Normal tricuspid septal leaflet offsetting in healthy children: rethinking echocardiographic thresholds for Ebstein's anomaly
S Classen, S Dannesbo, V M Hansson, A Axelsson Raja, R Ottilia B Voegg, A H Christensen, H A Boyd, L R Freud, V Hjortdal, K Iversen, H Bundgaard, N Vejlstrup, A S SillesenAbstract
Background
Ebstein’s anomaly (EA) is a rare congenital malformation of the tricuspid valve, affecting 2-6 per 100,000 live births. Transthoracic echocardiography (TTE) is the diagnostic standard. A universally applied key criterion for EA is apical displacement of the septal tricuspid leaflet >8 mm/m2 body surface area (BSA) in the apical four-chamber view, originating from a study performed in 1984 on a small, predominantly adult cohort. However, diagnosis is now most commonly established during infancy, with a median age at diagnosis of 0.4 years; therefore, BSA-indexed thresholds derived from predominantly adult cohorts may not be appropriate for neonates and pre-school children.
Purpose
To evaluate the clinical utility of the 8 mm/m² TTE threshold in healthy newborns and pre-school children.
Methods
From a prospective, population-based cohort of >25,000 children with newborn cardiac examinations, we randomly sampled 1,000 children with a normal TTE both in the newborn period and at 4-5 years of age. Septal tricuspid offsetting (perpendicular distance from the mitral valve hinge points to the septal tricuspid leaflet hinge point) was measured and indexed by BSA. Distributions were summarised graphically and stratified by sex and age at TTE. We report the proportion of children with offsetting exceeding 8 mm/m2 and compare group means using Welch´s t-test.
Results
Of the 1,000 participants, 50.9 % were girls. Median age at newborn TTE was 12 days (interquartile range [IQR] 8-15 days) and 5.2 (IQR 4.8-5.5) years at follow-up. Mean BSA-indexed offsetting was 11.1 mm/m2 (standard deviation [SD] 3.4; 95% confidence interval [CI] 10.8-11.3; range 0.7-25.1) in newborns and 5.0 mm/m2 (SD 1.6; 95% CI 4.9-5.1; range 0.8-10.7) at follow-up. Among newborns, 82.4% (95% CI 79.9-84.7%) exceeded the historical TTE threshold of 8 mm/m2, while 3.8% (95% CI 2.7-5.2%) did so at follow-up. No differences were observed by sex.
Conclusion
The historical 8 mm/m² criterion is not appropriate for diagnosing EA in newborns and preschool-aged children, as it potentially labels more than 82% of healthy newborns and 3.8% of healthy preschool children as having EA. These findings highlight the need for age-appropriate reference standards for septal tricuspid offsetting.Newborn offsetting distributionFollow-up offsetting distribution