Significant Reduction of Atrial Defibrillation Threshold and Inducibility by Catheter Ablation of Atrial Fibrillation


  • This work was supported by a grant from the Korea Health 21 R&D Project, Ministry of Health and Welfare (A085136); the Basic Science Research Program (2010-0010537) run by the National Research Foundation of Korea (NRF) which is funded by the Ministry of Education, Science and Technology of the Republic of Korea; and research grant from Korean Society of Circulation.

Address for reprints: Hui-Nam Pak, M.D., Ph.D., 250 Seungsanno, Seodaemun-gu, Seoul, Republic of Korea 120-752. Fax: 82-2-393-2041; e-mail:


Background: Radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) has antiarrhythmic effects by multiple mechanisms. We hypothesized that RFCA curtails atrial defibrillation threshold (A-DFT) and postablation induction pacing cycle length (iPCL), making critical mass reduction one potential mechanism by which antiarrhythmic effect is achieved.

Methods: We included 289 patients with AF (male 77.9%, 55.7 ± 10.8 years old; 197 paroxysmal AF: 92 persistent AF) who underwent RFCA. A-DFT (serial internal cardioversion 2, 3, 5, 7, and 10 J) and iPCL (serial 10 mA 10-second atrial pacing with pacing cycle length 250, 200, 190, 180, 170, 160, and 150 ms) were evaluated before and after RFCA.

Results: (1) RFCA of AF reduced the A-DFT from 6.7 ± 3.7 J to 3.0 ± 3.0 J (P < 0.001). (2) AF ablation reduced AF inducibility from 95.4% before the procedure to 56.3% after the procedure (P < 0.001), and the iPCL from 194.8 ± 32.6 to 160.9 ± 26.2 ms (P < 0.001). (3) In patients who underwent a greater number of ablation lines, the post-RFCA A-DFT (P < 0.001) was lower, and %ΔA-DFT (P = 0.003) and proportion of atrial tachycardia (P = 0.022) were higher than those with a lower number of ablation lines.

Conclusion: AF ablation significantly reduced A-DFT, AF inducibility, and iPCL, and the degree of their reduction was related to the number of ablation lines. (PACE 2012;35:1428–1435)