The Relationship between Daily Atrial Tachyarrhythmia Burden from Implantable Device Diagnostics and Stroke Risk: The TRENDS Study
Background—It is unknown if brief episodes of device-detected atrial fibrillation (AF) increase thromboembolic event (TE) risk.
Methods and Results—TRENDS was a prospective, observational study enrolling patients with ≥1 stroke risk factor (heart failure, hypertension, age≥65, diabetes, or prior TE) receiving pacemakers or defibrillators that monitor atrial tachycardia (AT)/AF burden (defined as the longest total AT/AF duration on any given day during the prior 30-day period). This time-varying exposure was updated daily during follow-up and related to TE risk. Annualized TE rates were determined according to AT/AF burden subsets: zero, low (<5.5 hours [median duration of subsets with non-zero burden]), and high (≥5.5 hours). A multivariate Cox model provided hazard ratios including terms for stroke risk factors and time-varying AT/AF burden and antithrombotic therapy. 2486 patients had at least 30 days of device data for analysis. During a mean follow-up of 1.4 years, annualized TE risk (including TIA's) was 1.1% for zero, 1.1% for low, and 2.4% for high burden subsets of 30-day windows. Compared to zero burden, adjusted hazard ratios (95% confidence interval) in the low and high burden subsets were 0.98 (0.34-2.82, p=0.97) and 2.20 (0.96-5.05, p=0.06), respectively.
Conclusions—The TE rate was low compared to traditional AF patients with similar risk profiles. The data suggest that TE risk is a quantitative function of AT/AF burden. AT/AF burden ≥5.5 hours on any of 30 prior days appeared to double TE risk. Additional studies are needed to more precisely investigate the relationship between stroke risk and AT/AF burden.
- Received January 20, 2009.
- Accepted July 27, 2009.
- Copyright © 2009, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited