Frequency, duration, and predictors of newly-diagnosed atrial fibrillation following dual-chamber pacemaker implantation in patients without a previous history of atrial fibrillation.

The Silent Atrial Fibrillation Detection With Stored EGMs (SAFE) registry is the first prospective study to characterize the incidence, duration, and predictors of atrial high-rate episodes (AHREs) in patients without previous clinically diagnosed atrial fibrillation after dual-chamber pacemaker implantation. Patients underwent in-clinic device interrogation at 2 weeks and then 3, 6, and 12 months after implantation. An AHRE was defined as an atrial tachyarrhythmia with an atrial rate >= 180 beats/min lasting >= 5 minutes. During the first month after pacemaker implantation, AHREs were identified in 68 patients (4.6%). Thirty-four of these patients (50%) did not have AHREs beyond the first month after implantation; these patients were older than those who continued to have AHREs (79 +/- 9 vs 74 +/- 12 years, p = 0.05). Within the first 6 months after pacemaker implantation, 150 patients (10%) experienced a total of 455 AHREs, of which only 28 (6%) prompted clinical visits. The 6-month freedom from an AHRE was 82%. Overall, 75% of patients with AHREs had multiple episodes; most AHREs lasted 5 to 60 minutes. In conclusion, 6 months after dual-chamber pacemaker implantation, 10% of patients experienced 2:1 AHRE, usually lasting 5 to 60 minutes. Some patients had AHREs only within the first 30 days after implantation, suggesting the possibility of transient atrial proarrhythmia related to lead insertion. (C) 2008 Elsevier Inc. All rights reserved.