Using implantable loop recorder the investigators wish to detect atrial fibrillation in high risk patients and compare it to the results using conventional Holter monitoring. The hypothesis is that 10-15% of high risk patients have subclinical atrial fibrillation. The investigators want to detect those people so they can receive appropriate anticoagulation treatment. The patients will get a comprehensive workup including ecg, echocardiography and blood tests.

Inclusion Criteria:

• age > 65 years
• arterial hypertension (at least dual treatment)
• diabetes mellitus (oral antidiabetics or insulin)

Exclusion Criteria:

• known atrial fibrillation
• ischaemic heart disease
• Current anticoagulation treatment
• Ejection fraction <45 %
• significant valvular heart disease
• previous stroke/transient ischemic attack
• peripheral arterial disease
• end stage renal disease
• thyreotoxicosis