Focus issue: Atrial fibrillation: ClinicalDeviceTemporal relationship of atrial tachyarrhythmias, cerebrovascular events, and systemic emboli based on stored device data: A subgroup analysis of TRENDS
Introduction
It is well recognized that atrial fibrillation (AF) promotes thrombus formation in the left atrium and that these thrombi may embolize.1, 2, 3, 4 The rate of ischemic stroke associated with nonvalvular AF averages 5% per year, a rate that is two to seven times that of the general population. However, many risk factors for AF (elderly age, heart failure, hypertension, diabetes mellitus, atherosclerotic disease) are also independent risk factors for ischemic stroke that is not cardioembolic.4, 5 The purpose of this study was to determine the temporal relationship of AF, as detected by implantable cardiac devices, relative to the onset of symptoms of cerebrovascular events/systemic emboli (CVE/SE) in patients with and those without AF.
Section snippets
Study population
The study population consists of the subgroup of 40 patients enrolled in the TRENDS study who experienced CVE/SE and for whom 30 days monitoring prior to CVE/SE was available. In brief, TRENDS was a prospective, observational study that enrolled 2,486 patients with an indication for a pacemaker or a cardioverter-defibrillator and at least one stroke risk factor of heart failure, hypertension, age ≥65 years, diabetes, or prior stroke/transient ischemic attack (TIA).6, 7 Physicians were
Detection of AT/AF prior to CVE/SE
Among the 40 patients who experienced CVE/SE, AT/AF was detected, at any time, prior to CVE/SE in 20 patients and was not detected prior to CVE/SE in the remaining 20 patients. Other than the average and maximum daily AT/AF burden and the duration of device monitoring prior to CVE/SE, no statistically significant differences were seen between patients with and those without AT/AF prior to CVE/SE (Table 1). However, because of the small number of patients in this study, the power of this
Main findings
The purpose of the present subgroup analysis of the TRENDS study was to assess the temporal relationship between CVE/SE and atrial tachyarrhythmias in a device population both with and without AT/AF. The two main conclusions of the TRENDS study were that (1) the annualized CVE/SE rate was remarkably low (1.2%) and (2) an AT/AF burden ≥5.5 hours in any 30-day period doubled CVE/SE risk.7 However, in the current study, patient-specific analysis revealed that only 50% of patients who experienced
Conclusion
The incidental finding of AF events recorded by an implanted device is common and poses a clinical challenge because the practical significance is unknown. When considering warfarin therapy, many physicians rely on information on recent AF episodes to impact their decision. This approach may explain, in part, the underutilization of anticoagulation despite its proven benefit28, 29 and the discontinuation of anticoagulation in patients at high risk for stroke who seem to be maintaining sinus
Acknowledgments
Drs. Philip A. Wolf, David Anderson, and José Biller were the neurologists who adjudicated the outcome events.
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Cited by (0)
The TRENDS study was sponsored by Medtronic, Inc. (Minneapolis, MN, USA). Christopher Hilker, Jodi Koehler, and Paul D. Ziegler are employees and stockholders of Medtronic, Inc. Drs. Daoud, Glotzer, Wyse, and Ezekowitz served as consultants for Medtronic, Inc.