Results
Of the 259 patients (mean age, 60.6 ± 11.4 years; 50.6% male), 127
(49%) had ERAT during the 3-month blanking periods. Among the patients
with ERAT, the timing of the ERAT was during the first month post
ablation in 65 patients (51.2%), during the second month in 14
(11.0%), and during the third month in 48 (37.8%). Baseline
demographic and clinical characteristics of the study population are
detailed in Table 1. Patients with ERAT were older (mean, 63.1 ± 9.5 and
58.2 ± 12.5 years, respectively; p <0.001) and had
larger left atrial size (mean, 56.1 ± 12.1 and 52.3 ± 8.9 mm,
respectively; p = 0.004) than those without ERAT. In addition, a
significantly greater proportion of patients with ERAT had a history of
persistent AF (92.1% and 74.2%, respectively; p<0.001).
The following operative and postoperative risk factors were more
commonly recorded in patients with ERAT than in those without ERAT
(Table 2): longer cardiopulmonary bypass (CPB) time (181.3 ± 63.3 and
154.8 ± 59.2 minutes, respectively; p =0.001) and aortic
cross-clamp (ACC) time (128.1 ± 53.6 and 108.2 ± 45.3 minutes,
respectively; p =0.001) and more postoperative pulmonary
complications and reoperations for bleeding (11.0% and 3.0%; p= 0.022). Patients with ERAT received bi-atrial surgical AF ablation
more frequently (80.3% and 62.1%, P = 0.002) and used more
amiodarone during blanking periods (82.7% and 21.2%, P<0.001).
The factors independently associated with ERAT after multivariate
logistic analyses are shown in Table 3. Older age (per year: odds ratio
[OR], 1.03; 95% CI, 1.00-1.06; p =0.012), history of coronary
artery disease (CAD) (OR, 6.98; 95% CI, 1.38-35.36; p =0.019),
history of persistent AF (OR, 3.18; 95% CI 1.36-7.43; p =0.008),
larger left atrial size (OR, 1.03; 95% CI, 1.00-1.06; p =0.022),
longer CPB time (OR, 1.00; 95% CI, 1.00-1.01; p =0.033), and
reoperation for bleeding after cardiac surgery (OR, 3.00; 95% CI,
1.41-6.37; p =0.004) were associated with the occurrence of ERAT
during the three-month blanking periods.
At the 12-month follow-up, 74 of 127 patients (58.3%) with ERAT were
free from late AF recurrence compared with 129 of 132 patients (97.8%)
without ERAT (p <0.001; Figure 1A). AF-free survival rate was
95.4%, 64.3%, and 8.3% among those who had ERAT in the first, second,
and third months, respectively (p <0.001; Figure 1B). To
evaluate the role of ERAT as a predictor contributing to LR, the
univariate Cox regression model was performed according to the
occurrence and timing of ERAT (classified by month) after surgical
ablation. After adjustment for the occurrence of ERAT, age (per year:
HR, 1.04; 95% CI, 1.00-1.07; p =0.025), male gender (HR 1.77;
95% CI, 1.02-3.09; p =0.043), larger LA size (HR, 1.04; 95% CI,
1.02-1.06; p <0.001), and the occurrence of ERAT (HR,
17.73; 95% CI 5.48-57.34; p <0.001) were shown to be
independent risk factors for LR. In addition, adjusted analyses were
conducted using the timing of ERAT within the blanking periods. The
occurrences of ERAT during the second (HR, 16.70; 95% CI, 3.98-70.22;p =0.001) and third months (HR, 119.75; 95% CI, 36.25-395.59;p <0.001) were the most powerful independent predictors
of LR (Table 4).
The ROC curve that determined the cut-off value of the blanking period
is shown in Figure 2. The AUC was 0.938 (95% CI: 0.893 to 0.983,p < 0.001), showing excellent discrimination. The ideal
cut-off value for the blanking period was 58 days. The occurrence of
ERAT beyond 58 days predicted LR with a sensitivity of 93.2% and
specificity of 86.8%