An 18-year-old man is admitted to the hospital with acute onset of substernal chest pain that began abruptly 30 minutes ago. He repos the pain radiating to his neck and right arm. He has otherwise been in good health. On physical examination, he is diaphoretic and tachypnoeic. His BP is 102/48 mmHg and hea rate is 112 bpm, regular rhythm but is tachycardiac. A 2/6 holosystolic murmur is heard best at the apex and radiates to the axilla. His lungs have bilateral rales at the bases. The ECG demonstrates 4 mm of ST elevation in the anterior leads. In the past he was hospitalized for some problem with his hea when he was 4 years old. His mother, who accompanies him, repos that he received aspirin and g- globulin as treatment. Since that time, he has required intermittent follow-up with echocardiography. What is the most likely cause of this patient’s acute coronary syndrome?

**Core Concept**
Kawasaki disease is a rare, acute, febrile vasculitis that predominantly affects children, but can persist into adulthood. It is characterized by inflammation of the coronary arteries, which can lead to aneurysm formation and increased risk of atherosclerosis and subsequent coronary artery disease.

**Why the Correct Answer is Right**
This patient's history of Kawasaki disease at age 4, which required hospitalization and treatment with aspirin and gamma-globulin, is highly suggestive of the current presentation. The development of coronary artery aneurysms in Kawasaki disease increases the risk of premature atherosclerosis and subsequent coronary artery disease, which can manifest as acute coronary syndrome (ACS) in adulthood. The presence of a 2/6 holosystolic murmur radiating to the axilla, indicative of aortic regurgitation, may also be related to the long-term consequences of Kawasaki disease. The ECG findings of ST elevation in the anterior leads are consistent with an acute coronary event.

**Why Each Wrong Option is Incorrect**
**Option A:** **Acute Myocardial Infarction due to Atherosclerotic Disease** - While atherosclerotic disease is a common cause of ACS, this patient's age and history of Kawasaki disease make it less likely.

**Option B:** **Vasculitis** - While Kawasaki disease is a form of vasculitis, the patient's current presentation is more consistent with an acute coronary event rather than a systemic vasculitic process.

**Option C:** **Cardiomyopathy** - There is no evidence to suggest that the patient has a cardiomyopathy, and the ECG findings are more consistent with an acute coronary event.

**Option D:** **Pericarditis** - While pericarditis can present with ST elevation on ECG, the patient's history of Kawasaki disease and the presence of a holosystolic murmur make ACS a more likely diagnosis.

**Clinical Pearl / High-Yield Fact**
Kawasaki disease is a rare but important cause of coronary artery disease in children and young adults, and patients with a history of Kawasaki disease should be screened for coronary artery abnormalities and followed closely for signs of premature atherosclerosis.

**Correct Answer:** C. **Kawasaki disease**

✓ Correct Answer: C. Thrombosis of a coronary aery aneurysm