A 74 year-old female patient was admitted to emergency service with a complaints of dizziness and shortness of breath. Complete atrioventricular block was observed and patient was followed up two days with transient transvenous cardiac pacemaker. Afterthat, atrial fibrillation (AF) was progressed and then, coronary angiography was scheduled. Although all three main coronary arteries was free of the stenotic lesion and coronary ectasia, there was a local ectatic segment with prominent slow flow in the sinoatrial node artery that originated from proximal right coronary artery. Patient was treated with dual anti-agregants and enoxaparine in the hospitalization period. Bradiarrhtymias did not recur and AF was reverted to sinusal rhythm with medical therapy. Classical risk factors for AF progression was absent in the patient. We thought that, ectasia and slow flow in the sinoatrial node artery could trigger the bradiarrhtymia and AF by the mechanism of ischemic sinus node dysfunction.