Use of entrainment and overpacing of atrial tachyarrhythmias through CIED in outpatient clinic setting in locating site and termination of AT. Our experience of feasibility and reliability

Atrial tachyarrhythmias (AT) are common in patients with cardiac implantable electronic devices (CIED). CIED may be used in an outpatient clinic setting to entrain and overpace ATs. Entrainment may provide important information for further clinical decision making.

The aims of the present study were (1) to analyze the feasibility and success rate of entrainment and overpacing maneuvers in a real-world outpatient clinic setting; (2) to assess the correlation between entrainment’s findings, ECG and catheter ablation results.

We enrolled patients with CIED and AT in whom entrainment was attempted at the outpatient clinic. According to a routine clinical protocol, the use of anticoagulation was confirmed and a 12-lead ECG was collected. One electrophysiologist independently assessed whether the AT morphology based on surface ECG was consistent with typical CTI-dependent atrial flutter. Entrainment (pacing from atrial lead 30 ms faster than tachycardia cycle length),was performed and preferably repeated to prove reproducibility . Post pacing interval (PPI) was considered suggestive for a right-sided AT when ≤100 ms above tachycardia cycle length (TCL +), while suggestive for left-sided AT when >100 ms TCL+. If AT was unchanged by entrainment, overpacing maneuver was attempted in order to interrupt the arrhythmia. When clinically indicated, catheter ablation was scheduled (Fig.1).

Entrainment was attempted in 67 patients (mean age 69±10, 84% males, 12-leads ECGs collected in 58 (87%). The entrainment maneuver was successful in 61 patients (91%, Fig. 2 panels A-B) and failed in 4 patients (6%, Fig. 2 panel C). Overpacing was attempted in 57 patients (85%) resulting in conversion to sinus or paced rhythm in 39% (22 of 57). In 61% (35 of 57) overpacing resulted in unchanged AT, acceleration of AT’s CL or atrial fibrillation. During follow-up a total of 23 patients (34%) underwent AT ablation 5±7 months after entrainment. In this cohort, 6 of 23 patients showed only left-sided AT(s), 15 of 23 showed right-sided AT (13/15 CTI-dependent flutter) and 2 patients had both left- and right-sided ATs. Entrainment with a PPI ≤100 ms had positive predictive value (PPV) of 94% (16 of 17) and a negative predictive value (NPV) of 100% (4 of 4) in predicting the presence of right-sided ATs, while adopting a PPI ≤50 ms the PPV was 100% (12 of 12), with a NPV of 55% (5 of 9). A surface ECG was available in 20 of 23 patients who underwent AT ablation. In all of 9 patients with ECG consistent with typical CTI flutter, the PPI was ≤100 ms and during ablation a CTI dependent flutter was identified and successfully ablated.

Entrainment of AT through CIEDs is feasible and highly accurate to identify right-sided ATs, in outpatient clinic settings, which may facilitate procedural planning for catheter ablation. Overpacing of AT from CIEDs was moderately effective in terminating AT.