INTRODUCTION: Pacemaker (PPM)-detected atrial high-rate episodes (AHREs) of even 5-minute duration may identify patients at increased risk for stroke and death. In this study, we sought to determine the incidence of newly detected atrial fibrillation (AF defined as an AHRE > or = 5 minutes) in patients following dual-chamber PPM implantation and to define the clinical predictors of developing AF. METHODS AND RESULTS: We evaluated 262 patients (142 male; age 74 +/- 12 years) without documented AF who underwent PPM implantation for sinus node dysfunction (n = 122) or atrioventricular block (n = 140). Information regarding patient demographics, cardiovascular diseases, and medication history was obtained. The cumulative percentages of ventricular pacing as well as the frequency, duration, and time to first episode of an AHRE were also determined. During follow-up of 596 +/- 344 days, an AHRE > or = 5 minutes was detected in 77 (29%) patients. Of these, 47 (61%) patients had an AHRE > or = 1 hour, 22 (29%) patients had an AHRE > or = 1 day, and 12 (16%) patients had an AHRE > or = 1 week. An AHRE > or = 5 minutes was seen in 24% and 34% of patients at 1 year and 2 years, respectively. Among patients with sinus node dysfunction, > or = 50% cumulative ventricular pacing was the only significant predictor of an AHRE > or = 5 minutes (HR 2.2; CI 1.0-4.7; P = 0.04). CONCLUSIONS: Within 1 year of PPM implantation, AF is detected in 24% of patients without history of AF. In patients with sinus node dysfunction, > or = 50% cumulative right ventricular pacing is associated with a 2-fold increase in risk of developing AF.
