Personalised pulmonary vein isolation procedure feasible and effective

The Ablate-by-LAW study evaluated a personalised pulmonary vein isolation procedure adapting the ablation index to the left atrial wall thickness. The method was shown to be feasible and effective while posing a less demanding ablation protocol [1].

The main reason for recurrence of paroxysmal atrial fibrillation (AF) is pulmonary vein (PV) reconnection. The left atrium is a thin structure with only 1-5 mm wall thickness and wall thickness is a determinant of transmural lesion formation during AF ablation and an independent predictor for PV reconnection. The utility of the ablation index to dose radiofrequency delivery for the reduction of AF recurrences has already been proven at the posterior and anterior wall. The aim of the presented study was to determine the efficacy, safety, and feasibility of adapting the ablation index to the left atrium wall thickness (LAWT).

In the single-centre Ablate-by-LAW study (NCT04218604), the multi-detector computed tomography-derived LAWT was assessed and integrated into the CARTO navigation system. Left atrial wall thickness maps were computed and categorised into 1 mm-layers and ablation index was titrated to the LAWT (ablation index 300-500 in steps of 50/mm wall thickness). The 3D ‘fingerprinted’ oesophagus images were also computed, the distance between the oesophagus and the left atrial posterior wall was mapped and the lesion personalised by avoiding ablation through the closest part. The primary endpoint was freedom from AF recurrences. Follow-up was scheduled at 1, 3 and 6 months, and every 6 months thereafter.

Dr Cheryl Terés (Teknon Medical Centre, Spain) presented first results from 90 patients included in this study after a follow-up period of 11 months. Mean LAWT was 1.25mm. Mean ablation index was 366on the right PVs with a first-pass isolation in 84 (93%) patients and 380±42 on the left PVs with first-pass in 87 (97%) [1].

Median procedural time was 59 minutes (49-66 min), with 14 minutes (12.5-16 min) radiofrequency time, 0.75 minutes (0.5-1.4 min) fluoroscopy time and 1 mGy/m² fluoroscopy dose area product, thus using a relatively low ablation index compared with previously recorded ablation index protocols. No major complications occurred. First results of the primary endpoint show that, so far, only 4 out of 90 patients (4.5%) had recurrences documented by ECG or self-reported symptoms.

Dr Terés concluded that the feasibility of incorporating 3D LAWT maps was demonstrated and that they can be successfully used for PV isolation. Tailoring of delivered radiofrequency energy and ablation line design depending on wall thickness increased efficacy and showed a high rate of first-pass isolation. Furthermore, recurrence rate was similar to previously reported protocols with lower procedural requirements.

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   1. Teres C. Personalized atrial fibrillation ablation by tailoring ablation index to the left atrial wall thickness. The ablate by-law single center study. EHRA 2021 Congress, 23-25 April.

 

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Posted on 16 June 2021