What are the key factors in risk stratification for a patient with a tubercular mycotic aneurysm of the thoracic aorta (TAA) undergoing open TAA repair, considering their age, overall health, comorbidities such as coronary artery disease (CAD), chronic obstructive pulmonary disease (COPD), and peripheral arterial disease (PAD)?

Risk Stratification for Open TAA Repair

For patients with tuberculous mycotic aneurysm of the thoracic aorta requiring open repair, the key risk factors that substantially increase operative mortality are advanced age (≥75 years), preoperative renal dysfunction (stage 3 or greater CKD), COPD with FEV1 ≤50% predicted, and left ventricular dysfunction, though experienced multidisciplinary aortic teams can achieve excellent outcomes despite these comorbidities. 1

Primary Risk Factors for Operative Mortality

The following patient characteristics are independently associated with increased perioperative morbidity and mortality after open TAA repair:

Age-Related Risk

• Age 65-74 years: Odds ratio 1.8 (95% CI, 1.4–2.4; P <0.001) 1
• Age ≥75 years: Odds ratio 2.6 (95% CI, 2.0–3.5; P <0.001) 1
• However, carefully selected octogenarians can achieve similar operative mortality rates as younger patients (5.2% vs 5.7%; P=0.852) when treated by experienced surgeons in multidisciplinary aortic teams 1

Cardiac Risk Factors

• Left ventricular dysfunction: Post-operative mortality risk increases with reduced ejection fraction 1
• Coronary artery disease (CAD): Increases cardiac event risk perioperatively 1
• Notably, patients with LVEF <40% were not more prone to operative death (OR, 0.28; 95% CI, 0.02–4.14; P=0.58) or long-term death (OR, 0.55; 95% CI, 0.17–1.80; P=0.23) when treated in specialized centers 1

Pulmonary Risk Factors

• COPD with FEV1 ≤50% predicted: Substantially increases operative risk 1
• Pulmonary disease: Predictive of poor outcomes after both open and endovascular repair 1

Renal Risk Factors

• Preoperative renal insufficiency (stage 3 or greater CKD) or hemodialysis dependence: Major risk factor for perioperative mortality 1
• Renal dysfunction: Increases post-operative mortality risk 1

Vascular Risk Factors

• Previous stroke: Associated with increased perioperative morbidity 1
• Peripheral arterial disease (PAD): Contributes to overall surgical risk profile 1

Special Considerations for Mycotic Aneurysms

Mycotic aneurysms, including tuberculous aneurysms, warrant intervention at smaller diameters regardless of standard size thresholds due to increased rupture risk. 1

Mycotic Aneurysm-Specific Factors

• Intervention is justified at diameters <5.5 cm for mycotic aneurysms 1
• Symptoms consistent with enlarging aneurysm portend potential rupture and suggest need for surgery regardless of absolute diameter 1
• Rapid aneurysm growth (≥0.5 cm/year) suggests need for intervention regardless of diameter 1

Treatment Approach for Tuberculous Aneurysms

• Open repair remains the definitive treatment for mycotic aneurysms, particularly tuberculous aneurysms, when combined with appropriate anti-tuberculosis therapy 2
• TEVAR with anti-TB medications may be reasonable initial treatment in high-risk patients, but careful long-term follow-up is mandatory due to risk of recurrent infection 2
• Critical pitfall: One case report documented fatal aortic rupture 4 months after discontinuing anti-TB therapy following endovascular repair, highlighting the risk of infection recurrence with endovascular approaches 3

Risk Stratification Algorithm

Step 1: Assess Absolute Contraindications to Open Repair

• Hemodynamic instability in ruptured aneurysm (consider endovascular if stable) 1
• Life expectancy <2 years 1

Step 2: Count Major Risk Factors

Assign one point for each:

• Age ≥75 years 1
• COPD with FEV1 ≤50% 1
• Stage 3+ CKD or dialysis dependence 1
• LVEF <40% 1
• Previous stroke 1

Step 3: Determine Risk Category and Management

Low Risk (0-1 risk factors):

• Open repair is reasonable at standard thresholds (≥6.0 cm for TAAA, ≥5.5 cm for descending TAA) 1
• For mycotic aneurysms: proceed with open repair regardless of size 1
• Expected operative mortality: 5-8% in experienced centers 1

Moderate Risk (2-3 risk factors):

• Refer to multidisciplinary aortic team for comprehensive evaluation 1
• Open repair remains feasible with meticulous perioperative preparation 1
• Consider endovascular repair if suitable anatomy exists 1
• For mycotic aneurysms: multidisciplinary team decision weighing infection control vs operative risk 2

High Risk (≥4 risk factors):

• Consider continued observation if diameter <6.0 cm and asymptomatic 1
• Endovascular repair preferred if suitable anatomy 1
• For mycotic aneurysms in high-risk patients: TEVAR with prolonged anti-TB therapy may be reasonable, but requires intensive surveillance for recurrent infection 2, 3
• If anatomy unsuitable for endovascular repair and life expectancy >2 years: refer to high-volume multidisciplinary aortic team 1

Critical Pitfalls to Avoid

Pitfall 1: Applying Standard Size Thresholds to Mycotic Aneurysms

• Do not wait for standard 5.5-6.0 cm thresholds in mycotic aneurysms 1
• Intervene at smaller diameters due to increased rupture risk 1

Pitfall 2: Dismissing Surgery Based on Comorbidities Alone

• Multiple comorbidities do not automatically preclude open repair 1
• Multidisciplinary aortic teams achieve excellent outcomes despite comorbid conditions through meticulous perioperative care 1

Pitfall 3: Premature Discontinuation of Anti-TB Therapy After Endovascular Repair

• Fatal rupture can occur months after stopping anti-TB therapy 3
• If endovascular approach used for tuberculous aneurysm, maintain prolonged anti-TB therapy and intensive surveillance 2, 3

Pitfall 4: Underestimating Volume-Outcome Relationship

• Open TAA repair outcomes are highly dependent on center volume 1
• Mortality can reach 20% in low-volume centers vs 5-8% in high-volume centers 1, 4
• Always refer complex cases to high-volume centers with multidisciplinary aortic teams 1

Pitfall 5: Ignoring Life Expectancy in Decision-Making

• Open repair is reasonable only if life expectancy exceeds 2 years 1
• In patients with limited life expectancy, continued observation may be appropriate even for larger aneurysms 1