Clinical Significance of Aortic Root Modification Associated With Bicuspid Aortic Valve in Marfan Syndrome
An Observational Cohort Study
Circulation: Cardiovascular Imaging. 2019;12:e008129
Marfan syndrome (MFS), due to a pathogenic mutation in FBN1, is characterized by the development of progressive aortic root dilatation, leading to aortic dissection. It has been demonstrated that,when the aortic diameter reaches 5 cm, the surgical replacement of aortic root may reduce the risk of aortic dissection. The use of a lower aortic root diameter threshold (lower than 5 cm) for surgical replacement may be related to the presence of other conditions, such as a family history of aortic dissection, a diffuse ascending aortic dilatation, vertebral artery tortuosity, and rapid aortic growth. Aortic wall defects may be also associated to the presence of a bicuspid valve, favouring aortic coartation but also aortic aneurysms and aortic dissection. Patients with bicuspid valve have larger aortic root and ascending aorta diameters.
In the French excellence center for Marfan syndrome diagnosis and treatment in Paris, a large group of patients undergoing initial evaluation are regularly followed. In this paper authors aimed to assess, in patients with an FBN1 gene mutation , a peculiar aspect, i.e. whether the presence of a bicuspid aortic valve may be associated to an increase of aortic diameters , changes in aortic shape , and to the occurrence of aortic events.
Authors have examined 1437 patients with an FBN1 gene mutation, and at each visit in all patients the aortic root diameters were measured, and the aortic valve structure and function were assessed by echocardiography. Out of 1342 evaluable patients with FBN1 mutation, 26 patients (1.8%) had a bicuspid aortic valve. In this group of patients the aortic root maximal diameter and the normalized Z score were larger at all ages when compared with patients with normal tricuspid aortic valve; no difference in aortic growth rates was demonstrated.
During follow-up 10 out of 26 patients with bicuspid aortic valve underwent prophylactic root replacementat at a younger age (about 8 years earlier) as compared to those with a tricuspid valve, despite aortic diameter threshlod was similar.
No aortic dissection was reported in Marfan syndrome patients with BAV.
Authors conclude that in patients with a FBN1 mutation, BAV is associated with larger aortic root diameter and normalized Z score. Aortic dissection was not observed. The decision to perform a prophylactic aortic root surgery was taken at younger ages, for similar diameter threshold. Authors underline the lack of evidence, from these results, for lowering aortic diameter thresholds in order to perform preventive aortic root surgery in the presence of BAV in patients with FBN1 mutations.