular reoperation, or necrotizing enterocolitis), the rate of composite serious adverse events with death excluded, and the rate of other complications. The prespecified subgroups for analysis were as follows: birth weight (<2500 or ≥2500 g), preoperative tricuspid-valve regurgitation (proximal jet width, <2.5 or ≥2.5 mm), deep hypothermic circulatory arrest versus regional cerebral perfusion, the surgeon’s annual experience in performing Norwood procedures in infants randomly assigned to this procedure (<6, 6 to 10, 11 to 15, or >15 procedures), and the annual volume of Norwood procedures at each center (<11, 11 to 25, 26 to 40, or >40 procedures). The protocol was approved by each center’s institutional review board, and written informed consent was obtained from a parent or guardian.