Significance of the occurrence and timing of ERAT
It is difficult to discriminate early ablation failure from transient ERAT, which may be related to acute myocardial injury, subsequent inflammation response following radiofrequency ablation or cryoablation, and temporary abnormality in cardiac autonomic function.7,19,22-24 ERAT should not be classified as an ablation failure if it occurred during the blanking periods. However, several studies have shown that the presence of ERAT was associated with LR of AF in patients undergoing catheter AF ablation.18-20,25 The timing and frequency of ERAT within the blanking period are also important predictors of LR.
Several studies reported that early repeat ablation in patients who experience ERAT led to improved AF-free survival.26,27DAS28 et al. found that reconnection of the pulmonary veins was significantly higher in patients who experience ERAT beyond the first four weeks following catheter ablation. ERAT occurring after the first four weeks of catheter ablation was associated with an increased risk of LR. A 3-month blanking period is too long to be attributed as transient atrial changes after catheter or surgical AF ablation. There were various attempts to determine the optimal timing of the blanking period because the occurrence of ERAT in patients within three months following catheter AF ablation is associated with LR.20,29 Alipur29 et al. examined 636 consecutive patients who received catheter AF ablation; ERAT occurred in 31.4 % of the patients during the three- month blanking period and, most commonly, within the first two months after catheter ablation. Patients with ERAT were significantly more associated with LR than those without ERAT (73.1% vs. 24%; p =0.0001). According to the timing of ERAT, the rate of LR was one-half of the patients who experienced ERAT within the first month, whereas it was 76% within the second month, and 92% within the third month (p =0.001). Same investigators identified a cut-off of 23 days as the optimal blanking period.
Conversely, a shorter blanking period can lead to unnecessary early repeat ablation. We found that two-third of patients with ERAT occurring within the second month remained free of LR. The cut-off value in the first month could be short enough to achieve atrial reverse remodeling in maintaining sinus rhythm. Delayed maturation of the ablative lesions occurred up to two months after catheter ablation30; markers of inflammation continuously increase at the first week post-ablation and tend to decrease at the first month post-ablation.22,23 The transient autonomic dysfunction in heart rate variability persisted for at least three months after AF ablation.31 Furthermore, patients who underwent cardiac surgery had more extensive atrial scarring/fibrosis and frequent development of non-PV triggers than those who underwent catheter AF ablation.32
Our study provides the optimal cut-off value of blanking periods using ROC curve analysis. A cut-off value of 58 days indicated the highest discriminatory potential for the timing of ERAT that predicted LR after three months post-ablation. According to our data, ERAT within the blanking period of 58 days was associated with LR of AF (unadjusted HR 15.06, 95% CI 6.02-37.69, p <0.001). However, the purpose of the blanking period may be to reduce unnecessary repeat ablation. One-half of the patients who experienced ERAT within 58 days had AF-free survival. There is a lack of randomized clinical trials to define the optimal blanking periods in patients undergoing surgical or catheter AF ablation.
This study has several limitations that need to be addressed. First, we did not use intensive monitoring systems such as implantable loop recorder or transtelephonic monitoring to rule out asymptomatic ATA recurrences during the third month post-maze procedure. Second, our data did not include histories of medications that might influence clinical outcomes. Finally, our study was a small, observational, and non-randomized single-center study. Thus, large-scale studies are needed in the future to fully evaluate the relationship between the blanking period and LR in post-maze procedure patients.