 Patients with difficult-to-treat epilepsy refractory epilepsy are at high risk of sudden death: sudden unexpected death in epilepsy SUDEP. Cardiac arrhythmias are one of the possible causes of SUDEP. When monitoring in the hospital setting, the frequency of cardiac arrhythmias in people with epilepsy is low: 0,4. However, when a subcutaneous implantable device Reveal XT is used to monitor heart rhythm continuously for an extended period of time, the frequency of clinically relevant arrhythmias appeared much higher in two small observational studies n19: 6-20. The aim of this study is to analyze the frequency and underlying mechanism of cardiac arrhythmias in a larger group of 50 people with refractory epilepsy with Reveal XT. In the future, this may help us to identify those epilepsy patients at high risk of cardiac arrhythmias, so that we can timely institute preventive measures e.g. pacemaker implantation. 