A 58-year-old man from Delhi presents with a 3-week history of fever, malaise, and progressive dyspnea. On examination, he has a blood pressure of 165/95 mmHg, a new diastolic murmur, and petechial rash on his lower extremities. Laboratory investigations show elevated ESR (78 mm/h), CRP 12 mg/dL, and urinalysis reveals hematuria with RBC casts. Blood cultures are sterile. Coronary angiography shows no atherosclerotic disease but reveals smooth, tapered narrowing of the left anterior descending coronary artery with involvement of the ostium. What is the most likely diagnosis?

Explanation

## Diagnosis: Takayasu Arteritis ### Clinical Presentation Alignment **Key Point:** Takayasu arteritis is a large-vessel vasculitis affecting the aorta and its major branches, with a predilection for young to middle-aged individuals (peak 20–40 years, but can present up to 60 years). The patient's constellation of findings is pathognomonic: - **Systemic inflammation:** fever, malaise, elevated inflammatory markers (ESR, CRP) - **Coronary involvement:** smooth, tapered ostial narrowing of LAD — a hallmark of Takayasu (coronary ostial stenosis occurs in ~10% of cases) - **Aortic branch involvement:** diastolic murmur suggests aortic regurgitation from aortic root dilatation - **Glomerulonephritis:** hematuria with RBC casts from secondary renal artery involvement or immune complex deposition - **Sterile blood cultures:** excludes infective endocarditis ### Pathophysiology ```mermaid flowchart TD A[Takayasu Arteritis]:::outcome --> B[Large-vessel vasculitis] B --> C[Granulomatous inflammation<br/>of media and adventitia] C --> D[Aorta and proximal branches] D --> E[Coronary ostial stenosis] D --> F[Aortic regurgitation] D --> G[Renal artery stenosis<br/>+ secondary HTN] E --> H[Angina, MI, sudden death] F --> H G --> I[Hypertension] ``` ### Diagnostic Criteria (Modified Ishikawa) - **Major:** aortic root dilatation, coronary artery involvement, aortic branch stenosis - **Minor:** elevated ESR, carotid tenderness, aortic regurgitation, pulmonary artery involvement **High-Yield:** Takayasu is the most common cause of secondary hypertension in young Asian women; coronary ostial involvement is specific to Takayasu and distinguishes it from atherosclerotic CAD. ### Imaging Findings - **CT/MRI:** smooth, tapered narrowing ("rat-tail" appearance) of aorta and branches - **Coronary angiography:** ostial stenosis with smooth narrowing (as in this case) - **PET-CT:** increased uptake in aorta and branches during active inflammation **Clinical Pearl:** The diastolic murmur in this patient reflects aortic regurgitation from aortic root involvement — a sign of active or chronic inflammation. ### Management - **Acute phase:** corticosteroids (prednisolone 1 mg/kg/day) ± immunosuppressants (methotrexate, azathioprine) - **Chronic phase:** low-dose steroids + immunosuppression - **Vascular complications:** percutaneous transluminal angioplasty or surgical bypass for critical stenoses [cite:Robbins 10e Ch 11]