The subjects will be asked to place a smartwatch on each arm to allow their pulse curve to be recorded for five minutes. At the same time, an ambulatory ECG system will take a synchronous ECG for reference. The ECG system employed is equipped with a validated automatic atrial fibrillation detector, used as a reference for assignment to groups. Data will be collected on person-related information, comorbidities and medication (estimated overall duration/patient <20 min). No follow-up is planned. Analogous to predecessor studies, the pulse wave curve data are coded with the patient's identification number (ID) and externally analyzed at Preventicus; based on the results, the patients will be assigned to SR/AF groups. After evaluation of all files, the grouped results will be aggregated, unblinded and evaluated under monitoring.