International consensus on nomenclature and classification of atrial fibrillation. A collaborative project of the Working Group on Arrhythmias and the Working Group on Cardiac Pacing of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology

Atrial fibrillation (AF) has in recent years been the subject of intense investigation in terms of obtaining a better understanding of its mechanism and improving its management. Despite the advances made, AF remains a challenge for the clinician, and it is uncertain whether these theoretical advances have resulted in a significant improvement in the way the vast majority of patients are managed in general practice. Several reasons may account for this situation. One possible reason is incomplete knowledge of the complex mechanism of this common arrhythmia. Another possible reason is the heterogeneous clinical presentation of the arrhythmia. Still, the numerous publications and clinical trials devoted to AF have dealt with this arrhythmia as if it were a single entity. Furthermore, the abundant terminology used to characterize various subsets of AF and the absence of consistency in the definitions have added to the difficulty in communication.1 Consequently, it has become difficult to compare the results of pharmacologic or nonpharmacologic therapies because different classifications have been used, and the difficulty in characterizing the patient population has not allowed easy or appropriate comparison. The Working Group of Arrhythmia of the European Society of Cardiology (WGA-ESC) and the North American Society of Pacing and Electrophysiology (NASPE) have recognized the need to create a Study Group in an attempt to achieve a consensus on the terminology and classification of AF. This document reports the conclusions reached by this Study Group during a meeting held on June, 13, 2000, and completed by the members soon thereafter. The definitions and classification resulting from this consen-