Noninvasive pacing study via pacemakers and implantable cardioverter-defibrillators for differentiating right from left atrial flutter.

Background: Patients with atrial flutter who are implanted with a pacemaker (PM) or implantable cardioverter-defibrillator (ICD) present with the opportunity to perform a noninvasive pacing study (NIPS) using the right atrial pacing lead to differentiate right from left atrial flutter.
Objectives: The purpose of this study was to study the feasibility and accuracy of NIPS to distinguish right from left atrial flutter.
Methods: We enrolled consecutive patients scheduled for an electrophysiological study or ablation procedure who were in atrial flutter and who were implanted with a PM or ICD with a functional atrial lead in the right atrial appendage. Flutter tachycardia cycle lengths (TCLs) and postpacing intervals (PPIs) were measured noninvasively via the device during the procedure.
Results: A total of 48 (67%) patients were studied. Right atrial flutter was present in 32 patients (of whom 29 had typical cavotricuspid isthmus-dependent flutter) and 16 (33%) patients had left atrial flutter. A PPI-TCL interval of >100 ms was 100% specific and 81% sensitive to identify left atrial flutter, with an overall accuracy of 94% and a c statistic of 0.94 (95% confidence interval 0.87-1.00). A PPI-TCL interval of ≤100 ms had a positive predictive value of 86% for diagnosing typical flutter.
Conclusion: NIPS via PMs and ICDs with a PPI-TCL interval of >100 ms can reliably identify left atrial flutter (although we have only validated this cutoff for leads implanted in the right atrial appendage). This simple maneuver may allow planning for left-sided access and may avoid an unnecessary invasive electrophysiological study if left atrial flutter ablation is not to be considered.
(Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)