Analysis of mitral isthmus ablation in patients undergoing a second ablation procedure after atrial fibrillation ablation with electroporation vs. radiofrequency

Pulmonary vein isolation is the best option in most cases for the treatment of atrial fibrillation (AF) due to its clinical and prognostic results. Pulse Field Ablation (PFA) ablation is a proven method with results comparable and even superior in some respects to other energy sources. There are scenarios in which its advantages have not yet been validated by clinical trials, such as in the approach to left flutter, where ablation of substrates other than the pulmonary veins, such as the mitral isthmus (MI), is required. Achieving lateral MI block is technically complex and requires prolonged radiofrequency ablations and often a coronary sinus approach or alcohol ablation of the Marshall vein.

The aim is to analyze the initial experience of our center in terms of intraprocedural success, efficacy and safety of PFA in MI ablation in patients with AF and perimitral flutter, compared to radiofrequency.

We present a retrospective descriptive study with a consecutive sample of 55 patients ablated for previous AF who underwent a new AF ablation procedure and/or atypical flutter in which mitral isthmus ablation was performed, in them18 by electroporation and in 37 by radiofrequency. The cases were collected from July 2023 to July 2024. We analyzed the baseline characteristics of the patients, the success of the procedure, complication rate, and efficacy at 1 year.

Both groups were comparable, with baseline characteristics without significant differences (except for more dyslipidemia in the radiofrequency group). In the group of patients ablated with electroporation, there was a tendency for a higher percentage of patients with persistent arrhythmia (70.5% vs 54.1%). There was a single complication in the radiofrequency group, mitral isthmus block was observed in 94% of cases in both groups, and the electroporation group showed a tendency to have fewer reconnected pulmonary veins (33% vs 56%). The percentage of patients who presented arrhythmic recurrence in the first year was 40.5% in the radiofrequency group vs 23% in the electroporation group, with a p-value of 0.056.

In our initial experience, electroporation is a safe, simple and effective method for acutely achieving endocardial MI blockade, which is why we consider it comparable to radiofrequency and even advantageous in some scenarios.