Thoracic aneurysm is a silent disease with a potential mid-term high risk of death or major complications. Few data are available on the real incidence of major complications in case of small and moderate thoracic aneurysm. Different factors are supposed to increase the risk of aortic enlargement as high blood pressure and sleep disorder breathing. The modality of imaging and clinical follow-up are well defined. In this prospective observational study, the aim to assess the incidence of of major complications during follow-up in a population of patients with a small or moderate thoracic aneurysm. The study will also try to identify systemic factors influencing aneurysm evolution.

Inclusion Criteria:

• Documentation of an aortic root aneurysm > 40 mm
• Agreement to participate to a longitudinal study and available for a 5 years follow-up

Exclusion Criteria:

• Presence of comorbidities or pathology with a prognosis of less than 1 year
• Personal or family history of genetically documented elastic tissue disease or patient meeting the GAND clinical criteria suggestive of Marfan disease
• High-grade mitra-aortic valve disease, even if asymptomatic
• Unbalanced hypertension ≥ 180/110 mmHg
• Aneurysm (regardless of thoracic or abdominal location) ≥ 50 mm
• Aneurysm (regardless of thoracic or abdominal location) with documented progression of more than 5 mm over one year
• History of aortic surgery or endovascular intervention and history of type B aortic dissection of medical treatment
• Renal insufficiency on dialysis, or GFR< 30 ml/mn (CKD-EPI)

Patients with moderate thoracic aortic aneurysms for primary prevention