Atrial fibrillation
Also calledAFib · AF · A-fib · atrial fibrillation
Definition
A supraventricular arrhythmia with uncoordinated atrial activation: discrete P waves are absent, the baseline shows irregular fibrillation waves (fine or coarse), and the R-R intervals are irregular when atrioventricular conduction is present. The fibrillation waves occur at about 350 to 600 per minute; only some of these impulses pass through the AV node, so the ventricular rate depends on AV conduction. Episodes are often triggered by rapidly firing ectopic foci; in a mapping study of 45 patients, 94% of the foci that started AF lay in the pulmonary veins.
Sources
- Page RL, Joglar JA, Caldwell MA, et al. 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia. Circulation. 2016;133(14):e506-e574. doi.org/10.1161/CIR.0000000000000311
- Haïssaguerre M, Jaïs P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998;339(10):659-666. doi.org/10.1056/NEJM199809033391003
- Goodacre S, Irons R. ABC of clinical electrocardiography: atrial arrhythmias. BMJ. 2002;324(7337):594-597. doi.org/10.1136/bmj.324.7337.594
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.