Perinatal changes in ventricular mechanics in transposition of the great arteries: a prospective longitudinal...

Transposition of the great arteries (TGA) is characterized by parallel circulation dependent on intercirculatory mixing. The impact of perinatal hemodynamic changes on myocardial mechanics remains poorly understood. The main objective of the study was to evaluate perinatal changes in ventricular strain in TGA.

The current prospective longitudinal study included 79 fetuses, of whom 72 were included after applying predefined exclusion criteria (19 with simple TGA and 53 healthy controls). Speckle-tracking echocardiography was used to assess segmental and global ventricular strain. Differences in temporal changes between groups were analyzed using linear regression models with robust standard errors clustered at the subject level. Estimated marginal means (EMMS) with 95% confidence intervals (CI) were derived to compare groups at each timepoint (T0: fetal evaluation; T1:neonatal evaluation).

Fetal myocardial deformation parameters did not differ significantly between the TGA and control groups (p > 0.05, corrected p > 0.05). Between-group differences at the neonatal assessment are nominally significant for the basal, medial, and apical interventricular septal segments and for right ventricle (RV) peak longitudinal strain from 4 chamber view (p < 0.05). After Benjamini-Hochberg correction, however, only the medial interventricular septal strain remained statistically significant (p-corrected = 0.0242). Additionally, RV end-systolic volume measured at neonatal time point was significantly increased in neonates with TGA compared to healthy controls [EMMS: 2.50 mL (95% CI: 2.25-2.76) vs. 1.30 mL (95% CI: 1.19-1.41)] reflecting altered loading conditions. Although RV peak longitudinal strain from 4 chamber view significantly differed between neonates requiring balloon atrial septostomy and those who did not (p = 0.007), no significant discriminatory ability was observed (AUC = 0.73, 95% CI: 0.46-1). As secondary outcomes, these parameters were not subject to correction for multiple testing.

In this cohort of prenatally diagnosed simple TGA, fetal myocardial deformation parameters did not differ significantly from those of healthy controls, whereas load-sensitive regional differences in interventricular septal and RV deformation identified as nominal associations, though not all retained significance after correction for multiple testing, became apparent after birth. These findings suggest that postnatal changes in loading conditions may reveal regional mechanical differences that are not evident during fetal life.