[Value of electrophysiological studies in the evaluation of atrial fibrillation].

Electrophysiological studies of the atrium provide a means of evaluating the parameter involved in the process of fibrillation. The study of atrial vulnerability, initially limited to the test of provocation of the arrhythmia, has widened to include analysis of the substrate. Shortened refractory periods and regional conduction defects play a role in the creation of reentry pathways. Variations in the heart rate influence these parameters and explain the fundamental role of the autonomic nervous system on the uniformity of the activation front. The risk of atrial fibrillation is related essentially to thrombo-embolism: atrial vulnerability was investigated in 70 patients with unexplained cerebrovascular accidents. Globally, one out of two patients had pathological substrates. This study of atrial vulnerability showed that it was possible to identify a group of patients at risk of atrial fibrillation, even before the arrhythmia was recorded. This prognostic approach could also be applied to the investigation of preexcitation and syncope, and to the evaluation of the effects of pharmacological intervention.