Long QTc Syndrome and Propionic Acidemia.

A 9-year-old boy diagnosed as Propionic acidemia at 2 months of age, complained of palpitations and nearsyncope episodes related with exercise. His metabolic condition was well controlled on sodium benzoate, carnitine, protein-free diet and biotin treatment. A prolonged QTc interval was noted on ECG-Holter (Fig. 1). Echocardiography showed no anomalies. He fulfilled criteria for diagnosis of Long QTc Syndrome (LQTS) [1], and treatment with propranolol was initiated with an observed decrease of the QTc interval to normal values. Acquired causes of LQTS were discarded, and genetic test was negative. At present he remains asymptomatic without cardiac events, and is under periodic follow-up.