PV isolation has been considered the cornerstone of catheter ablation for the treatment of patients with AF. However, non-PV triggers can be identified in 10% to 33% of unselected patients with AF. One of such triggers the IVC has recently been explored as a target for ablation in a study by Nie et al. The authors found that IVC trigger is a rare but latent source of paroxysmal AF, could be identified and safely eliminated by focal radiofrequency ablation.

This study was performed to investigate the incidence, characteristics, and implications of IVC triggers for AF.
A total of 661 patients who underwent initial paroxysmal AF ablation were included. After pulmonary vein isolation, ectopic beats that triggered AF were further studied. Activation mapping and angiography were performed to confirm the location of ectopic origin. Electrocardiographic analysis of the ectopic P wave (P′ wave) was performed.
The authors found that:

1. Six patients (0.91%) had AF triggered by the IVC were confirmed.
2. The mean distance from the earliest activation site to the IVC ostium was 6.8 ± 2.5 mm.
3. Furthermore, the arrhythmogenic foci within the IVC were all located at the apical hemisphere of the IVC.
4. A total of 2.3 ± 0.5 applications of radiofrequency energy were delivered to eliminate IVC triggers.
5. The mean duration of the P′ wave was narrower than that of the sinus P wave.
6. Moreover, the configuration of all P′ waves in the inferior leads was negative.
7. During a mean follow-up period of 25.5 ± 7.3 months, all 6 patients remained arrhythmia free without antiarrhythmic drugs.
The focal application of radiofrequency energy in the IVC is a highly effective and safe approach to eliminate IVC triggers.
In patients with paroxysmal AF, non-PV triggers should be appropriately identified and eliminated after PV isolation. Although with a rare incidence, the IVC can serve as a latent trigger for paroxysmal AF. The P′ wave configuration could be the first trace for identifying the triggers. Under the guidance of elaborate activation mapping and other methods, it would be easy to confirm and eliminate the origin sites of non-PV triggers.
Further studies are needed to evaluate and develop a practical approach for recognizing AF triggers from the IVC and other locations.
Source: JACC CE: J Am Coll Cardiol EP. Jul 27, 2022. Epublished DOI: 10.1016/j.jacep.2022.05.007