Limitations
This study has potential limitations. First, the number of HCM patients
is relatively small. Second, our clinical follow-up regarding arrhythmia
recurrence following catheter ablation was based on 12-lead
electrocardiogram and 24-hour Holter monitoring, and therefore the true
recurrence rates may have been underestimated. Third, the identification
of fibrotic substrate using EAM is not fully developed, and displays
several limitations.15 The measured voltage depends on
the rhythm (sinus rhythm vs. atrial pacing vs. AF), the contact of the
electrode to the tissue, the thickness of the atrial myocardium, the
electrode size and spacing, the wave front direction, and other
variables.15 However, in our study, two low bipolar
voltage criteria were used for tissue characterization (the strict
criterion of ≤0.25 mV and the less strict but more commonly used of ≤0.4
mV). Finally, we did not use LGE-CMR in order to confirm that LA regions
with low bipolar voltage ≤0.4 mV
or ≤0.25 mV represent true atrial scar. However, EAM during AF has been
shown to correlate well with atrial scar detected by
LGE-CMR.16