Lethal cardiac tachyarrhythmia in a patient with neonatal carnitine-acylcarnitine translocase deficiency

Carnitine-acylcarnitine translocase (CACT) deficiency is an inherited defec t of the co-transport of free and esterified carnitine across the inner mit ochondrial membrane. We report a case of CACT deficiency in a newborn who d ied at 72 h of age from severe, intractable cardiac tachyarrhythmia, despit e an improvement in his neurological and biochemical status. Postmortem exa mination showed marked steatosis of myocardium, liver, and kidney. In addit ion, electron microscopic studies showed virtually complete elimination of mitochondria from cardiomyocytes. It appears that the correction of the acu te metabolic derangements in this condition may not prevent rapid progressi on to death, suggesting that the rhythm disturbances in CACT deficiency res ult from prior and ongoing accumulation of toxic metabolites, rather than f rom an acute metabolic derangement. Furthermore, we speculate that the choi ce of anti-arrhythmic agent in this patient may paradoxically have contribu ted to his death.