Efficacy of ablation in patients with LVAs
As described above, although clinical outcomes were worse in patients without LVAs after initial PVI than in the group with LVA after multiple sessions, when patients with LVAs were compared with each other, a significant difference in clinical outcomes was seen after additional procedures, depending on the extent of the LVA.
Although PV reconnection is still considered a major cause of AF recurrence after initial ABL19, this factor seems to have diminished in terms of post-retreatment outcomes. At repeat procedures, the operator used his or her own discretion to determine treatment strategy for non-pulmonary veins, and most of the ablation targeted the LVA. This result suggests that LVA ablation, linear ablation, and CFAE are effective beyond PVI. 4,5
It has been reported that LVA is associated with fibrosis of the left atrium. Extensive LVAs were associated with more residual fibrosis.20 Development and progression of atrial fibrosis, which plays an important role in AF maintenance, is the hallmark of structural remodeling in AF. The presence of extensive LVAs can lead to multiple or complex areas of arrhythmogenicity. Extensive LVAs could have increased the area that could not be treated by ablation therapy, which might have resulted in poor clinical outcomes.
On the other hand, it must also be considered that fibrosis may simply be the final step of a remodeling cascade which includes myocyte architectural changes, ion channel dysfunction, connexin disarray and disruption of fiber orientation, all of which might precede scarring but not be seen on voltage mapping or imaging. 20 Based on this concept, the extent of an LVA might indicate the progression of fibrosis throughout the atrium. This might in turn suggest that patients with extensive LVAs are more likely to develop new arrhythmogenic features in the future.
The results of our study suggest that the benefit of beyond PVI therapy applies to patients with moderately advanced remodeling, such as those in group B. Table 2 and Figure 3 show that group C, with extensive LVAs, had a high recurrence rate even when PVI was complete. This suggests that clinical outcomes in patients with extensive LVAs are not yet sufficient, even with additional treatment of PVIs with high durability. Ablation therapy can also create new iatrogenic LVAs, which may limit the effectiveness of treatment in cases that already have extensive LVAs. These cases may require concomitant use of appropriate anti-arrhythmic drugs, in addition to ablation therapy.