We appreciate the scholarly comments by Ganesan et al. on our work1. Their first comment regards features of AF phase mapping. Our study actually focused on identifying novel organized areas in AF rather than on phase mapping2. We constructed vector field maps in AF from activation times, and uncovered distinct areas of within which activation propagates 1:1 despite overall fibrillatory disorder. We identified 3 spatial patterns of AF, which indicated progressively greater difficulty of terminating persistent AF by ablation. For reference only, some of these areas colocalized with regions identified by phase. Synchronous chiral and antichiral activation areas were indeed identified, but constructed from activation times not phase.
Ganesan raised the excellent point of how these results compare to patients in whom persistent AF did not terminate with ablation. We are in the process of performing this comparison3. In preliminary data, patients without AF termination showed a higher number of small organized areas than patients in the current study. It is possible that ablation at different targets may be beneficial in such cases.
As a third point, Ganesan discuss the issue of fluctuating organized sites in AF. We recently showed, in a separate study, that many organized sites in AF which fluctuate go on to recur in the same location with the same chirality over hundreds of cycles4. Such sites, which also often persistent for tens of cycles before disappearing4, would be unlikely to represent chance formation such as at lines of block5. Our study found that organized areas may fluctuate because of competing dominance between 2 or more sites 4. This is also observed by optical mapping of human AF with6 or without7 clinical baskets.
Finally, we agree with Ganesan that rotational elements in AF may terminate when wavefronts collide with inexcitable boundaries, as we have reported8. In the current study, we did not find that AF terminates by ablation at a distance from organizing centers, as suggested by Ganesan. Rather, elimination of secondary mechanisms by ablation left residual large areas of control (‘organized AF’), whose ultimate elimination led directly to AF termination.
Acknowledgments
We thank Ganesan et al for their interest in our work. Future work will track organized areas throughout mapping and ablation, and use these indices for prognosis and to guide therapy.
Funding: WJR is funded by National Institutes of Health (R01 HL122384 and R21 HL145500). SMN is funded by National Institutes of Health (R01 HL83359, K24 HL103800).
Footnotes
Disclosures
SMN reports intellectual property assigned to the University of California Regents and Stanford University. He also reports consulting from Abbott Inc., American College of Cardiology, Uptodate Inc, BeyondLimits.ai, TDK Inc. WJR reports intellectual property assigned to the University of California Regents
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