What is the treatment for a mural thrombus in the descending thoracic aorta?

Treatment of Mural Thrombus in the Descending Thoracic Aorta

Initiate immediate therapeutic anticoagulation with unfractionated heparin or low molecular weight heparin as first-line therapy, targeting INR 2.0-3.0 when transitioning to warfarin, and continue for a minimum of 6 months with imaging-confirmed thrombus resolution. 1, 2

Initial Diagnostic Confirmation

• Confirm thrombus characteristics using contrast-enhanced CT angiography or MRI to assess size, mobility, adherence to the aortic wall, and location 1, 2
• Identify high-risk features including mobile thrombus, poor wall adherence, or location in high-flow areas that substantially increase embolic risk 1
• Exclude cardiac sources with transthoracic echocardiography and Holter monitoring to rule out concurrent cardiac thrombus 1, 2
• Screen for underlying prothrombotic disorders (present in approximately 38% of cases) and concurrent malignancy (present in approximately 38% of cases) 3

Primary Treatment Algorithm

First-Line: Anticoagulation Therapy

Immediate anticoagulation is the standard of care - delaying treatment significantly increases risk of embolic stroke and limb loss 1, 2, 4

• Start unfractionated heparin or low molecular weight heparin as bridge therapy while initiating warfarin 1, 2
• Target INR 2.0-3.0 for warfarin therapy 1, 5
• Monitor INR weekly during initiation and monthly once stable, maintaining time in therapeutic range >70% 1, 2
• Continue anticoagulation for minimum 6 months, with duration guided by repeated imaging to confirm thrombus resolution 1, 2

Indications for Endovascular Intervention (TEVAR)

Consider thoracic endovascular aortic repair (TEVAR) as first-line therapy in the following scenarios:

• Mobile or pedunculated thrombus with high embolic potential 1, 3, 6
• Recurrent embolism despite therapeutic anticoagulation 3, 4, 6
• Contraindication to anticoagulation (active bleeding, recent surgery, high fall risk) 3, 6
• Persistent thrombus after 3-6 months of anticoagulation 7, 6
• Large thrombus burden (>10mm thickness) in suitable anatomy 7

TEVAR demonstrates superior outcomes with 93.1% complete thrombus exclusion and minimal recurrence rates compared to medical management alone (which has 34.6% persistent thrombus and 25-50% embolic recurrence) 7, 6

Indications for Open Surgical Thrombectomy

Reserve open surgery for specific anatomical or technical limitations:

• Severe tortuosity of iliac arteries precluding endovascular access 8
• Sharp angulation of aortic arch preventing stent-graft deployment 8
• Absence of adequate proximal landing zone for endovascular repair 8
• Failed endovascular therapy with persistent mobile thrombus 2, 3

Perform in hybrid operating room with completion angiography capability to detect residual thrombus 2

Surveillance Imaging Protocol

• Perform serial CT angiography at 2 weeks, 1 month, 3 months, and 6 months to assess thrombus resolution 1
• Do not discontinue anticoagulation based solely on symptom improvement without imaging confirmation of complete thrombus resolution 1, 2
• Extend anticoagulation indefinitely if persistent aortic wall abnormalities remain or if underlying hypercoagulable state cannot be corrected 1, 2

Management of Embolic Complications

If acute limb ischemia or visceral embolization occurs:

• Assess limb viability immediately using Doppler signals 1, 2
• Perform urgent revascularization (thrombectomy or bypass) for salvageable limbs 1, 2
• Follow with definitive treatment of aortic source (typically TEVAR) to prevent recurrent embolization 1, 2
• Continue therapeutic anticoagulation throughout to prevent thrombus propagation 1, 2

Critical Pitfalls to Avoid

• Do not confuse mural thrombus with intramural hematoma (IMH) - IMH represents hemorrhage within the aortic wall rather than luminal thrombus and follows different management algorithms per ESC guidelines 1, 8
• Do not delay anticoagulation once diagnosis is confirmed - this is the single most important intervention to prevent catastrophic embolic events 1, 2
• Do not stop anticoagulation prematurely - approximately 35% of patients have persistent thrombus requiring extended therapy 4, 6
• Do not assume cardiac source - in 82.4% of cases, descending thoracic aortic mural thrombus is the primary embolic source 7

Treatment Outcomes by Modality

Recent literature demonstrates evolving treatment paradigm:

• Medical management alone: 34.6% persistent thrombus, 25-50% embolic recurrence, 31% require secondary surgery 7, 4, 6
• TEVAR: 93.1% complete exclusion, minimal recurrence, increasingly preferred first-line option for suitable anatomy 7, 6
• Open surgery: 31.6% persistent thrombus, higher mortality but definitive when endovascular not feasible 7