Introduction: Atrial Fibrillation (AF) is the most common cardiac arrythmia in adults worldwide. Catheter ablation (CA) is accepted as a safe and effective therapy for AF and left atrial tachycardias (AT) and is well-established standard of care. However, the procedure can lead to life-threatening complications, including thromboembolic cerebrovascular events (CVE). Transesophageal echocardiography (TOE) is the gold standard for screening for left atrial appendage thrombus (LAAT) and is performed in many cases prior to CA of AF. However, concerns have been raised regarding intrinsic risks of TOE, cost effectiveness, increase in procedural duration time, and the growing burden, placed on echocardiography laboratories, as the volume of procedures increases worldwide. The guidelines are limited on the precise role of LA imaging for thrombus prior to CA.

Purpose: The aim of our retrospective analysis was to evaluate the safety of individualized TOE approach for patient undergoing CA of AF or left atrial AT in the two participating centers.

Methods: Patients, undergone AF or left atrial AT ablation between August 2018 and October 2022 at two centers were enrolled in this study. Patients were scheduled to TOE when one of the following criteria was met: 1) prior history of either thromboembolic stroke or 2) LAAT, 3) inappropriate anticoagulation (OAK) regimen in 4 weeks prior to CA. Otherwise, no TOE prior to CA was performed. (Figure 1). During the CA procedure careful standard anticoagulation management was performed including Heparin infusion with ACT goal between 300- 350 s, transseptal introducer and catheter irrigation with heparinized solution. TOE and CA outcomes were retrospectively analyzed. CVE incidence from the procedure onset to 24 hours post-procedure was evaluated.

Results: A total of 1156 Patients were analyzed. The median age of study population was 70 (IQR: 62-76) years. 675 patients (58.4%) were male, 555(48.1%) had a persistent AF/AT and 358 (31%) had already left atrial CA in prior history. The CHA2DS2-VASc score was ≥ 2 in 939 (81.2%) patients. 505 patients (43.7%) were on apixaban, 359(31.0%) on rivaroxaban, 22(1,9%) on dabigatran, 103(8.9%) on edoxaban, 94(8.13%) on VKA, 73(6.3%) had no OAK prior to ablation (6 patients due to previous LAA occluder implantation, in 1 patient due to LAA resection). The median left ventricular ejection fraction was 59% (IQR: 50-60%), median left atrial volume index was 43.6 (IQR: 28.8-55) ml/m².TOE was performed in 261(22.6%) of patients, in 93 due to stroke history, in 24 due to LAAT history, in 161 due to inappropriate OAK. No LAA Thrombi were detected. Total 4 out of 1156 (0.35%) experienced CVE (Table 1). In 2 of these cases TOE was performed prior to CA, and LAA thrombi were ruled out. In another 2 patients in heart computer tomography immediately after stroke LAAT were excluded. Even not statistically significant, the higher rate of the CVE among the patients with TOE performed (2 out of 261 patients, 0.76%) emphasizes the higher baseline risk of thromboembolic events in this category of patients as opposed to the patients with low stroke risk where TOE was omitted (2 out of 895 patients, 0.22%, p=0.22).

Conclusions: Individualized selective approach to TOE prior to CA of AF or left AT showed to be safe. The stroke incidence (0.35%) in this approach was not higher, than in large cohort studies. In patients with uninterrupted OAK and low stroke risk TOE prior to CA could be omitted.