BIO|CONCEPT.BIOMONITOR III

Inclusion Criteria: * Patient is at high risk of developing a clinically important cardiac arrhythmia; or Patient is undergoing investigation for symptoms such as palpitations, pre-syncope or syncope, that are suggestive of an underlying cardiac arrhythmia; or Patient is undergoing investigation for the detection of atrial fibrillation following cryptogenic stroke; or Patient is planned for AF ablative procedure or has already undergone an AF ablative procedure. * Patient is able to understand the nature of study and has provided written informed consent. * Patient is willing and able to perform all follow up visits at the study site. * Patient is willing and able to use the CardioMessenger and accepts the BIOTRONIK Home Monitoring concept. Exclusion Criteria: * Patients implanted with ICD or pacemaker. * Patient is pregnant or breast feeding. * Patient is less than 18 years old. * Patient is participating in another interventional clinical investigation * Patient´s life-expectancy is less than 6 months.