Recent studies have indicated that brief periods of atrial fibrillation (AF) detected by implantable pacemakers are associated with an increased risk of ischemic stroke. However, effective clinical utilization of diagnostic data provided by these devices is predicated upon high accuracy of the automatic AF detection algorithms. Furthermore, excessive false positive detections can be burdensome and frustrating for clinicians to review.
All AF episodes with stored electrograms (EGM) from the randomized phase of the RESPECT study (Medtronic AT500 or EnRhythm™ pacemakers) were manually adjudicated. We tabulated the positive predictive value (PPV) and 95% confidence intervals for AF detection as a function of episode duration (≤ 6 minutes, > 6 minutes, > 30 minutes, > 6 hours, and > 24 hours) and APP status (on/off).
Device-based detection of AF has a very high PPV across all episode durations and is unaffected by the APP algorithm. The findings suggest that AF diagnostics from these Medtronic pacemakers can be utilized without intensive manual adjudication of individual episodes.
AF detection accuracy rates determined from independent clinical trials are presented for reference.
PR Logic™ uses pattern and rate analysis to discriminate between supraventricular tachycardia (SVT) and true ventricular tachyarrhythmias. It can withhold inappropriate VT/VF detection and therapy during episodes of rapidly conducted SVT in dual chamber devices.
A controlled head-to-head study evaluating the comparative performance of device algorithms has not been done.
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Ziegler, P. Calculation of Positive Predictive Value for AT/AF Detection from the Assert Trial. Medtronic data on file. January 2013.