New equations and a critical appraisal of coronary artery Z scores in healthy children.

The aim of this study was to find the best model to obtain valid and normally distributed Z scores for coronary artery (CA) diameters in a large, heterogeneous population of healthy children. Echocardiography was performed on 1,033 healthy children. Several regression models were tested with height, weight, body surface area, and aortic valve diameter. The computed Z scores were tested for normal distribution and stability. CA diameter was best predicted using regression with the square root of body surface area. The weighted least squares method yielded normally distributed and very stable Z-score estimates for all CA segments. In prepubertal children, aortic valve diameter was also a valid predictor of CA diameter. This study shows two valid methods to estimate Z scores for CA size in children of all ages. Such Z scores are important for risk stratification in patients with Kawasaki disease. Copyright © 2011 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.