Radiofrequency Ablation of Atrial Fibrillation

Abstract

Background-Several approaches have been developed for radiofrequency catheter ablation of atrial fibrillation, but the correct intraprocedural end point is still under debate, and few data exist about the destiny of ablation lesions over time. The aim of the present study was to evaluate the long-term maintenance of intraprocedural end points of ablation procedures. Methods and Results-Inclusion criteria were (1) a previous ablation procedure of pulmonary vein (PV) encircling performed for drug-refractory persistent atrial fibrillation; (2) a "complete" intraprocedural end point, which consisted of voltage abatement inside the lesions, PV disconnection, and exit-block pacing from inside the lesions, attained in all PVs; and (3) stable sinus rhythm documented during a minimum follow-up of 2.5 years after the procedure. Twenty volunteers were selected (12 males, mean age 59Ϯ7 years) and underwent a repeat electrophysiological study. After a follow-up of 36.4Ϯ4.7 months, complete voltage abatement was maintained around 32 PVs (40.0%), PV disconnection persisted in 12 (37.5%) of the previously isolated PVs, and exit block was present in 39 PVs (48.7%). Ten patients who underwent a redo ablation procedure because of recurrences of atrial fibrillation were used as the control group. Differences in intraprocedural end-point maintenance between the 2 groups were not statistically significant. Conclusions-Common intraprocedural end points such as voltage abatement, PV disconnection, and exit block persist only in a limited number of patients, even when the outcome is favorable during follow-up. Further investigation will be required to determine whether such data will have implications for ablation strategies.

Vagal Modification Can Also Help Prevent Late Recurrence of Atrial Fibrillation After Segmental Pulmonary Vein Isolation

“…On the other hand, it has been recently reported that there are no statistically significant differences in the persistence of PV disconnections in the patients with and without recurrence after an AF ablation procedure, 17 although that was not demonstrated in the present study. One possibility that may explain the results of these 2 studies is that recovery of the electrical connections happens to occur in the arrhythmogenic PVs in the patients with AF recurrence, whereas it does not occur in the arrhythmogenic PVs in the patients without AF recurrence.…”

Electrotonic coupling of excitable and nonexcitable cells in the heart revealed by optogenetics

“…Electrotonic coupling may interfere with the success of therapeutic interventions, such as atrial ablation, by causing scars to become "electrically transparent" with time (perhaps, in particular, between ablation points, where scars are most narrow). Such "disappearance" of intraprocedurally confirmed lesions seems to occur in a majority of atrial ablation patients (8). Although atrial ablation lines, placed to electrically separate adjacent muscle regions, may perhaps be discontinuous to begin with (even if, intraprocedurally, block is achieved), de novo formation of electrical conduction across continuous and fully transmural scars after surgery has also been reported (9,10).…”

“…Possible functionality of connexin-based junctions was indicated in rabbit atrium, where dye diffusion between heterotypic cell types has been reported (6), and in mouse ventricle, where fibroblast-specific conditional connexin 43 knockout reduced transmission of injected current from healthy to scarred tissue (7). A number of clinical observations, such as transscar electrical conduction after atrial ablation (8) or surgical repair of congenital heart defects (9) and transplantation (10), in addition to experimental findings of electrical conduction into postinfarct (11) and cryoinjury (7) scars and along implanted tissue grafts (12,13) would be in keeping with a (passive) contribution by nonmyocytes to cardiac AP conduction. Functional heterocellular electrotonic coupling thus far has been shown conclusively in vitro only [where it is aided by phenotype conversion and connexin overexpression of cultured fibroblasts (14)(15)(16)(17)].…”

An Increase in Right Atrial Magnetic Strength Is a Novel Predictor of Recurrence of Atrial Fibrillation After Radiofrequency Catheter Ablation

“…31 The other study reported a crucial fact that PV disconnection persisted in only ~40% of the previously isolated PVs even in patients with stable maintenance of sinus rhythm. 32 These data suggest that the presence of an arrhythmogenic substrate in addition to PV reconnection makes the atria more susceptible to recurrent AF than does PV reconnection alone. If one applies the results from the present study to this notion, the fluctuation of magnetic strength in the RA might reflect the presence of an arrhythmogenic substrate.…”