Presence of IAC Delay is Critical to Selecting Patients for IASP

Mary Beth Nierengarten

doi:10.1177/155989771421016

Summary

In patients with intra-atrial conduction delay to the posterior triangle of Koch, pacing the interatrial septum (IAS) may play a role in preventing permanent or persistent atrial fibrillation (AF). This article presents data from the Electrophysiology-Guided Pacing Site Selection study, a prospective, active-controlled, randomized, multicenter study that assessed the efficacy of atrial pacing at the IAS versus the right atrial appendage to prevent persistent or permanent AF in patients with sinus node disease [Verlato R et al. Circ Arrhythm Electrophysiol 2011].

Interventional Techniques & Devices
Cardiology
Arrhythmias
Cardiology Clinical Trials

Interventional Techniques & Devices
Cardiology & Cardiovascular Medicine
Arrhythmias
Cardiology Clinical Trials

In patients with intra-atrial conduction (IAC) delay to the posterior triangle of Koch, pacing the interatrial septum (IAS) may play a role in preventing permanent or persistent atrial fibrillation (AF).

Giovanni L. Botto, MD, S. Anna Hospital, Como, Italy, presented data from the Electrophysiology-Guided Pacing Site Selection study, a prospective, active-controlled, randomized, multicenter study that assessed the efficacy of atrial pacing at the IAS versus the right atrial appendage (RAA) to prevent persistent or permanent AF in patients with sinus node disease (SND) [Verlato R et al. Circ Arrhythm Electrophysiol 2011].

Prior to implantation with an atrial-based pacing device, patients with SND underwent electrophysiologic studies to measure atrial refractoriness and the incremental conduction times from the RAA to the coronary sinus ostium, and the difference (ΔCTos) was calculated. Of the 102 study patients, 3 patients developed permanent AF immediately after device implantation and were excluded from the study.

Of the 99 remaining patients, 66 with IAC delay were assigned to the treatment group (ΔCTos >50 ms) and 33 to the control group (ΔCTos <50 ms). Two patients were lost to follow-up.

The remaining 97 patients in the study were then randomly assigned to either RAA pacing (RAAP) or IAS pacing (IASP) with continuous atrial stimulation within each group. In the treatment group (Figure 1), 29 patients were randomized to IASP and 36 to RAAP. In the control group, 18 were randomly assigned to IASP and 14 to RAAP.

Figure 1.

EPASS Trial Design

AF=atrial fibrillation; ΔCTos=change in conduction time to ostium; IAS=interatrial septum; pts=patients; RAA=right atrial appendage; SND=sinus node disease.Reproduced with permission from Lippincott Williams & Wilkins from Verlato R, Botto GL, Massa R, et al. Efficacy of low interatrial septum and right atrial appendage pacing for prevention of permanent atrial fibrillation in patients with sinus node disease: results from the Electrophysiology-Guided Pacing Site Selection (EPASS) study. Circ Arrhythm Electrophysiol 2011;4:844–850.

Figure 2 provides an example of the left anterior oblique view of the leads positioning in case of low IASP.

Figure 2.

Low IASP: LAO View of Lead Positioning

IASP=interatrial septal pacing; LAO=left anterior oblique.Reproduced with permission from Lippincott Williams & Wilkins from Verlato R, Botto GL, Massa R, et al. Efficacy of low interatrial septum and right atrial appendage pacing for prevention of permanent atrial fibrillation in patients with sinus node disease: results from the Electrophysiology-Guided Pacing Site Selection (EPASS) study. Circ Arrhythm Electrophysiol 2011;4:844–850.

Table 1 shows the electrophysiologic baseline parameters of the study patients. The patients were assessed every 6 months. The primary end point was time to development of permanent or persistent AF in the 2-year study.

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Table 1.

Baseline Parameters of Patients in EPASS

The results of the study showed that 11 patients (16.6%) in the treatment group developed permanent or persistent AF. Of these, 2 patients had IASP and 9 had RAAP (Figure 2) [Verlato R et al. Circ Arrhythm Electrophysiol 2011]. In the control group, 4 patients developed permanent or persistent AF, 2 with IASP and 2 with RAAP. More patients in the treatment group maintained sinus rhythm with IASP than with RAPP (p=0.047).

Prof. Botto stated that the study showed the superiority of low IASP over RAAP in preventing persistent or permanent AF in patients with sinus node disease and IAC delay to the posterior triangle of Koch.

The study also highlighted the importance of IAC delay in selecting patients who benefit from IASP, on the basis of the finding of no significant difference between low IASP and RAAP in the absence of IAC delay in the control group. Prof. Botto noted that these patients can easily be identified by a quick electrophysiologic study during device implantation. The algorithms for continuous atrial pacing and the lead technology to permanently pace specific atrial sites are available.

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