Abstract 12521: Assessing Arrhythmia Burden After Catheter Ablation of Atrial Fibrillation by a Subcutaneous Implantable Loop Recorder: ABACUS Study
Introduction Arrhythmia monitoring in patients (pts) undergoing atrial fibrillation (AF) ablation remains challenging. Holter and trans-telephonic monitors (TTMs) are cumbersome to use and provide limited temporal assessment. Implantable loop recorders (ILRs) may overcome some of these limitations. We conducted a prospective, randomized trial to evaluate utility of an implantable loop recorder (ILR; Reveal XT, Medtronic, Inc) versus conventional monitoring (CM) for assessing arrhythmia burden and pt management post AF ablation.
Methods An ILR with an automatic AF detection algorithm was implanted after ablation in all pts. Pts served as their own controls and AF detection was compared between ILR and CM (2 clinic visits and 30-day auto-trigger TTMs twice) strategies over a 6-month period. AF detection using the ILR algorithm was adjudicated by 3 independent, blinded electrophysiologists.
Results Over 3 months, 44 pts (age 59+10 years; 86% male; paroxysmal AF in 48%; initial ablation in 68%) were enrolled. An ILR was implanted 57+6 minutes after completion of ablation at a mean activated clotting time of 238+45 seconds and INR of 1.9+0.6. In 4 pts ILR was explanted (erosion in 2, cosmetic reasons in 2). Over a mean follow-up of 6±1 months, 28 of the remaining 40 pts (70%) experienced AF (most within 6 weeks after ablation), which was correctly detected by ILR in 27 (96%) and by CM in 16 pts (57%). Pts with AF recurrences detected both by ILR and CM had a higher AF burden than those with AF recurrences detected by ILR only (6.3%±4.1% Vs 1.1%±0.97%, p<0.05). In 8 pts (20%) ILR misclassified sinus rhythm with frequent premature atrial / ventricular complexes as AF. Also, signal under-sensing resulted in ILR rhythm misclassification as asystole or bradycardia in 10 pts (25%). ILR did detect true bradycardia or asystole in 6 pts (15%) which resulted in pacemaker implant in 2 pts and drug modification in 3 pts.
Conclusion ILR can be safely implanted in fully anticoagulated pts following AF ablation procedures and in these pts it can identify arrhythmia recurrences beyond conventional monitoring. However, rhythm misclassification is frequent and requires recognition. With adequate oversight, ILR may serve a useful role in monitoring arrhythmia burden following AF ablation.
- © 2011 by American Heart Association, Inc.