Left atrial substrate characterization in patients with atrial
fibrillation and hypertrophic cardiomyopathy: evidence for an extensive
Introduction. Data regarding the left atrial (LA) electroanatomical
substrate in patients with hypertrophic cardiomyopathy (HCM) and atrial
fibrillation (AF) are missing. In this electroanatomical mapping (EAM)
study, we evaluated the extent of LA fibrosis and its impact on catheter
ablation outcomes in patients with HCM and AF. Methods. High-density LA
EAM was performed during AF in 28 consecutive patients with obstructive
HCM and AF (42.9% displayed paroxysmal AF and 57.1% persistent AF).
After propensity matching (PS), 28 non-HCM patients with AF were
selected, and served as controls. Two different cut-off values of
bipolar signal amplitude were investigated for fibrosis characterization
(≤0.25 mV and ≤0.4 mV). HCM patients underwent pulmonary vein antral
isolation (PVAI) and roof line, while non-HCM patients PVAI only.
Results. After the 3-month blanking period, 10 HCM patients (35.7%)
displayed atrial arrhythmia recurrence. Univariate analysis revealed
that the extent of LA fibrosis was the only predictor of AF recurrence.
HCM patients with arrhythmia recurrence showed significantly greater low
voltage areas defined as either bipolar voltage ≤0.25 mV (22.5±10% vs.
5.5±6.4%, p=0.001) or ≤0.4 mV (32±13.9% vs. 5.9±5.1%,
p<0.001). The presence of low voltage areas ≤0.4 mV greater
than 14.1% of the total LA area also predicted arrhythmia recurrence
with excellent sensitivity (100%) and specificity (100%). After PS
matching with non-HCM patients, patients with HCM exhibited wider
fibrotic regions ≤0.25 mV compared to non-HCM patients (p=0.016).
Conclusions. High-density EAM reveals extensive LA fibrotic disease in
patients with HCM, an event with certain implications in catheter