This research will investigate the PPG signal morphology related to physiological and non- physiological changes in arrhythmia-related heart rate as well as the performance of the PPG-based features previously developed within the framework of the Mini-Holter study to discriminate between several cardiac arrhythmias. To this end, clinical data will be recorded on patients by using a wrist-based PPG monitor simultaneously with 12-lead ECG and intracardiac electrogram (EGM) signals at the university hospital in Lausanne. Importantly, this study will remain purely observational as it will not change the diagnostic and therapeutic management of the included patients, nor will it interfere with the time course of the procedures. The aim of enHEART study is to validate on a larger database the ability of several previously developed PPG-based features to detect a variety of cardiac arrhythmias.