Outcomes of the Arterial Switch Operation in ≤2.5-kg Neonates

Although low birth weight is a known risk factor for mortality in congenital heart lesions and may consequently delay surgical repair, outcomes in low-weight neonates undergoing the arterial switch operation (ASO) have not been well described. Our objective was to assess the safety of this procedure in infants weighing ≤2.5 kg at the time of surgery. We retrospectively analyzed outcomes for all neonates undergoing the ASO at our institution from 2005 to 2015. Our primary outcome of interest was major morbidity or operative mortality, assessed as a composite outcome. From 2005 to 2015, 217 neonates underwent the ASO, with 31 (14%) weighing ≤2.5 kg at the date of surgery, and 8 weighing <2.0 kg. Neonates weighing ≤2.5 kg were more likely to be premature than those weighing >2.5 kg, but there was no difference in the age at operation between these groups. Overall, 32 infants experienced a major morbidity or mortality, including 37.5% (n = 3) weighing <2.0 kg, 8.7% (n = 2) weighing 2.0-2.5 kg, and 14.5% (n = 7) weighing >2.5 kg (P = 0.141). One infant weighing <2.0 kg (1.1 kg) and 4 infants weighing >2.5 kg died. In multivariable models, odds of major morbidity or mortality were significantly higher for infants weighing <2 kg compared with infants weighing >2.5 kg (odds ratio 3.93, 95% confidence interval 1.04-14.85, P = 0.044), but there was no difference between infants weighing 2.0-2.5 kg and those weighing >2.5 kg (P = 0.225). The ASO can be performed safely in 2.0- to 2.5-kg neonates and yields results comparable with higher weight infants. Imposed delays for corrective surgery may not be necessary for these low-weight infants with transposition of the great arteries.