In an adolescent or young adult with a history of Kawasaki disease and clinical or stress‑test evidence of significant coronary artery disease (or inadequate echocardiographic visualization), is CT coronary angiography the preferred first‑line non‑invasive imaging test?

CT Coronary Angiography in Kawasaki Disease with Suspected Significant Coronary Artery Disease

In adolescents and young adults with a history of Kawasaki disease and clinical or stress-test evidence of significant coronary artery disease, CT coronary angiography is the preferred first-line non-invasive imaging test when echocardiography is inadequate or inconclusive. 1

Primary Imaging Strategy

Echocardiography remains the initial imaging modality for all Kawasaki disease patients due to its high sensitivity and specificity for proximal coronary segments. 1, 2 However, this population presents unique challenges:

• Visualization becomes progressively more difficult as body size increases, making echocardiography increasingly limited in adolescents and young adults 1, 2
• Echocardiography has unclear sensitivity and specificity for detecting coronary stenosis and thrombosis, the exact pathology suspected in patients with positive stress tests 1, 2
• Distal coronary segments are poorly visualized by echocardiography, yet these are critical areas for stenotic lesions years after acute disease 1, 2

When CT Coronary Angiography Becomes First-Line

CT coronary angiography is currently the most useful imaging modality for comprehensive coronary evaluation in Kawasaki disease. 1 The 2023 ACR Appropriateness Criteria explicitly state that since the advent of CT angiography, invasive coronary angiography has become second-line for Kawasaki disease. 1

Specific Advantages in This Population

• CT provides superior visualization of the entire coronary tree including distal segments that are critical for detecting stenoses in adolescents/young adults with remote Kawasaki disease 1
• CT accurately identifies stenoses, thromboses, and calcifications that echocardiography cannot reliably detect 1, 3, 4
• CT detects non-obstructive coronary artery disease (both calcified and non-calcified plaque) that is almost always associated with normal stress imaging but represents future risk 4
• CT visualizes the left circumflex artery in 100% of cases, whereas echocardiography consistently fails to image this vessel 3, 5

Evidence Supporting CT as First-Line

Recent research demonstrates CT's superiority in this exact clinical scenario:

• In a 2020 study, CT identified 34 aneurysms (56% of total) with Z-scores >3 that were completely missed by echocardiography, and CT findings resulted in immediate treatment changes in 5 patients 3
• CT detected 23 lesions not diagnosed by echocardiography in a 2019 study, including aneurysms, ectasias, and stenoses, particularly in distal and posterior segments 6
• Calcifications were visualized as early as 2.7 years after disease onset on CT, providing prognostic information unavailable from other non-invasive modalities 3
• In a 2024 study of 225 children, CT detected left circumflex lesions in 18.2% of patients, but echocardiography detected only 36.6% of these lesions, with all thromboses and stenoses missed by echocardiography 5

Radiation Considerations

Modern third-generation dual-source CT scanners achieve median effective doses of 1.5 mSv (range 0.3-9.4 mSv), significantly lower than older scanners and comparable to natural background radiation exposure 3, 7. This low radiation burden is acceptable given the high-risk nature of this population and the critical diagnostic information obtained. 3

When Invasive Angiography Is Still Needed

Invasive coronary angiography should be reserved for:

• Interventional procedures (catheter-based treatment or surgical planning) 1
• When CT or MRI findings are inconclusive 1
• Fractional flow reserve assessment to determine functional significance of stenoses 1
• Evaluation of treatment efficacy after revascularization procedures 1

Critical Pitfalls to Avoid

• Do not rely on echocardiography alone in adolescents/young adults with suspected significant disease, as body size severely limits visualization and stenoses are frequently missed 1, 2, 3
• Do not assume normal stress testing excludes significant coronary pathology, as non-obstructive disease and early stenoses are often present despite normal functional studies 4
• Do not delay CT imaging waiting for invasive angiography, as CT provides comprehensive anatomic detail non-invasively and can guide whether invasive procedures are needed 1, 3
• Ensure CT is performed on modern dual-source scanners to minimize radiation exposure while maintaining diagnostic quality 3, 7