Heart rate variability (HRV) in patients with atrial fibrillation (AF) is hardly studied. Though a reduced HRV in patients with heart failure and reduced ejection fraction (HFrEF) has been associated with poor prognosis. Data on HRV in AF-patients without a reduced ejection fraction is lacking. We hypothesize that those patients with persistent atrial fibrillation and larger beat-to-beat variability would be more symptomatic than does those with smaller HRV. To asses this theory we intend to perform a prospective observational trial. Symptoms of Atrial fibrillation will be assessed using Quality of Life questionnaires and 6 minutes walking test. Heart rate variability will be assessed using 24 hour Holter ECG monitoring.

The correlation between symptoms and heart rate variability will be then assessed.

Inclusion Criteria:

• Persistent atrial fibrillation
• No previous ablation for atrial fibrillation
• At least 18 years old
• Signed written patient's informed consent

Exclusion Criteria:

• Paroxysmal atrial fibrillation
• Previous ablation therapy for atrial fibrillation
• Reduced left ventricular ejection fraction (LVEF<35%)
• Permanent ventricular pacing (including cardiac resynchronization therapy CRT)
• Acute coronary syndrome (ACS) during past 6 weeks.
• Stroke or TIA within past 6 weeks.
• Cardiac surgical operation/ intervention within past 3 months.
• Acute decompensated heart failure
• Treatment with IV Inotropic medications (e.g. Dobutamine, Levosimendan)
• Mitral valve replacement or rheumatic mitral valve stenosis
• Neurological or psychological disease that may impair patient's judgement or compliance
• Pregnancy or Breast-feeding women.

Patients with persistent atrial fibrillation (defined as lasting more than seven days or requiring termination by cardioversion either with drugs or by direct current cardioversion) who are admitted at our clinic.