Introduction: Long QT syndrome is characterised by an alteration in cardiac repolarisation that brings about ventricular arrhythmias. The resulting cerebral hypoxia leads to fainting and convulsions that, in up to 10% of cases, are interpreted as epilepsy.
Case report: We report the case of a patient of paediatric age who was affected by an isolated presentation of congenital long QT syndrome, which had initially been diagnosed as idiopathic epilepsy, and who suffered a sudden loss of consciousness while doing exercise. The initial electrocardiographic monitoring revealed a ventricular tachycardia in torsades de pointes, which was reversed by advanced cardiopulmonary revival manoeuvres. At 12 days after admission, there was an absence of electrical brain activity and brain death resulted.
Conclusion: The high mortality among symptomatic patients affected by long QT syndrome and the effectiveness of the treatment highlight the importance of a correct diagnosis. A detailed clinical history and an electroencephalogram with a simultaneous electrocardiogram (ECG) recording, together with continuous EEG recording for 24 hours, with the manual evaluation of the corrected QT, would all help in the identification of unsuspected cases. A complete study of the family, including the possible associated mutations, could be a new form of early diagnosis.