Prolonged QT interval (>450) is reported in 3 of 20 pediatric epilepsy patients (mean age 9.8 +/- 4.7 years) treated with the ketogenic diet at the University of Cincinnati, OH. The duration of the diet was 13 +/- 8 months, and the initial fat to nonfat calorie ratio was 4:1. Vitamins, minerals, selenium, and carnitine supplements were added. Two patients with QT intervals >500 had left atrial and ventricular enlargement. Calcium levels were normal. Pronged QT was significantly correlated with low serum bicarbonate and high betahydroxybutyrate. When the diet was discontinued in one patient, the QT abnormality and cardiomyopathy resolved. 
COMMENT. Children treated with the ketogenic diet in the 4:l/ketogenic:antiketogenic ratio should receive ECGs and echocardiograms before and during therapy. This cardiac complication is a further indication of the need to reassess the relatively high fat content of the Hopkins ketogenic diet. As previously indicated, the original Mayo Clinic method of introduction of the diet, with much lower fat/CH ratios, is effective and with fewer side reactions (Ped Neur Briefs August 1998;12:61).