Atrial fibrillation (AF) is the most common clinical arrhythmia. AF is associated with increased risk for stroke due to blood clots formed in the fibrillating atria. Some patient characteristics increase the likelyhood of AF and at the same time the risk of stroke when AF has developed. To reduce the risk of stroke, anticoagulation therapy is recommended in patients with AF and risk factors (such as high blood pressure, diabetes, vessel disease). However, occasional (paroxysmal) AF may occur without symptoms and remain undetected, leaving patients at risk.

Aim of the prospective randomized study is to compare two management strategies for patients at increased risk for AF but without a known history of AF. Patients are seen regularly (monthly, then quarterly) for follow-up (incl. ECG recording and blood sample). One group of patients additionally receives a subcutaneous implantation of a loop recorder for continuous rhythm monitoring, while the control group remains on standard follow-up. Observation period is one year (optional extension for 3 years). The time to first diagnosis of AF is compared between groups, blood samples are analyzed for potential biomarkers of AF.

Inclusion Criteria:

• CHA2DS2-VASc risk score >= 4*
• 18 years or older

Exclusion Criteria:

• known history of atrial fibrillation
• implanted rhythm device
• pre-existing indication for oral anticoagulation

(*)CHA2DS2-VASc: C - chronic heart failure (1 point); H - hypertension (1 point); A - age >= 75 years (2 points); D - diabetes (1 point); S - stroke (2 points); V - vascular disease (1 point); A - age >=65 and < 75 years (1 point); Sc - sex category (female) (1 point) ;