The threshold of epicardial group was significant higher than endocardial group at the time of procedure (0.62 ± 0.22 V vs 0.78 ± 0.45 V; p = 0.01, before 6 weeks (0.88 ± 0.24 V vs 1.47 ± 0.52 V; p < 0.001), after 6 weeks (0.87 ± 0.24 V vs 1.56 ± 0.59 V; p < 0.001) and after 3 years (0.86 ± 0.32 V vs 1.33 ± 0.74V; p < 0.001).