Gal DB, Lechich KM, Jensen HK, et al. - STJ:An (sinotubular junction-to-aortic annulus ratio) allows an accurate evaluation of supravalvar aortic stenosis (SVAS) severity in Williams syndrome (WS). STJ:An is not only independent of physiologic state but also has fewer technical limitations in comparison with Doppler echocardiography and catheterization. STJ:An may augment conventional methods in guiding surgical management decisions.

• All preintervention echocardiograms (n=168) in patients with WS with SVAS (n=54 children; median age at scan 1.2 years) were reviewed to investigate if SVAS severity could be determined by STJ:An.

• STJ:An was calculated and 2 mean gradient prediction models were developed (Model 1 used the simplified Bernoulli's equation, and model 2 used computational fluid dynamics (CFD).

• Median STJ:An was 0.76 (IQR 0.63 to 0.84).

• It was noted that model 1 underpredicted clinical gradients, whereas model 2 showed good correlation with STJ:An through all severity ranges and showed increased pressure recovery distance with reduced STJ:An.

• In a given patient, the median potential variability in catheterization-derived gradients was reported to be 14.5 mm Hg (IQR 7.5 to 19.3).

• Through all SVAS severity levels, clinical data are well-predicted by CFD.