Abstract 2166: Incidence and Significance Of Newly Detected Atrial High Rate Episodes In Patients With Implantable Cardioverter-defibrillators
Introduction: Pts with ICDs who have a prior history of AF are at increased risk of receiving appropriate and inappropriate shocks. The clinical significance of atrial high rate events (AHREs) in ICD pts without prior history of AF is unknown. We sought to determine the incidence of newly detected AHREs ≥ 5 min duration and the predictors of appropriate and inappropriate therapies in ICD pts without prior history of AF.
Methods and Results: We evaluated 228 pts (173 male; mean age 65 ± 13) without prior history of AF who underwent dual chamber and biventricular ICD implantation in 2005 and 2006. Pt demographics, co-morbidities, medications, and device parameters were recorded. The frequency, duration and time to first AHRE ≥ 5 min as well as the frequency and time to first appropriate and inappropriate ICD shocks were determined. During follow-up of 583 ± 248 days, AHREs ≥ 5 min were seen in 44 (19%) pts. Of these, 8 (18%) had AHREs ≥ 24 hs duration. Pts with AHREs ≥ 5 min were more likely to have appropriate ICD therapies (39% vs. 18%; p = 0.003), appropriate ICD shocks (14% vs. 3%; p = 0.006), and inappropriate shocks (16% vs. 2%; p < 0.001) when compared to patients without AHREs. Baseline age, gender, etiology of cardiomyopathy, serum creatinine, ejection fraction and medication use were not found to be significant predictors of appropriate ICD therapies, shocks or inappropriate shocks.
Conclusions: Newly detected AHREs ≥ 5 min were strongly associated with both appropriate and inappropriate shocks in ICD pts without previously documented AF. This was seen even when the majority (>80%) of pts had only brief AHREs (< 24 hs duration).