Z-score -3.46 → normal (small aortic root for BSA). Not Marfan-related aortic dilatation. Revised example (pathologic): Same patient, observed root = 46 mm
[ Z = \frac38 - 52.154.09 = \frac-14.154.09 = -3.46 ] marfan z score
[ Z = \frac46 - 52.154.09 = \frac-6.154.09 = -1.50 \ (\textstill normal) ] Z-score -3
[ Z = \frac\textObserved aortic root diameter - \textPredicted mean diameter\textStandard deviation (SD) of predicted mean ] A Z-score quantifies how many standard deviations a
In the (and 2014 update), the Z-score of the aortic root diameter became a central diagnostic criterion. A Z-score quantifies how many standard deviations a patient’s aortic root measurement deviates from the predicted mean for a healthy individual of the same body surface area (BSA) and age . Key clinical point: An aortic root Z-score ≥ 2.0 is considered abnormally dilated. A Z-score ≥ 3.0 is highly specific for syndromic aortic root pathology. 2. Definition & Mathematical Formula The Z-score is calculated as: