Clinical Scenario:
A 3-month-old previously well infant presents with episodes of inconsolable crying, sweating, and pallor during feeding, along with poor weight gain. On examination: HR 160/min, RR 56/min, and a soft apical systolic murmur. ECG shows deep, wide Q waves with ST elevation in leads I and aVL. Chest X-ray shows cardiomegaly. Echocardiography reveals a dilated left ventricle with reduced ejection fraction, moderate mitral regurgitation, and retrograde flow noted in a dilated right coronary artery.
What is the most likely diagnosis?
A. Anomalous left coronary artery from pulmonary artery
B. Dilated cardiomyopathy
C. Kawasaki disease with coronary aneurysm
D. Myocarditis
E. Supravalvular aortic stenosis
Correct answer & Explanation:
Correct Answer: A — Anomalous left coronary artery from pulmonary artery (ALCAPA)
Explanation:
Why A is correct: The classic presentation of ALCAPA is an infant with episodes resembling anginal pain during feeding (crying, sweating, pallor — feeding requires increased cardiac work), along with heart failure symptoms. The ECG finding of deep Q waves and ST elevation in leads I and aVL reflects lateral wall myocardial ischemia/infarction from anomalous coronary perfusion. Echo showing retrograde flow in a dilated right coronary artery (compensatory collateral flow feeding the anomalous left coronary via collaterals, then draining into the low-pressure pulmonary artery) is a hallmark diagnostic finding.
Why others are wrong:
- B — Dilated cardiomyopathy can mimic ALCAPA on echo (dilated LV, low EF), but it does not explain the anginal-equivalent symptoms during feeding or the specific ECG pattern of lateral wall infarction.
- C — Kawasaki disease typically occurs after 6 months of age with fever and mucocutaneous features; coronary aneurysms, not anomalous origin, are seen, and the classic ECG pattern here would be absent.
- D — Myocarditis can cause similar echo findings but usually follows a viral prodrome and lacks the specific ECG pattern of fixed lateral ischemia; feeding-related “anginal” episodes are not typical.
- E — Supravalvular aortic stenosis causes an ejection systolic murmur and is associated with Williams syndrome, not this ischemic ECG pattern or feeding-related symptoms.
