3.2 Comparisons of DC in patients with and without AF recurrence
A total of 7 studies reported the data on DC prior to ablation, and the pooled mean difference estimated with the random-effect model between recurrence and non-recurrence groups was not statistically significant (Figure 2A; WMD, 0.34; 95%CI, -0.12 to 0.79; P = .15), suggesting the comparability of DC was achieved at baseline. Similar results were retrieved in the sensitivity analysis (Supplement 1A).
The data on DC within 3 days post-ablation were reported in 6 studies involving 748 subjects. The pooled mean difference assessed with the random-effect model was 1.0 (Figure 2B; 95%CI, 0.33 to 1.67; P < .01), indicating that patients with AF recurrence had the higher DC within 3 days post-ablation in relation to those without AF recurrence. Since significant heterogeneity was observed between these studies (I 2 = 97.5%, P < .01), the subgroup analysis was performed in accordance with the periods of AF recurrence. The pooled mean difference in DC between ablation-treated patients with and without late recurrence was 0.71 (95%CI, 0.53 to 0.88; P < .01) with marginal heterogeneity (I 2 = 0.0%, P = .83). The higher mean difference between participants with and without early recurrence was observed despite only one study (WMD, 2.6; 95%CI, 2.4 to 2.8; P< .01). In the sensitivity analysis, it was also suggested that the severe heterogeneity was associated with the study involving ablation-treated patients with early recurrence (Supplement 1B).
There were 4 studies involving the DC data on ablation-treated patients after 3 months of follow-up. The pooled mean difference estimated with the fixed-effect model was 1.54 (Figure 2C; 95%CI, 1.11 to 1.96;P < .01) with limited heterogeneity (I 2 = 48.4%, P = .12), indicating that the higher DC after 3 months post-ablation was observed in patients with late recurrence compared to those without recurrence. In the sensitivity analysis, the results were similar (Supplement 1C). Publication bias was illustrated with funnel plots (Supplement 2).
Two studies reported the DC data on AF patients after 6 months of follow-up, and the results were controversial. DC was higher in radiofrequency-ablation-treated patients with AF recurrence compared to those without recurrence (5.89 ± 1.65 ms vs 3.97 ± 0.98 ms, P< .05), whereas there was no significant difference between cryoballoon-ablation-treated patients with and without AF recurrence (3.7 ± 1.1 ms vs 3.8 ± 1.6 ms).17,23 Changes in DC among patients with and without AF recurrence were illustrated in Figure 3.