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:
1. Overview & Clinical Context Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder caused by a mutation in the FBN1 gene, leading to fibrillin-1 deficiency. Cardinal manifestations include skeletal, ocular, and cardiovascular abnormalities. The most life-threatening feature is progressive aortic root dilatation , which predisposes to aortic dissection and rupture. marfan z score
Z-score -3.46 → normal (small aortic root for BSA). Not Marfan-related aortic dilatation. Revised example (pathologic): Same patient, observed root = 46 mm In the (and 2014 update), the Z-score of