Evaluation of LA thrombi and time to the repeat ablation
The absence or presence of TEE evaluation and the time to repeat ablation in each patient are shown in Figure 1. Interestingly, the prevalence of TEE examination became predominant after 180 days to repeat ablation. Most patients underwent TEE examination at repeat ablation when performed more than 1 year after the first session; however, some patients refused to undergo the examination because of difficulty in swallowing the probe (this was mostly their experience in the first session). Figure 2 demonstrates the evaluation of thrombi by each imaging modality and the time to repeat ablation in each patient. All but one patient received at least one imaging modality to exclude thrombi in repeat ablation at > 1-year. The remaining patient was a 57-year-old man with paroxysmal AF. Given the low risk of this patient (CHADS2 score of 0) and continuous administration of DOAC after the initial ablation, imaging evaluation prior to the repeat ablation was precluded. The patient underwent successful repeat ablation without adverse events.
The evaluation of LA thrombi based on the specific time to repeat ablation is shown in Figure 3 and Table 5. The rates of TEE and any imaging modality evaluation were 5.0%, 11%, 21%, 84%, and 91%; and 18%, 33%, 49%, 98%, and 99% for a time to repeat ablation of ≤60 days, ≤90 days, ≤180 days, >180 days, and >1 year, respectively. All three cases of thrombi had been scheduled for repeat ablation >180 days after the first procedure. None of the patients who were not evaluated by any imaging modality prior to the repeat session had thromboembolic events.
Figure 4 shows an evaluation of the clinical factors associated with undergoing TEE and any imaging modality during repeat ablation. Patients with non-paroxysmal AF were significantly more likely to undergo TEE and any imaging modality evaluation than those with paroxysmal AF (TEE, 85% vs. 73%, p = 0.001; any imaging, 70% vs. 51%, p < 0.001). Moreover, a history of thrombus detection before the first ablation (TEE, 100% vs. 57%, p = 0.005) and time to repeat ablation >180 days (TEE, 84% vs. 21%, p < 0.001; any imaging, 98% vs. 49%, p < 0.001) were significant factors for suggesting TEE and imaging evaluation at the repeat ablation.
The sample was divided into patients with a time repeat ablation ≤180 days and >180 days, and we compared the examination data between these two groups (Table 6). Changes in CHADS2and CHA2DS2-VASc scores between the first and repeat sessions were more evident in the late ablation group than in the early repeat ablation group. The incidence of clinical events after the first session was significantly higher in the late repeat ablation group than in the early ablation group (26% vs. 18%, p = 0.002). Although cardioversion for atrial arrhythmia was the most frequent event, other events also occurred frequently in the late ablation group (9.2% vs. 3.1%, p = 0.003).