# Evaluation of Intercaval Bundle Connection by Multisite Pacing and Right-Sided Pulmonary Vein Isolation

## TL;DR

This study shows that multisite pacing can better detect an intercaval bundle connection, which affects the success of pulmonary vein isolation in heart procedures.

## Contribution

The study introduces a novel method using multisite pacing to identify intercaval bundle connections and their impact on ablation outcomes.

## Key findings

- Multisite pacing detected intercaval bundle connections in all 108 patients, compared to only 20.4% with standard RA pacing.
- The location of earliest activation sites influenced the need for additional ablation in the right anterior PV carina.
- The distance from the earliest activation site to the PV ostium varied significantly across different groups.

## Abstract

An intercaval bundle connection (IBC) between the right pulmonary vein (PV) and the right atrium (RA) reduces PV isolation success, but the epidemiology requires elucidation.

The authors investigated the frequency and distribution of IBC diagnosed by multisite pacing and its relation to PV isolation outcomes.

We analyzed 108 patients who underwent first PV isolation under radiofrequency ablation. An activation map was created by multisite pacing from the RA, the right inferior PV, and the earliest activation site of RA (EAS-RA) via right inferior PV pacing.

Compared with RA pacing, multisite pacing more frequently delineated IBC (100% [108/108] vs 20.4% [22/108]; P < 0.001). The EAS-RA was classified as “above” (n = 19), “below” (n = 79), and “far below” (n = 10) in relation to the right inferior PV. The earliest activation site of the left atrium (EAS-LA) obtained by EAS-RA pacing was classified as “PV inside” (n = 11), “PV side” (n = 15), and “LA side” (n = 81) in relation to the PV isolation line. The median distances from the EAS-LA to the PV ostium in the “above,” “below,” and “far below” groups were significantly different (3.4 [IQR: −2.1 to 7.2] mm vs 7.7 [IQR: 6.8-13.5] mm vs 15.2 [IQR: 13.4-20.7] mm; P < 0.001). Notably, “above” EAS-RA was related to “PV inside” EAS-LA. Additional ablation for the anterior carina was more common in “PV inside” than “PV side” and “LA side” (75.0% [9/12], 46.7% [7/15] and 6.2% [5/81]; P < 0.001).

The IBC was visualized in all cases by multisite pacing. An attachment site on the LA side influenced the frequency of additional ablation for the right anterior PV carina.