Atrial fibrillation is a cardiac arrhythmia of high prevalence in the population, especially in the elderly. Its main electrical characteristics are the interval between two successive irregular R waves, absence of P waves and presence of f waves between QRS complexes. The most common symptoms of atrial fibrillation are irregular palpitations associated with dyspnea, dizziness, feeling tired, fatigue and general malaise, but not all patients have any symptoms. The present report presents the history of an elderly patient who arrived at the hospital's emergency department with irregular heart rhythm and palpitations.