Aortic Root Dilation Cut-off According to the European Society of Cardiology (ESC)
According to the 2024 ESC guidelines, aortic root dilatation is defined as an aortic diameter >40 mm in males and >36 mm in females, or an indexed diameter/BSA (aortic size index [ASI]) >22 mm/m² 1.
Definition and Diagnostic Criteria
The ESC provides clear parameters for identifying aortic root dilatation:
Technical definition: Aortic dilatation is defined as an aortic diameter >2 standard deviations of the predicted mean diameter depending on age, sex, and body size (z-score >2) 1
Clinical practice thresholds:
- Males: >40 mm
- Females: >36 mm
- Indexed diameter/BSA: >22 mm/m²
For patients with extreme body surface area (BSA) or age values, the use of z-scores is recommended for more accurate assessment 1
Measurement Techniques
Proper measurement technique is crucial for accurate assessment:
- Measurements should be made from the parasternal long-axis view using the leading edge-to-leading edge convention 1
- 2D measurements are preferred over M-mode measurements 1
- Comprehensive assessment should include measurements at:
- Aortic valve annulus (hinge point of aortic leaflets)
- Sinuses of Valsalva
- Sinotubular junction
- Proximal ascending aorta 1
Normal Reference Values
The 2018 European Association of Cardiovascular Imaging provides these normal reference values for aortic root dimensions 1:
| Aortic root segment | Men (cm) | Women (cm) | Men (cm/m²) | Women (cm/m²) |
|---|---|---|---|---|
| Annulus | 2.6 ± 0.3 | 2.3 ± 0.2 | 1.3 ± 0.1 | 1.3 ± 0.1 |
| Sinuses of Valsalva | 3.4 ± 0.3 | 3.0 ± 0.3 | 1.7 ± 0.2 | 1.8 ± 0.2 |
| Sinotubular junction | 2.9 ± 0.3 | 2.6 ± 0.3 | 1.5 ± 0.2 | 1.5 ± 0.2 |
| Proximal ascending | 3.0 ± 0.4 | 2.7 ± 0.4 | 1.5 ± 0.2 | 1.6 ± 0.3 |
Risk Stratification and Follow-up
The ESC guidelines recommend different approaches based on risk factors:
- Both aortic size index (ASI) and aortic height index (AHI) improve risk stratification for adverse aortic events 1
- BSA correction may underestimate risk in overweight patients, so height-based correction (AHI) is becoming more popular 1
Surveillance Recommendations:
For patients with non-heritable thoracic aortic disease:
- Baseline CCT/CMR and reimaging by TTE in one year for aortic diameters 40-44 mm
- For diameters 45-49 mm, confirmation by CCT or CMR is recommended 1
- More frequent monitoring if growth rate ≥3 mm/year
Special Considerations for Specific Conditions
Bicuspid Aortic Valve
- Complete imaging of the thoracic aorta is necessary at diagnosis 2
- Annual monitoring of the aortic root/ascending aorta with TTE is recommended 2
- Additional imaging with CMR/CCT every 3-5 years 2
- Prophylactic aortic surgery should be considered when aortic diameter reaches ≥45 mm, or lower with additional risk factors 2
Marfan Syndrome
The ESC provides specific surgical thresholds for Marfan syndrome 1:
- Surgery is recommended when aortic root maximal diameter is >50 mm
- Surgery is also recommended at 46-50 mm with:
- Family history of dissection
- Progressive dilation >2 mm/year
- Severe aortic or mitral regurgitation
- Desire for pregnancy
Common Pitfalls to Avoid
- Failing to index measurements to body size, especially in patients with extreme BSA values
- Not using z-scores when appropriate for extreme BSA or age values
- Overlooking the need for comprehensive assessment of all aortic segments
- Inadequate follow-up imaging based on initial measurements
- Not recognizing associated conditions like bicuspid aortic valve that may influence management decisions
By following these ESC guidelines for aortic root dilation cut-offs, clinicians can accurately identify patients at risk and implement appropriate monitoring and intervention strategies to prevent serious complications.