Author: Anna Hartzog, MD and Chinwe Unegbu, MD – Children’s National Hospital


A 3-month-old infant presents with tachypnea, poor weight gain, and diaphoresis with feeds. Parents deny any recent febrile illness. Chest radiograph demonstrates cardiomegaly and the electrocardiogram is notable for a QR pattern, ST segment depression, and T-wave inversion in leads I, II, and aVL. A transthoracic echocardiogram reveals severe left atrial dilation, severe mitral regurgitation, and left ventricular dysfunction with an EF of 15%-20% with preserved right ventricular function. Color flow doppler demonstrates retrograde flow in the left coronary artery. Four extremity blood pressures are normal. What is the MOST LIKELY diagnosis