Development Of Persistent Atrial Fibrillation Research Articles

Multiple Arrhythmogenic Foci Associated With the Development of Perpetuation of Atrial Fibrillation

The presence of multiple arrhythmogenic sources may be associated with the perpetuation of atrial fibrillation (AF). In this study, we investigated the hypothesis that multiple foci might be involved in the development of AF persistency. Two hundred fourteen consecutive patients with AF undergoing catheter ablation were enrolled in this study. The location of the arrhythmogenic foci was determined using simultaneous recordings from multipolar catheters before and after pulmonary vein isolation during an isoproterenol administration. We detected 500 arrhythmogenic foci (263 foci as AF initiators, and 237 foci as non-AF initiators). High-dose isoproterenol infusions (ranging from 2 to 20 microg/min) revealed potential arrhythmogenic foci, especially non-pulmonary vein foci (55%). Persistent AF was more highly associated with an incidence of multiple (>2) foci than paroxysmal AF (88% versus 65%, P=0.002), and a multivariate analysis demonstrated that multiple foci (>2) were an independent contributing factor for persistent AF (odds ratio; 95% confidence interval, 4.69; 1.82 to 12.09, P<0.001). In paroxysmal AF, the number of foci was higher in patients with long-term AF (>24 hours) than in those with short-lasting AF (2.64+/-0.14 versus 1.77+/-0.16, P=0.001). In the persistent AF group, the patients with short-lasting AF (<12 months) had a greater number of foci than did those with long-term AF (>12 months) (3.62+/-0.15 versus 1.92+/-0.16, P=0.04). Multiple foci were likely to be involved in the development of persistent AF. However, if AF persisted for >12 months, they may not have had a significant effect on the AF perpetuation.

Minimizing Ventricular Pacing to Reduce Atrial Fibrillation in Sinus-Node Disease

Conventional dual-chamber pacing maintains atrioventricular synchrony but results in high percentages of ventricular pacing, which causes ventricular desynchronization and has been linked to an increased risk of atrial fibrillation in patients with sinus-node disease. We randomly assigned 1065 patients with sinus-node disease, intact atrioventricular conduction, and a normal QRS interval to receive conventional dual-chamber pacing (535 patients) or dual-chamber minimal ventricular pacing with the use of new pacemaker features designed to promote atrioventricular conduction, preserve ventricular conduction, and prevent ventricular desynchronization (530 patients). The primary end point was time to persistent atrial fibrillation. The mean (+/-SD) follow-up period was 1.7+/-1.0 years when the trial was stopped because it had met the primary end point. The median percentage of ventricular beats that were paced was lower in dual-chamber minimal ventricular pacing than in conventional dual-chamber pacing (9.1% vs. 99.0%, P<0.001), whereas the percentage of atrial beats that were paced was similar in the two groups (71.4% vs. 70.4%, P=0.96). Persistent atrial fibrillation developed in 110 patients, 68 (12.7%) in the group assigned to conventional dual-chamber pacing and 42 (7.9%) in the group assigned to dual-chamber minimal ventricular pacing. The hazard ratio for development of persistent atrial fibrillation in patients with dual-chamber minimal ventricular pacing as compared with those with conventional dual-chamber pacing was 0.60 (95% confidence interval, 0.41 to 0.88; P=0.009), indicating a 40% reduction in relative risk. The absolute reduction in risk was 4.8%. The mortality rate was similar in the two groups (4.9% in the group receiving dual-chamber minimal ventricular pacing vs. 5.4% in the group receiving conventional dual-chamber pacing, P=0.54). Dual-chamber minimal ventricular pacing, as compared with conventional dual-chamber pacing, prevents ventricular desynchronization and moderately reduces the risk of persistent atrial fibrillation in patients with sinus-node disease. (ClinicalTrials.gov number, NCT00284830 [ClinicalTrials.gov].).

295 Decreased fractional area change of left atrial appendage contributes to development of persistent atrial fibrillation in patients of lone paroxysmal atrial fibrillation

295 Decreased fractional area change of left atrial appendage contributes to development of persistent atrial fibrillation in patients of lone paroxysmal atrial fibrillation

Fibrillatory wave size in paroxysmal atrial fibrillation.

Little attention has been paid to the atrial fibrillatory waves (f waves) in paroxysmal atrial fibrillation. The present study attempted (1) to compare the f wave size in paroxysmal atrial fibrillation with that in persistent fibrillation, and (2) to examine whether the f wave size can predict the development of persistent from paroxysmal atrial fibrillation. The size of the f waves was measured in 60 patients with paroxysmal atrial fibrillation of non-rheumatic etiology (group A), 87 patients with persistent atrial fibrillation of non-rheumatic etiology (group B), and 34 patients with persistent atrial fibrillation of rheumatic etiology (group C). The f wave size in group A was 1.1 +/- 0.1 mm (mean +/- SE) which was significantly smaller than 1.6 +/- 0.1 mm in group B and 2.2 +/- 0.2 mm in group C (p less than 0.01, respectively). Among patients with paroxysmal atrial fibrillation, persistent atrial fibrillation developed in 9 of 19 patients (47.4%) with f wave size of 1.2 mm or more, and only in 5 of 41 patients (12.2%) with f wave size of less than 1.2 mm. These results indicate that paroxysmal atrial fibrillation generally has smaller f waves than persistent atrial fibrillation, but that the presence of larger f waves indicates potential development of persistent atrial fibrillation.