In type B aortic dissection, when is thoracic endovascular aortic repair (TEVAR) indicated versus medical management?

TEVAR for Type B Aortic Dissection

Immediate Management for All Type B Dissections

Medical therapy with pain relief and blood pressure control is mandatory for all patients with type B aortic dissection, regardless of whether they ultimately receive TEVAR. 1

• Target systolic blood pressure <120 mmHg and heart rate <60 bpm to reduce aortic wall stress 2
• Beta-blockers are first-line antihypertensive agents (esmolol, metoprolol, or labetalol) 1, 2
• Admit to intensive care unit with continuous three-lead ECG monitoring and arterial line 1
• Adequate pain control is essential to achieve hemodynamic targets 1

Decision Algorithm: TEVAR vs Medical Management

Emergency TEVAR (Immediate Intervention Required)

TEVAR is the first-line therapy for complicated acute type B aortic dissection and must be performed emergently. 1

Complicated dissection is defined by any of the following 1:

• Malperfusion (visceral, renal, lower extremity)
• Signs of rupture (hemothorax, increasing periaortic/mediastinal hematoma)
• Persistent or recurrent pain despite full medical therapy
• Uncontrolled hypertension despite maximal medication
• Early aortic expansion on serial imaging

The 30-day mortality for TEVAR in complicated acute type B dissection is 8%, with stroke rate of 8% and spinal cord ischemia of 2% 1

Subacute TEVAR (14-90 Days After Onset)

For uncomplicated acute type B dissection with high-risk anatomical features, TEVAR should be considered in the subacute phase (14-90 days) to prevent late aortic complications. 1, 2

High-risk features include 1:

• Primary entry tear >10 mm
• Initial aortic diameter >40 mm
• Initial false lumen diameter >20 mm
• Partial false lumen thrombosis
• Entry tear located at inner aortic curvature
• Multiple or large fenestrations between true and false lumens

Critical timing consideration: TEVAR performed within 3 days of symptom onset is associated with 2.4-fold increased short-term complications and 2.31-fold increased intermediate-term complications compared to delayed repair. 3 When possible, delay TEVAR by at least 3 days even in complicated cases to reduce morbidity and mortality 3

The INSTEAD-XL trial demonstrated that at 5 years, TEVAR reduced aorta-related mortality (6.9% vs 19.3%, P=0.04) and disease progression (27.0% vs 46.1%, P=0.04) compared to medical therapy alone, though total mortality was not different 1

Medical Management Alone (No TEVAR)

For uncomplicated acute type B dissection without high-risk features, continue medical therapy with close surveillance. 1, 2

• Follow-up imaging at 1,3,6, and 12 months after onset, then yearly if stable 1, 2
• Use CT or MRI for surveillance (MRI preferred to reduce radiation exposure) 1
• Monitor for false lumen expansion, aneurysm formation, new tears, or malperfusion 2

Chronic Type B Dissection (>90 Days)

Intervention is recommended when descending thoracic aortic diameter reaches ≥60 mm in patients at reasonable surgical risk. 1, 2

• Consider intervention at ≥55 mm in low procedural risk patients 1, 2
• Emergency intervention is required for acute symptoms of malperfusion, rupture, or disease progression 1
• Lifelong antihypertensive therapy is mandatory for all chronic dissection patients 1, 2

Common Pitfalls and Caveats

Avoid performing TEVAR in the hyperacute phase (<3 days) unless absolutely necessary for life-threatening complications, as this timing is associated with significantly increased morbidity including branch vessel complications, renal complications, and need for reinterventions 3

Open surgery is indicated instead of TEVAR when 1:

• Severe lower extremity arterial disease prevents endovascular access
• Severe tortuosity of iliac arteries
• Sharp angulation of aortic arch
• Absence of adequate proximal landing zone for stent graft

Post-TEVAR surveillance is critical: imaging at 1,6, and 12 months post-operatively, then yearly until the fifth post-operative year 1 Endoleaks occur in up to 20% of patients and are the most important risk factor for post-TEVAR rupture 4

TEVAR protects only the covered thoracic segment—the abdominal aorta remains at risk and requires continued surveillance, as false lumen area does not change significantly in the abdominal segment despite thoracic TEVAR 5

Approximately 35% of TEVAR patients experience at least one aorta-specific complication post-operatively, with roughly half requiring re-intervention 4