Neurocognitive impairments are frequent in congenital heart disease. The Boston Circulatory Arrest Study (BCAS) is a randomized trial comparing the developmental and neurological outcomes of newborns born with d-transposition of the great arteries (d-TGA) who underwent the arterial switch operation (ASO) with predominantly either deep hypothermic circulatory arrest (DHCA) or continuous low-flow bypass (LFBP) as the method of vital organ support. We report the neuropsychological and structural brain MRI findings of this cohort at adulthood.

Adults with d-TGA enrolled at birth in the BCAS study underwent a neuropsychological evaluation including IQ, executive function, social cognition, and memory functioning. A structural brain MRI was conducted on a Siemens Skyra 3 T with a 64-channel head coil. Focal and multifocal brain abnormalities were recorded including brain mineralization/iron deposits and abnormal T2 hyperintensities (≥ 3 mm) in subcortical grey, periventricular, and deep white matter. d-TGA outcomes were compared to population norms or to a control group.

Eighty-seven adults (28.9 ± 1.3 y, mean age ± SD) participated. Their mean scores were not significantly lower compared to population norms except for working memory (9.2 ± 2.6, P = 0.01), visual social cognition (9.1 ± 2.9, P = 0.01), and reading comprehension (97.2 ± 10.8, P = 0.02). Adults who had been randomly assigned to predominant DHCA vs. LFBP during the neonatal ASO had lower scores on working memory (8.7 ± 2.6 vs. 9.8 ± 2.6, P = 0.04), cognitive flexibility (9.2 ± 2.9 vs. 10.8 ± 2.4, P = 0.01), and social cognition (25.9 ± 5.3 vs. 28.0 ± 4.4, P = 0.05) after adjustment for childhood socioeconomic class and ventricular septal defect status. Structural brain MRI findings included data from 69 adults with d-TGA and 38 controls. Compared to controls, the d-TGA group had greater prevalence of focal and multifocal abnormalities including brain mineralization/iron deposits (41% vs. 3%) and T2 hyperintensities (28% vs. 3%). Congenital brain abnormalities were also more common in the d-TGA group (13% vs. 0%).

Adults with d-TGA have vulnerabilities in working memory, social cognition, and reading abilities. Structural brain abnormalities are prevalent. Follow-up into later adulthood should evaluate the risk of early neurodegenerative processes.