Kawasaki disease and coronary complications — branching viva

Examiner opening (Examiner)

You are the general paediatric registrar in the emergency department. An eighteen-month-old child is brought in febrile and irritable, on day six of fever, with bilateral red eyes without discharge, cracked bleeding lips, a strawberry tongue, a widespread rash, and swollen red palms and soles. Talk me through your assessment and immediate management. [1]

Exemplar opening (Candidate)

This child has a clinical picture strongly suggestive of Kawasaki disease, and because we are on day six of fever the ten-day treatment window is open but narrowing, so I will move quickly. I will confirm the fever duration and the five principal features — bilateral non-purulent conjunctivitis, oral changes, polymorphous rash, extremity changes, and cervical lymphadenopathy — and he already has four of five with the fever, which is complete Kawasaki disease. I will take blood for a full blood count, C-reactive protein, erythrocyte sedimentation rate, albumin and liver function, send a urine for microscopy, and arrange a baseline echocardiogram. While those are running I will start intravenous immunoglobulin at 2 g/kg as a single infusion over ten to twelve hours with high-dose aspirin, because treating within ten days is the single biggest factor preventing coronary aneurysms. [1]

Branch 1 — the disease and the criteria (Examiner)

What is Kawasaki disease, and what makes it incomplete, and why does that matter for the coronaries? [1]

Exemplar (Candidate)

Kawasaki disease is an acute, self-limited febrile vasculitis of medium muscular arteries with a striking tropism for the coronary arteries, and it is the leading cause of acquired heart disease in children in high-income countries. Complete disease is fever for five days or more plus four or five of the five principal features. Incomplete disease is fever with only two or three features, and it matters because it is commonest in infants under six months and in older children, the diagnosis is delayed, and the coronary risk is at least as high. The principle is to treat on suspicion using supportive laboratory criteria and the echocardiogram rather than wait for the full picture. [1]

Branch 2 — treatment and its evidence (Examiner)

You have decided to treat. Give me the regimen, the timing, and the evidence behind it. [2]

Exemplar (Candidate)

The regimen is intravenous immunoglobulin at 2 g/kg as a single infusion over ten to twelve hours, together with high-dose aspirin at 30 to 50 mg/kg per day, given as early as possible and ideally within ten days of fever onset. When he is afebrile the aspirin steps down to an anti-thrombotic dose of 3 to 5 mg/kg per day until the coronaries are normal at six to eight weeks. The evidence is the landmark 1986 trial showing that IVIG plus aspirin reduced coronary aneurysms from about a quarter of children to under five per cent, and the 1991 trial showing a single 2 g/kg infusion was superior to four smaller infusions. Those trials are why the single-dose regimen within ten days is standard. [2]

Branch 3 — reassessment and resistance (Examiner)

The child is still febrile 40 hours after the IVIG. What does that mean and what do you do? [3]

Exemplar (Candidate)

Persistent or recurrent fever 36 to 48 hours after IVIG defines IVIG-resistant disease, which affects about fifteen per cent of children and marks the group at highest risk of coronary aneurysms. I will escalate to a second dose of IVIG at 2 g/kg or infliximab at 5 to 10 mg/kg. The KIDCARE randomised trial compared infliximab with a second IVIG and found infliximab shortened fever duration and length of stay with a comparable coronary outcome, which has shifted many centres toward infliximab as the first second-line agent. I will repeat the echocardiogram and trend the inflammatory markers, and if he remains refractory I will involve the specialists to add corticosteroids or other adjuncts such as ciclosporin, anakinra, etanercept or plasma exchange. [3]

Branch 4 — coronary complications and grading (Examiner)

His echocardiogram shows a coronary aneurysm with a z-score of seven. How do you grade coronary involvement and how does it change management? [4]

Exemplar (Candidate)

Coronary involvement is graded by z-score, which is a standard-deviation score adjusted for body surface area. Dilation alone is a z-score from 2.0 to 2.5, a small aneurysm is 2.5 to under 5, a medium aneurysm is 5 to under 10 or an absolute diameter under eight millimetres, and a giant aneurysm is a z-score of ten or more or an absolute diameter of at least eight millimetres. His z-score of seven is a medium aneurysm. The grading drives anti-thrombotic intensity: small aneurysms are managed with low-dose aspirin alone, medium aneurysms often warrant aspirin plus an anti-platelet agent such as clopidogrel, and giant aneurysms require anticoagulation in addition to anti-platelet therapy. I will match his therapy to the z-score and arrange serial echocardiography. [4]

Branch 5 — long-term outlook (Examiner)

Fast-forward. He has a giant aneurysm that has not regressed. What is his long-term risk and how do you surveil him? [5]

Exemplar (Candidate)

The long-term risk is that giant aneurysms persist and may progress to stenotic lesions or thrombus, producing ischaemia or myocardial infarction years to decades later — Kawasaki disease is a leading cause of myocardial infarction in young adults with a childhood cardiac history. I will commit him to lifelong surveillance with serial echocardiography, exercise testing and coronary imaging such as computed tomography or magnetic resonance angiography to detect stenosis, thrombus and ventricular function. His anti-thrombotic therapy combines anticoagulation with anti-platelet agents because of the high thrombotic risk, and any chest pain or syncope is ischaemia until proven otherwise. He will need a structured transition to adult cardiac care in adolescence. [5]

Branch 6 — incomplete disease in infants (Examiner)

A four-month-old infant presents with fever and irritability but only one clinical feature. How does your approach change? [1]

Exemplar (Candidate)

Infants under six months most often present with incomplete disease, are most vulnerable to aneurysms, and are most likely to be missed, so my threshold to investigate and treat is lower. I will check the full inflammatory panel and arrange an echocardiogram, and if the inflammatory markers are raised and there is no alternative diagnosis I will treat on suspicion with IVIG and aspirin using the supplementary laboratory criteria, because waiting for the full picture risks missing the ten-day window. The cost of a missed early window is a preventable aneurysm, and in this age group that cost is highest. [1]

Examiner wrap-up (Examiner)

Thank you. Summarise the three points you most want the examiner to remember. [1]

Exemplar (Candidate)

First, Kawasaki disease is a clinical diagnosis — fever five days or more plus four of five principal features — and incomplete disease, especially in infants, is treated on suspicion with supportive labs and echo. Second, treat within ten days with IVIG 2 g/kg and aspirin, which cuts aneurysms from about a quarter to under five per cent, and escalate for IVIG resistance at 36 to 48 hours to infliximab or a second IVIG. Third, coronary aneurysms are graded by z-score and giant aneurysms carry a lifelong risk of thrombosis, stenosis and myocardial infarction, so these children need anti-thrombotic therapy and surveillance for life, and any chest pain or syncope is ischaemia until proven otherwise. [1] [5]