Wall thickness‐based adjustment of ablation index improves efficacy of pulmonary vein isolation in atrial fibrillation: Real‐time assessment by intracardiac echocardiography

Abstract

Background Ablation index (AI) linearly correlates with lesion depth and may yield better therapeutic performance in pulmonary vein isolation (PVI) when tailored to a patient's wall thickness (WT) in the left atrium (LA). Methods and results First study: In paroxysmal atrial fibrillation patients (PAF; n = 20), the average LA WT (mm) in each anatomical segment for PVI was measured by intracardiac echocardiography (ICE) placed in the LA; the optimal AI for creating 1‐mm transmural lesion (AI/mm) was calculated. Second study: PAF (n = 80) patients were randomly assigned either to a force‐time integral protocol (FTI; 400 g·s, n = 40) or a tailored‐AI protocol (TAI; n = 40). In TAI, the LA WT in each segment was individually measured by ICE before starting ablation; a target AI was adjusted according to the individual WT in each segment (AI/mm × WT). The acute procedure outcomes and the 1‐year AF‐recurrence rate were compared between FTI and TAI. TAI had higher success rate of first‐pass isolation (88% vs. 65%) and had lower incidence of residual PV‐potentials/conduction‐gaps after a circular ablation than FTI (15% vs. 45%). The procedure time to complete PVI decreased in TAI compared to FTI (52 vs. 83 min), being attributed to the increased radiofrequency power and the decreased radiofrequency application time in each point in TAI. TAI had a lower 1‐year AF‐recurrence rate than FTI. Conclusion TAI increased acute procedure success, decreased time for PVI, and reduced the 1‐year AF‐recurrence rate, compared to FTI. Understanding the precise ablation target and tailoring AI would improve the efficacy of PVI.

Real-time visualization of the esophagus and left atrial posterior wall by intra-left atrial echocardiography

“…CartoSoundstar Ⓡ can provide to visualize the detailed cardiac structure and other structures of interest including the esophagus when introduced directly into the LA cavity. Recently, Motoike et al reported that ICE introduced directly into the LA could evaluate wall thickness in the area surrounding the PV [10]. They concluded that wall thickness based on ICE AI-tailored approach increased the success rate of first-pass isolation compared to the force-time integral (FTI)-based approach.…”

“…This method seemed to allow us to create the 3D esophagus image adjacent to the LAPW in a real-time fashion during the AF ablation procedure and assess the direct relationship between the esophagus and LAPW. A recent report by Motoike et al reported the usefulness of ICE introduced into the LA in measuring the LA wall thickness [10], but there are no reports which assessed the esophagus and details of the adjacent LAPW thickness by ICE inserted into the LA. The purpose of the study was to validate the present method of esophagus visualization and analyze the LAPW thickness adjacent to the esophagus.…”

INtra-procedural ultraSound Imaging for DEtermination of atrial wall thickness and acute tissue changes after isolation of the pulmonary veins with radiofrequency, cryoballoon or laser balloon energy: the INSIDE PVs study

“…The different morphological changes produced by the different ablation energies could suggest different mechanisms of lesion failure. Recent data suggest that the adjustment of the ablation settings based on baseline LA wall thickness can improve the procedure outcome and reduce the risk of collateral injury 12 . A further adjustment based on the acute wall thickening produced by energy delivery for ablation could also be bene cial when using RF or laser energy and could potentially highlight gaps between lesions.…”

“…Ultrasound imaging has previously beenused in animal studies for assessment of atrial wall thickness and lesion formation during catheter ablation [8][9][10] . Preliminary data in human also suggest that ultrasound imaging modalities such asintracardiac echocardiography (ICE) and intravascular ultrasound (IVUS) can be used for left atrial (LA) wall thickness measurements and detection of acute changes produced by ablation [11][12][13] . This pilot study was conducted to compare ICE and IVUS for real-time LA wall imaging and assessment of acute tissue changes produced by different ablation energies during pulmonary vein isolation (PVI).…”

Mirror mirror on the wall: Which is the best ablation index of all?

“…This has a potential impact on outcomes of AI guided ablation [ 16 ]. An attempt has been made to tailor AI to the left atrial wall being targeted with the help of intracardiac echocardiography (ICE) but this increases procedure costs and complexity [ 17 ]. Also important is the underlying tissue health and presence of scarring.…”