Optimizing pace-and-ablate: structural determinants of transmural lesion formation in atrial ablation
M T Takigawa, G N Nitta, R K Kato, M H Honda, R T Tateishi, I K Kawamura, M N Negishi, K G Goto, K I Ihara, T N Nishimura, K Y Yamao, S T Tao, I O Onishi, S M Miyazaki, S T SasanoAbstract
Background
The efficacy of radiofrequency (RF) catheter ablation depends on achieving transmural lesions. Pacing capture loss (PCL) is often used as a real-time indicator of lesion maturation; however, the optimal duration of RF delivery after PCL and the structural determinants governing whether PCL truly reflects transmurality remain uncertain.
Objective
Study 1: To compare lesion transmurality between 35 W and 50 W across different duration settings.
Study 2: To determine the optimal pacing output and post-PCL duration for the pace-and-ablate approach.
Study 3: To identify structural factors influencing true-positive lesions, defined as both PCL( + ) and transmurality( + ).
Methods
In a porcine atrial model, RF energy was delivered at 35 W or 50 W, with ablation terminated 0, 3, 5, or 7 s after PCL (3 mA pacing; partial 5 mA). Morphological and functional outcomes were evaluated by macroscopic observation and pacing testing. Associations among power, duration, pacing strength, and transmurality were analyzed using Fisher’s exact test, Cochran–Armitage trend analysis, and logistic regression.
Results
Study 1: At 50 W, lesion transmurality increased with longer post-PCL duration, reaching 100% after 5–7 s, whereas 35 W or early termination (0–3 s) frequently resulted in incomplete lesions (Figure A).
Study 2: At 50 W, 3 mA pacing with 5–7 s extension produced a higher transmurality rate than 5 mA with 0–3 s extension (81% vs 59%, p = 0.015) (Figure B).
Study 3: In multivariate analysis of 50 W–3 mA–5–7 s lesions (n = 86), wall thickness (p = 0.00019) and trabeculated anatomy (p = 0.0153) independently predicted false-positive PCL, whereas contact force, catheter orientation, and voltage indices were not significant (Figure C).
Conclusions
PCL indicates lesion maturation but overestimates transmurality when RF delivery stops immediately after capture loss. Extending ablation for ~5 s beyond PCL at 50 W ensures reliable concordance between functional and morphological transmurality. The predictive accuracy of PCL declines in thick or trabeculated atrial regions, highlighting the need to account for local structural complexity when applying the pace-and-ablate method.