Mecanismos electrofisiológicos y diagnóstico de la fibrilación auricular

Despite being the most common sustained cardiac arrhythmia and despite having been first described over 100 years ago, atrial fibrillation is, like ventricular fibrillation, virtually the only arrhythmia whose mechanism is still unknown. This lack of knowledge has profound clinical implications and is not just of academic interest. Firstly, lack of knowledge means that the diagnosis of atrial fibrillation is still based on ECG findings, which can often give rise to doubts about the diagnosis, with both surface ECGs and intracardiac electrophysiological studies. Moreover, lack of knowledge about the underlying mechanism also hampers the development of both better-targeted pharmacological and invasive therapies and preventive measures that can avert, or at least delay, the onset of atrial fibrillation. This article provides a review of the most widely accepted theories about the mechanism underlying this arrhythmia, such as the multiple coexisting functional re-entry circuits theory and the mother rotor theory. In addition, the article examines factors that could influence the condition, such as atrial remodeling, atrial fibrosis and scarring, and the critical atrial mass, and considers the role of the pulmonary veins and the evidence supporting a link with re-entry. Diagnostic criteria for this arrhythmia, its classification and recommended diagnostic investigations are also discussed.