How to best assess ablation lesion formation with late gadolinium
Kurose et al. report on a lower number of gaps in RF-lesions compared to
Cryo-lesions as determined by late gadolinium enhancement MRI (LGE-MRI).
However, unlike claimed by the authors, there is ample evidence based on
LGE-MRI in this context. Most importantly we have specifically compared
RF and Cryo lesions in a recent case control study on AF Ablation. In
contrast to the results of Kurose et al., our study, despite larger
sample size, did not detect a difference in the number of gaps between
the two energy sources. While numerous factors may account for the
conflicting results, two points should be considered in particular. 1.
The time point of LGE-MRI at a mean of 55 days post ablation has never
been validated for chronic lesion formation, and is considerably earlier
than the validated and well-established 3-months timepoint chosen by
most groups. In fact, according to previous reports, gadolinium
enhancement at earlier time points may, at least in part, reflect a
transient inflammatory response rather than chronic scar formation. 2.
The method of Kurose et al. is based on the definition of an area of
healthy atrial tissue in each patient as an internal reference. However,
it appears almost impossible to define a truly healthy area in the
atrium of patients with atrial fibrillation. Thus the method is likely
to underestimate ablation-induced fibrosis in patients with advanced
disease and/or underlying pathologies and to overestimate it in younger,
rather healthy patients.