Do patients with Turner syndrome develop thoracic aortic aneurysm?

Do Turner Syndrome Patients Develop Thoracic Aortic Aneurysms?

Yes, patients with Turner syndrome are at significantly increased risk for developing thoracic aortic aneurysms (TAA), particularly of the ascending aorta and aortic root, with approximately 33% demonstrating aortic dilation and a substantially elevated risk of aortic dissection compared to the general population. 1

Prevalence and Risk Magnitude

• Approximately 33% of women with Turner syndrome have aortic dilation when defined as an ascending-to-descending aortic diameter ratio greater than 1.5 1
• The population-based incidence of aortic dissection is 36 per 100,000 Turner syndrome patient-years (1.4% lifetime risk) compared to only 6 per 100,000 in the general Danish population, representing a 6-fold increased risk 1
• Between 50% of patients have cardiovascular defects including ascending aortic dilation (33%), bicuspid aortic valve (15-30%), and aortic coarctation (7-18%) 2

Mechanism and Associated Risk Factors

The development of TAA in Turner syndrome is multifactorial and strongly associated with:

• Bicuspid aortic valve (BAV): Present in 10-25% of patients and independently associated with larger ascending aortic diameters 1, 2
• Aortic coarctation: Present in approximately 8% of patients 2
• Hypertension: A major modifiable risk factor for aortic dissection 1
• Underlying aortopathy: Intrinsic weakness of the aortic wall independent of other structural abnormalities 3

Research demonstrates a spectrum of aortic valve abnormalities with increasing severity of valve fusion correlating with larger ascending aortic diameters: tricuspid valves (16.9±3.3 mm/m²), partially fused valves (18.3±3.3 mm/m²), and bicuspid/unicuspid valves (19.8±3.9 mm/m²) 4

Critical Measurement Considerations

Body size indexing is mandatory because absolute aortic measurements severely underestimate dissection risk in these characteristically short-statured patients:

• For patients ≥15 years old: Calculate the Aortic Size Index (ASI) by dividing maximal aortic diameter (cm) by body surface area (m²) 1
• ASI >2.0 cm/m² is abnormal 1
• ASI ≥2.5 cm/m² is associated with significantly increased dissection risk 1
• For patients <15 years old: Use Turner syndrome-specific z-scores rather than general population references, as general z-scores are significantly higher and lead to overestimation of risk 1, 5

Surveillance Algorithm

All patients with Turner syndrome require lifelong aortic surveillance regardless of initial findings 1:

Low-Risk Patients (No BAV, coarctation, hypertension, or dilation):

• Children: Re-evaluation every 5 years 1
• Adults: Surveillance imaging with TTE or MRI every 10 years 1

Moderate-Risk Patients (ASI ≤2.3 cm/m² with stable measurements, age ≥15):

• Surveillance imaging every 2-3 years 1, 6

High-Risk Patients (ASI >2.3 cm/m²):

• At least annual surveillance imaging 1, 6
• More frequent imaging as ASI approaches 2.5 cm/m² 1

Additional Surveillance Triggers:

• Before planned pregnancy (mandatory cardiovascular evaluation) 1, 6
• Presence of BAV, coarctation, or hypertension warrants more frequent monitoring 1

Surgical Intervention Thresholds

For patients ≥15 years old with ASI ≥2.5 cm/m² plus additional risk factors (BAV, coarctation, hypertension), prophylactic surgical replacement of the aortic root/ascending aorta is reasonable 6, 7

For short-statured but obese patients or those with low body weight relative to height, an absolute aortic diameter >4.0 cm may be more accurate than ASI alone for determining dissection risk 1

Clinical Outcomes and Mortality

• The average age of aortic dissection in Turner syndrome is 31 years 1
• Less than half of patients survive an aortic dissection event 1
• Aortic dissection represents a major cause of increased cardiovascular mortality in Turner syndrome, occurring at younger ages than the general population 7
• The majority of dissections occur in patients with known risk factors, though dissection can occur even in the absence of traditional risk factors 1, 3

Critical Pitfalls to Avoid

• Never use absolute aortic measurements without body size indexing in Turner syndrome patients, as this critically underestimates dissection risk 7, 5
• Do not assume normal cardiovascular anatomy based on physical examination alone, as up to 50% have cardiovascular defects requiring imaging to detect 7
• Do not use general population z-scores in patients <15 years old, as these significantly overestimate risk and may lead to inappropriate activity restrictions or unnecessary interventions 5
• Baseline cardiac MRI at diagnosis should not be omitted, as echocardiography alone misses important structural abnormalities 7