Prenatal Diagnosis of Transposition of the Great Arteries Reduces Postnatal Mortality: A Population-Based Study

Background: Transposition of the great arteries (TGA) may present as a life-threatening neonatal malformation. Although prenatal detection facilitates the perinatal management, the impact on outcome is controversial. Methods: This study reviewed the differences in prenatal diagnosis of TGA from 2009 to 2014 among the 5 geographic areas in Ontario and compared the management, morbidity, and mortality among neonates with a prenatal (prenatal cohort; n = 70) vs a postnatal (postnatal cohort; n = 76) anomaly diagnosis. Cases were identified from prospective databases of the provincial cardiac tertiary centres and the coroner's office. Results: Prenatal TGA detection rates varied significantly among areas (median: 50%; range: 14% to 72%; P = 0.03). Compared with the postnatal cohort, time from birth to tertiary care admission (1.4 vs 10.4 hours, P < 0.001), prostaglandin therapy (0.1 vs 5.3 hours; P < 0.001), balloon atrial septostomy (5.3 vs 14.9 hours; P <0.001), and arterial switch operation (6 vs 9 days, P = 0.002) was significantly shorter in the prenatal cohort. Although other preoperative variables-including the need of ventilation and mechanical support, morbidity score, and lowest pH and preductal oxygen saturations-were comparable, a prenatal diagnosis was associated with improved 1-year survival (odds ratio: 0.108; 95% confidence interval, 0.013-0.88; P = 0.0184). Conclusions: Prenatal diagnosis of TGA significantly shortened time intervals from birth to neonatal care and surgery and was associated with improved survival. The prenatal detection rate of TGA in Ontario was low (50% or less) outside of Metropolitan Toronto, suggesting the need for new strategies to further improve intraprovincial detection rates.