Abstract Body (Do not enter title and authors here): Background:
Renal artery stenosis (RAS) is common in Williams syndrome (WS). Gold standard advanced cardiovascular (CV) imaging (aCVI) required to confirm RAS (CT, catheter angiography, or MRI) often requires anesthesia, which is associated with sudden CV events in WS. We sought to identify echocardiographic CV measures associated with abdominal arteriopathy in WS that might be used to determine which patients require aCVI.

Methods:
We retrospectively reviewed all patients with WS treated at our center with aCVI from 2015 to 2022. From aCVI obtained, we measured the diameter of the abdominal aorta (Ao) at the hiatus (AoH), right renal artery (AoRRA), and celiac trunk (AoCA), and the origin, proximal aspect (4mm from the origin), and midpoint of the RRA, left renal artery (LLA), celiac artery (CA), superior mesenteric (SMA) and inferior mesenteric (IMA) arteries. For all aortic measurements, we calculated Z-scores using published formulae (Hegde, 2015). To our knowledge, there are no Z-scores available for pediatric SMA, IMA, or renal arteries, so we used a ratio reflecting the most severe area of narrowing (either origin:midpoint or proximal:midpoint). From the echo closest in absolute time to aCVI, we measured the ascending Ao wall thickness in the suprasternal sagittal echocardiographic view and compared it to the same measurement in age- and height-matched controls.

Results:
There were 48 patients with WS and aCVI included in the study (26 CT, 17 cath, 5 MRI). In 44 (92%), the abdominal Ao was diffusely stenotic (Z-scores <-2 at AoH, AoCA, or AoRRA). There was strong correlation between AoH and AoCA (r²=0.76), AoH and AoRRA (r²=0.79), and AoCA and AoRRA (r²=0.69) (all Z-score comparisons). There was moderate correlation between AoH Z-score and worst narrowing ratio of CA (r²=0.40), and between the worst narrowing ratios of the RRA and LRA (r²=0.53). Ascending Ao from 47 patients with WS (obtained at a median 44 days from aCVI) was thicker in WS compared to 47 controls (22 vs 17mm, p<0.001), but did not correlate with any abdominal arterial measures.

Conclusion:
Though often a marker of severe cardiac disease in WS, ascending Ao thickness does not predict abdominal arterial stenoses in WS. However, stenosis of AoH on aCVI is correlated with other abdominal stenoses in WS. Since AoH can be measured by echo, more work is necessary to determine whether this could serve in WS as an indicator of further abdominal stenoses and need for subsequent aCVI.