AIMS: Cavotricuspid isthmus (CTI) ablation is commonly performed alongside catheter ablation of atrial fibrillation (AF). However, the acute efficacy of the CTI ablation using the pentaspline catheter and pulsed electric field (PEF) energy has not been systematically evaluated. This randomized study assessed the acute efficacy and extent of haemolysis associated with CTI ablation when performed using two different configurations of the pentaspline catheter. METHODS AND RESULTS: A total of 178 patients (age 65 ± 10 years, 66% of males) undergoing PEF ablation of the CTI in conjunction with AF ablation were randomly assigned to receive ablation using either the basket configuration (n = 95) or the flower configuration (n = 83) of the pentaspline catheter. The CTI ablation was performed before left atrial ablation. It was guided by intracardiac echocardiography, and bidirectional block was confirmed by pacing manoeuvres. Venous blood samples to assess haemolytic biomarkers were collected before and immediately after the CTI ablation. The groups were broadly comparable in baseline characteristics. The flower group demonstrated superior procedural efficiency, with fewer applications required to achieve a CTI block (3.4 ± 3.1 vs. 8.0 ± 4.1, P < 0.001), a shorter time to block (96 ± 289 vs. 177 ± 192 s, P < 0.001), and fewer total applications (10.1 ± 3.4 vs. 13.3 ± 5.1, P < 0.001). Acute reconduction occurred in 20% of cases overall, but was significantly lower in the flower group (6% vs. 32%, P < 0.001; hazard ratio: 0.14, 95% confidence interval: 0.06-0.40). Haemolysis was notably lower in the flower group, with significantly less post-procedural free haemoglobin (154 ± 112 vs. 210 ± 115 mg/L, P < 0.001). One case of transient ST elevations occurred in the flower group without clinical consequence. CONCLUSION: Pulsed electric field ablation of the CTI using the flower configuration of the pentaspline catheter demonstrated higher acute efficacy in achieving CTI block and a more favourable safety profile regarding haemolysis compared to the basket configuration. This is likely due to the larger footprint and improved tissue contact of all electrodes, minimizing the leakage of PEF energy into the blood pool.

2nd Department of Medicine Department of Cardiovascular Medicine 1st Faculty of Medicine Charles University General University Hospital Prague Prague Czechia

2nd Faculty of Medicine Charles University Prague Czechia

Department of Cardiology České Budějovice Hospital and University of South Bohemia České Budějovice Czechia

Department of Cardiology Institute for Clinical and Experimental Medicine Vídeňská 1958 9 Prague 140 21 Czechia

Department of Clinical Sciences and Community Health Cardiovascular Section University of Milan Milan Italy

Department of Internal Medicine and Cardiology University of Ostrava Ostrava Czechia

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