Arrhythmogenic syncopes can clinically resemble epileptic seizures ("convulsive syncope"). During basic work-up of syncope, the 12 lead ECG may provide valuable clues indicating an arrhythmogenic cause of syncope, showing excitation as well as repolarisation abnormalities. If an arrhythmogenic cause of syncope is suspected but ECG documentation as a proof of diagnosis is missing, implantation of an ILR can be useful. In LQTS, multiple gene mutations are known but cover only a fraction of clinical LQTS.