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