Elsevier

Heart Rhythm

Volume 9, Issue 8, August 2012, Pages 1241-1246
Heart Rhythm

Clinical
Devices
Positive predictive value of device-detected atrial high-rate episodes at different rates and durations: An analysis from ASSERT

https://doi.org/10.1016/j.hrthm.2012.03.017Get rights and content

Background

Pacemakers can automatically identify and catalog atrial high-rate episodes (AHREs). While most AHREs represent true atrial tachyarrhythmia/atrial fibrillation (AT/AF), a review of stored electrograms suggests that a substantial proportion do not. As AHREs may lead to the initiation of oral anticoagulation, it is crucial to understand the relationship between AHREs and true AT/AF.

Objective

To compare the positive predictive value of AHREs for electrogram-confirmed AT/AF for various atrial rates and episode durations.

Methods

By using data from 2580 patients who participated in the ASymptomatic atrial fibrillation and Stroke Evaluation in pacemaker patients and the AF Reduction atrial pacing Trial, all AHREs >6 minutes and >190 beats/min with available electrograms were reviewed to determine whether they represented true AT/AF. The positive predictive value of these AHREs was assessed for episode durations of 6 minutes, 30 minutes, 6 hours, and 24 hours at atrial rates of 190 and 250 beats/min.

Results

Of 5769 AHREs >6 minutes and >190 beats/min, 82.7% were true AT/AF and 17.3% were false positives (predominantly due to repetitive non–re-entrant ventriculoatrial synchrony). False positives dropped to 6.8%, 3.3%, and 1.8% when the threshold duration was increased to 30 minutes, 6 hours, and 24 hours, respectively. Increasing the threshold heart rate to 250 beats/min added little to the positive predictive value when longer threshold durations were used.

Conclusions

By using a cutoff of >6 minutes and >190 beats/min, the rate of false-positive AHREs is 17.3%, making physician review of electrograms essential. For AHREs lasting >6 hours, the rate of false positives is 3.3%, making physician review less crucial.

Introduction

Modern pacemakers and implantable cardioverter-defibrillators (ICDs) can be programmed to record atrial high-rate episodes (AHREs), with the goal of documenting episodes of atrial fibrillation (AF) and other atrial tachyarrhythmia (AT).1, 2, 3 In patients with hypertension, heart failure, diabetes, stroke, or advanced age, clinically detected AT/AF is associated with a substantial increase in the risk of stroke4, 5 and chronic anticoagulation often is advised.6 The recently published ASymptomatic atrial fibrillation and Stroke Evaluation in pacemaker patients and the AF Reduction atrial pacing Trial (ASSERT) demonstrated that subclinical AT/AF, detected only by a pacemaker or an ICD, was associated with a 2.5-fold increased risk of stroke3 and that this risk approached 4% per year among patients with a CHADS2 score of 2 or more. Although it is yet to be demonstrated that the treatment of pacemaker-detected AT/AF reduces stroke in this population, physicians must frequently decide whether anticoagulation is indicated in pacemaker patients with AHREs. Because anticoagulation is associated with an important risk of bleeding, physicians must be confident that AHREs that are detected represent true AT/AF. Because stored electrograms are not always available, it would be important for physicians to know the positive predictive value of AHREs for different rates and durations of arrhythmia.

Section snippets

Methods

The design and main results of ASSERT have previously been published.3, 7 The study included 2580 patients 65 years or older with a history of hypertension who had a first-time St Jude Medical dual-chamber pacemaker or ICD implanted within 8 weeks. Patients were excluded if they had a history of AF or atrial flutter lasting more than 5 minutes or if they required anticoagulation with a vitamin K antagonist for any indication.7

All patients had bipolar atrial leads with the sensitivity programmed

Results

A total of 17,124 unique AHREs with electrograms were adjudicated, of which 5769 were >6 minutes and >190 beats/min, the predefined threshold for “significant” AHREs in ASSERT. Of these, 82.7% were appropriate detections while 17.3% were inappropriate detections (13.9% RNRVAS, 1.3% sensing of farfield R wave, 1.2% noise, and 0.9% other), as shown in Figure 1. Of the adjudicated AHREs that were <6 minutes in duration, only 48% were true AT/AF and most of the inappropriate detections were due to

Discussion

The primary finding of this study is that although AHREs lasting more than 6 minutes are likely to be true AT/AF, the positive predictive value is only 82.7%. However, for AHREs lasting more than 6 hours, the positive predictive value is 96.7%, which is comparable to the interobserver agreement (96.5%) during blinded adjudication. Thus, for AHREs lasting more than 6 hours, physician review of stored electrograms is unlikely to improve diagnostic accuracy. On the other hand, physician review of

Conclusions

Automatic detection of AHREs by pacemakers and ICDs can provide early detection of asymptomatic AT/AF. Using the studied St Jude Medical devices and a cutoff of >6 minutes and >190 beats/min, the rate of false-positive AHREs is 17%, making physician review of electrograms necessary. For AHREs lasting >6 hours, the rate of false positives is <3%, making physician review less crucial. AHRE detections are associated with a substantial increase in the risk of nonhemorrhagic stroke.

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This study was supported by a grant from St Jude Medical. In addition, Dr Brandes received grant support from Biotronik, Boehinger-Inelheim, Medtronic, MSD, Sanofi-Aventis, and St Jude Medical as well as consulting fees/honoraria from Biotronik, Boehringer-Ingelheim, Bristol-Myers Squibb, Medtronic, MSD, Sanofi-Aventis, and St Jude Medical. Dr Healey received research grant support from St Jude Medical, Boston Scientific, Astra-Zeneca, and Boehringer-Ingelheim as well as consulting fees from Boehringer-Ingelheim and Bayer.

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ASSERT Steering Committee members: Jeff S. Healey, Stefan H. Hohnloser, Stuart J. Connolly, Michael R. Gold, Carsten W. Israel, Isabelle C. Van Gelder, Alessandro Capucci, C.P. Lau, Eric Fain, Sean Yang, Christophe Bailleul, Carlos A. Morillo, Mark Carlson, and Ellison Themeles.

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