Adenosine A2A receptor antagonists are useful for the preparation of medicaments against atrial fibrillation in mammals, including humans. It has been found that the adenosine A2A receptor is present in human atrial cardiomyocytes and participates in the pathological mechanisms underlying atrial fibrillation. An advantage of using A2A antagonists over other agents known in the art is that the A2A antagonists specifically target patients with atrial fibrillation.