No abstract

Objective -Using P-wave signal-averaged electrocardiography, we assessed the patterns of atrial electrical activation in patients with idiopathic atrial fibrillation as compared with patterns in patients with atrial fibrillation associated with structural heart disease. Atrial fibrillation is the most common sustained arrhythmia diagnosed in clinical practice [1][2][3][4] . In the general population, its prevalence increases with age: it is lower than 1% in the age bracket from 40 to 65 years, ranges from 2% to 5% in the age bracket from 65 to 74 years, and is higher than 5% above the age of 75 years. No difference in incidence has been observed between the sexes 1 . The increase in prevalence and incidence of atrial fibrillation with age is mainly associated with coexisting cardiac diseases. However, an independent effect of direct ageing on the atrial tissue cannot be excluded 5 . Methods -Eighty patients with recurrent paroxysmalA history of congestive heart failure, rheumatic valvar disease, left ventricular hypertrophy, and left atrial enlargement are independent risk factors associated with the genesis of atrial fibrillation. The presence of this arrhythmia in structurally normal hearts, although infrequent, may be detected in clinical practice. The triggering and maintenance factors of idiopathic atrial fibrillation are not very well defined. However, a significant number of patients with the paroxysmal or persistent form of atrial fibrillation, even though without evidence of anatomical cardiac alterations, evolve towards chronic atrial fibrillation. Such patients include those with structural heart disease despite the use of antiarrhythmic drugs. The objective of our study was to identify the electrophysiological behavior of atrial activation in patients with paroxysmal or persistent atrial fibrillation, through the use of P-wave signal-averaged electrocardiography for frequency-domain analysis. MethodsIn a cross-sectional study, we analyzed 80 patients who were being followed up in the outpatient cardiac arrhythmia care unit of the Hospital Universitário Pedro Ernesto. These patients had a history of at least 2 episodes of paroxysmal or persistent atrial fibrillation confirmed on electrocardiography in the last year, and they had not used any antiarrhythmic drug for at least 5 half-lives of each drug in