Atrial fibrillation is characterized by rapid, irregular activation of the atria. Causes can include reentry and abnormal automaticity. Atrial fibrillation is one of the most commonly seen supraventricular arrhythmias. AF can be paroxysmal or chronic. Chronic AF often causes a markedly elevated ventricular response rate and thereby contributes to the clinical signs of heart failure. AF also can occur in the absence of overt structural heart disease as lone AF, which can feature a normal or mildly elevated ventricular response rate.

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