Takayasu arteritis

Takayasu arteritis (TAK) is a chronic granulomatous large-vessel vasculitis primarily affecting the aorta and its major branches, including the subclavian, carotid, renal, and pulmonary arteries. It predominantly affects young women (typically under 40 years) and is the most common large-vessel vasculitis in individuals under 50 years worldwide. TAK causes arterial stenosis, occlusion, and aneurysm formation, leading to limb ischaemia, hypertension, stroke, and organ failure if untreated. Early diagnosis is challenging as the inflammatory phase may precede vascular changes by months to years.

Australian Context

TAK is rare in Australia with an estimated incidence of 1–2 per million per year. It is more prevalent in individuals of Asian, Middle Eastern, and Indigenous ancestry. In Australia, TAK may present to emergency departments, vascular surgery, nephrology, or general medicine before reaching rheumatology. Awareness across specialties is essential for early diagnosis. The Vasculitis Foundation of Australia supports patients with rare vasculitides including TAK.

Granulomatous Inflammation

TAK is characterised by transmural granulomatous inflammation of the aorta and its major branches. Dendritic cells in the adventitia present antigens to CD4+ and CD8+ T cells, triggering Th1 and Th17 responses with production of IFN-γ, TNF-α, and IL-17. NK cells and γδ T cells also contribute to vascular injury. The resulting panarteritis leads to intimal hyperplasia, fibrosis, luminal stenosis, and occlusion. In contrast to GCA, giant cells are less prominent in TAK.

Vascular Patterns

Six angiographic types are recognised based on the distribution of vessel involvement (Numano classification): Type I (aortic arch branches), Type IIa (ascending aorta and arch), Type IIb (descending thoracic aorta), Type III (abdominal aorta and renal arteries), Type IV (abdominal aorta ± renal), Type V (combined). Renal artery stenosis causing renovascular hypertension is a key complication across several types. Pulmonary artery involvement occurs in up to 50% of cases.

Two Clinical Phases

Phase 1 — Inflammatory (pre-pulseless): Constitutional features dominate — fever, fatigue, weight loss, night sweats, arthralgia, myalgia. Carotidynia (tenderness over carotid arteries) is characteristic. Phase 1 may last months to years before vascular changes become apparent on imaging or examination.

Phase 2 — Occlusive (pulseless): Features of vascular stenosis and ischaemia emerge — pulse asymmetry or absence, blood pressure discrepancy between arms (>10 mmHg), bruits over subclavian/carotid/renal arteries, arm claudication, dizziness, visual disturbance, renovascular hypertension, and angina from coronary ostial stenosis.

Key Examination Findings

• Absent or diminished radial or brachial pulse (earning the name "pulseless disease")
• Blood pressure difference >10 mmHg between arms
• Vascular bruits (subclavian, carotid, aortic, renal)
• Carotidynia on palpation
• Hypertension (often severe, from renal artery stenosis)
• Fundoscopic changes — hypertensive retinopathy, arteriovenous collaterals (Takayasu retinopathy)

• Essential
  ESR and CRP

  Elevated in active inflammatory phase. May normalise even with ongoing vascular progression — imaging is required to assess structural disease activity independently.
• Essential
  Blood Pressure (Both Arms and Legs)

  Bilateral arm and leg blood pressure measurement essential. Discrepancy >10 mmHg between arms is significant. Use ankle-brachial index. Subclavian stenosis may cause falsely low upper limb readings.
• Essential
  CT Angiography (CTA) or MR Angiography (MRA)

  Defines vascular anatomy, stenosis, occlusion, and aneurysm extent. MRA preferred for younger patients (no radiation). CTA faster and more widely available for acute assessment. Both are standard for initial mapping.
• Available
  PET-CT

  FDG-PET detects active aortic and branch vessel inflammation (increased FDG uptake). Most useful for assessing inflammatory activity when inflammatory markers are normal. Not available in all Australian centres.
• Available
  Vascular Ultrasound

  Carotid, subclavian, and renal artery Doppler ultrasound for stenosis assessment. Non-invasive, widely available, no radiation — useful for monitoring known lesions.
• Referral
  Echocardiography

  Assess aortic regurgitation (from aortic root dilation), left ventricular function, and pulmonary hypertension. Important baseline and surveillance tool.

Use the Indian Takayasu Arteritis Activity Score (ITAS2010) or NIH Activity Score to standardise disease activity assessment at each visit.

Corticosteroid Induction

Prednisolone 1 mg/kg/day (max 60–80 mg/day) is the initial treatment for active TAK. Response is monitored by clinical symptoms, inflammatory markers, and serial imaging. Steroid taper begins after achieving remission (typically 4–6 weeks), aiming for prednisolone ≤10 mg/day by 6–12 months. Many patients require prolonged low-dose steroids to maintain remission.

Steroid-Sparing Immunosuppression

Methotrexate (20–25 mg/week) or azathioprine (2 mg/kg/day) are conventional first-line steroid-sparing agents. Mycophenolate mofetil (2–3 g/day) is an alternative. These agents reduce relapse risk and cumulative steroid exposure. They are introduced alongside or shortly after starting corticosteroids. Clinical and imaging response determines continuation.

Biologic Therapy

TNF inhibitors (infliximab 5 mg/kg IV, tocilizumab 8 mg/kg IV monthly) are effective for refractory TAK. Tocilizumab is increasingly favoured given its established role in large-vessel vasculitis. Used when conventional immunosuppression fails to achieve or maintain remission, or in high-relapse-risk patients. Rituximab has limited evidence in TAK.