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.