What is the recommended risk scoring system for a patient with a tubercular (TB) mycotic aneurysm of the thoracic aorta undergoing Thoracic Endovascular Aortic Repair (TEVAR)?

Risk Scoring for TEVAR in TB Mycotic Aneurysm

There is no validated risk scoring system specifically for TB mycotic aneurysms undergoing TEVAR; however, specific risk factors that predict poor outcomes have been clearly identified and should guide decision-making.

Key Risk Factors Predicting Poor Outcome

The following factors are associated with treatment failure and increased mortality when performing TEVAR for TB mycotic aneurysm:

High-Risk Features (Contraindications or Relative Contraindications)

• Persistent signs of sepsis preoperatively despite ≥1 week of appropriate antimicrobial therapy is the strongest predictor of poor outcome and should prompt reconsideration of TEVAR 1, 2
• Presence of aortoenteric or aortobronchial fistula is associated with mortality ranging from 40-60% and infection recurrence of 33-60% 1, 2, 3
• Large undrained periaortic abscess is a contraindication for TEVAR and requires drainage before intervention 1, 2
• Rupture or impending rupture significantly worsens prognosis, though TEVAR may serve as a life-saving bridge procedure 1, 4

Patient-Specific Risk Factors for General TEVAR Mortality

While not specific to mycotic aneurysms, the following factors predict 1-year mortality after TEVAR and should be considered:

• Age >70 years (hazard ratio 5.8) 5
• Need for adjunctive intraoperative procedures (e.g., brachiocephalic or visceral stents, arch debranching; hazard ratio 4.5) 5
• Peripheral arterial disease (hazard ratio 3.0) 5
• Coronary artery disease (hazard ratio 2.4) 5
• Chronic obstructive pulmonary disease (hazard ratio 1.9) 5

Risk Stratification Algorithm

Use this approach to stratify risk:

1. First, assess for absolute contraindications:

   • Active sepsis persisting after 1 week of appropriate antibiotics 2
   • Aortobronchial or aortoenteric fistula (consider open repair or hybrid approach) 1, 2
   • Large undrained periaortic abscess 2

2. Second, count the number of patient-specific risk factors (age >70, CAD, COPD, PAD, need for complex procedure):

   • 1 risk factor: 1-3% predicted 1-year mortality 5
   • 2 risk factors: 10% predicted 1-year mortality 5
   • 3 risk factors: 27% predicted 1-year mortality 5
   • ≥4 risk factors: 54% predicted 1-year mortality 5

3. Third, evaluate infection-specific factors:

   • Positive blood cultures with persistent bacteremia despite antibiotics 1, 4
   • Extent of periaortic inflammation on imaging 1

Essential Pre-TEVAR Requirements

To optimize outcomes, the following must be achieved before TEVAR:

• Minimum 1 week of pre-operative antibiotic therapy to improve outcomes 1, 2
• Image-guided drainage of any periaortic fluid collections before device placement 1
• Resolution or significant improvement of sepsis before proceeding 1, 2
• Four-drug anti-tuberculosis therapy initiated and continued throughout treatment 6, 7

Outcomes Data for TB Mycotic Aneurysm

The available evidence shows:

• In-hospital/30-day mortality: 0-7% for TEVAR vs. 7% for open surgery 6
• Overall mortality: 5% for TEVAR vs. 10% for open surgery 6
• Infection-related complications: 17% in mycotic thoracic aneurysms, with 67% being fatal 4
• Critical timing: 80% of infection-related complications occur within the first year 4

Critical Management Pitfalls to Avoid

The most important caveat is that TEVAR places a foreign body in an infected field without debridement, which fundamentally differs from open surgical principles 1, 2. However, this concern has not translated into worse outcomes compared to open surgery in reported series 2.

Fatal recurrence can occur months to years after apparent cure: One case report documented fatal aortic rupture 4 months after discontinuing anti-TB therapy at 16 months, despite initial clinical and radiological resolution 7. This underscores the need for:

• Lifelong suppressive antimicrobial therapy when endovascular devices are retained 1, 2
• Rigorous long-term surveillance with contrast-enhanced CT to detect perigraft fluid, gas bubbles, or aneurysm sac enlargement (>2% increase) 2

Comparison to General TEVAR Risk Scoring

The 2024 ESC Guidelines describe the DISSECT system (Duration, Intimal tear location, Size, Segmental extent, Clinical complications, Thrombosis) for aortic dissection 1, but this is not applicable to mycotic aneurysms. No equivalent validated scoring system exists for infectious aortopathy.