Prolonged QTc interval in association with medium-chain acyl-coenzyme A dehydrogenase deficiency

Abstract

Medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency is the most common disorder of mitochondrial fatty acid oxidation. We report a term male infant who presented at 3 days of age with hypoglycemia, compensated metabolic acidosis, hypocalcemia, and prolonged QTc interval. Pregnancy was complicated by maternal premature atrial contractions and premature ventricular contractions. Prolongation of the QTc interval resolved after correction of metabolic derangements. The newborn screen was suggestive for MCAD deficiency, a diagnosis that was confirmed on genetic analysis that showed homozygosity for the disease-associated missense A985G mutation in the ACADM gene. This is the first report of acquired prolonged QTc in a neonate with MCAD deficiency, and it suggests that MCAD deficiency should be considered in the differential diagnoses of acute neonatal illnesses associated with electrocardiographic abnormality. We review the clinical presentation and diagnosis of MCAD deficiency in neonates.

Keywords: MCAD; medium-chain acyl-coenzyme A dehydrogenase deficiency; neonate; prolonged QT.

FIGURE 1

A, ECG leads of rhythm obtained on the day of presentation that show prolonged QTc interval (25 mm/second, 10 mm/millivolt; R-R = 468 milliseconds, QT = 354 milliseconds, QTc = 517 milliseconds). B, Normal ECG obtained on the 41st day of life indicative of resolution of prolonged QTc interval (25 mm/second, 10 mm/millivolt; R-R = 366 milliseconds, QT = 244 milliseconds, QTc = 403 milliseconds).