111 Safety and efficacy of very high-power short duration radiofrequency ablation in a UK cohort using the QDOT micro catheter

Introduction Radiofrequency (RF) is a widely used technology for Atrial Fibrillation (AF) ablation. However, settings for optimal lesion geometry to obtain transmural, durable, and safe lesions are still debated. High Power Short Duration (HPSD) is a novel strategy aiming to create more efficient lesions. We examine the safety and efficacy of the QDOT Micro catheter using its dual abilities, including QMODE+ defined by a very HPSD (90W/4secs) and conventional power temperature controlled QMODE. Methods All patients undergoing Pulmonary Vein Isolation (PVI) using vHPSD for AF at a single UK centre were included in a prospective registry. Patients with additional ablation lines, other than Cavotricuspid Isthmus (CTI), were excluded. Clinical data, procedural details, and data from the most recent follow-up including AF recurrence post 90-day blanking period were recorded. Recurrence was defined as >30 seconds documented AF, either by 12 lead ECG or by Holter-monitor in the event of symptoms. Results A total of 27 patients were treated using vHPSD with the QDOT Micro catheter between January 2023 and January 2024. Patient characteristics are outlined in table 1. At the time of procedure, 41% of patients had a prior electrical cardioversion and 67% were in sinus rhythm. No patients had any accessory pulmonary veins and 22.2% had a common left pulmonary vein ostium. Procedures were carried out using conscious sedation in 37% of cases, and under general anaesthetic in all other cases. A CTI line was performed in 33% of cases for documented atrial flutter. Average procedural time was 163 ± 44 minutes with an average fluoroscopy time of 22.3 ± 14.7 minutes. For all patients, a hybrid approach was undertaken with QMODE+ for the posterior wall and QMODE for the anterior wall. Ablation data is given in table 2. All 4 pulmonary veins were isolated in all cases. First pass isolation (FPI) was 69.2% in the left pulmonary veins (LPVs) and 73.1% in the right pulmonary veins (RPVs). Gap locations for failed FPI are shown in figure 1. Of note, there were 6 (37.5%) gaps in total found on the carina. No gaps were found on the anterior wall of the LPVs. QMODE+ was used for 75% of the LPV touch-ups and 50% of the RPV touch-ups. The safety profile demonstrated 2 (7.4%) pericardial effusions requiring percutaneous drainage and no other complications. Freedom from AF post 6 months was 83.3% among the 18 patients (67%) who had a clinic follow-up in this time. Conclusion The QDOT Micro catheter resulted in good outcomes from ablation with a 100% acute efficacy and 83.3% 6-month efficacy, comparable to conventional RF strategy. Gaps in FPI were most likely found at the carinas. Procedural time, including pre and post ablation care, was under 3 hours. The safety profile was reasonable, but the higher-than-expected rate of pericardial effusion requires further investigation. Expansion of the study with more patients and longer follow-ups is pending. Conflict of Interest No known conflicts