Myocardial Infarction in Neonates

Case Reports in Pediatrics
08 Nov, 2019 ,

This is case of a 4-day-old term baby who presented with respiratory distress and distal acrocyanosis. The chest radiograph demonstrated cardiomegaly without pleural effusion, and examination revealed hepatomegaly. An electrocardiogram revealed QS pattern in leads I, aVL, and V6, suggestive of ischemia. Cardiac enzymes were elevated, and echocardiogram revealed moderate left ventricular dysfunction with a thrombus at the level of the left atrial appendage. The patient required hemodynamic stabilization, vasodilatation to avoid congestive heart failure, and anticoagulation with heparin and aspirin.

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This is a full-term newborn (39 + 2 weeks of gestational age and a birth weight of 3270 grams), which is the result of third pregnancy of a healthy 36-year-old mother. After an uncomplicated pregnancy, the baby was delivered by spontaneous vaginal delivery with Apgar scores at 1 and 5 minutes of 9 and 10, respectively. The patient was discharged home completely asymptomatic at 2 days of life with exclusive breastfeeding.

At 4 days of life, he was admitted to a local hospital because of a 3-hour history of respiratory distress and distal acrocyanosis. Noninvasive respiratory support with continuous positive airway pressure was commenced, and umbilical venous catheterization was performed. Over the next several hours, the patient decompensated and became hypotensive. A heart murmur was noted on exam, so an echocardiogram was done, which showed left ventricular dysfunction, thrombus in the left atrium, and signs of pulmonary hypertension. The decision was made to transfer the patient to our hospital for further cardiology evaluation and management.

On arrival, the physical examination showed a nonreassuring general state, including pale/icteric color, perioral cyanosis, and tachypnea with subcostal retractions. Capillary refill was normal. Axillary and femoral pulses were present and symmetrical. Cardiac auscultation demonstrated a grade I/VI systolic murmur heard best at the left sternal border. The lungs were clear with good air entry. The abdomen was soft, with liver edge palpable 2 cm below the costal margin. The patient was hypoactive and hypotonic, with normal fontanelle and intact primitive reflexes.

Blood analysis performed at admission demonstrates moderately deranged liver function (AST 62 U/L, ALT 118 U/L, and CRP 15.3 mg/L) and markedly elevated cardiac enzymes (troponin T: 4,046 ng/L, proBNP >35,000 pg). D-dimer was 1.621 ng/mL. Chest X-ray showed cardiomegaly without pleural effusion. Electrocardiogram (ECG) showed a QS pattern in leads I, aVL, and V6, and echocardiogram confirmed normal intracardiac and coronary anatomy, moderate left ventricular dysfunction (EF 45%), and a thrombus at the level of the left atrial appendage, leading to the working diagnosis of acute myocardial infarction, possibly secondary to the atrial thrombus.

Hemodynamic stabilization was performed with volume expanders and milrinone infusion. Unfractionated heparin was started initially and then subsequently converted to low-molecular-weight heparin plus aspirin for full anticoagulation. Further investigations show no evidence of thrombophilia, and septic screen was negative. In follow-up echocardiograms, cardiac function showed almost complete recovery, and the patient was discharged at 26 days of age on captopril, furosemide, spironolactone, enoxaparin, and aspirin. Catheterization performed one month later did not show any lesion or abnormality in the coronary arteries, with a normal EF. Medications were gradually weaned off, and he had no further concerns.