Abstract:
Introduction: Larger left atrial appendage (LAA) ostium area
and greater left atrial (LA) volume have been associated with an
increased risk of ischemic stroke. Catheter ablation (CA) of atrial
fibrillation (AF) leads to morphological and functional changes within
the LA and LAA, some of which are not well studied. Here, we present
findings regarding post-ablation changes of the LAA ostia and correlate
them with various LA, LAA and left ventricular (LV) functional and
morphological metrics.
Methods : This retrospective analysis included patients
scheduled to undergo first-time radiofrequency CA for AF. Catheter
ablation techniques included PVI with or without additional ablations.
Cardiac magnetic resonance imaging (CMR) was used to assess LA, LAA and
LV morphology and function, including LAA ostium area, LA/LAA volume and
volume index, LA ejection fraction, LA strain, and LV ejection fraction.
A Kruskal-Wallis test was used for correlating LAA ostial dimensions
with other LA morphological and functional metrics. The t-test or
two-sample Wilcoxon test were used to compare LA and LAA morphological
parameters.
Results : A total of 101 patients with AF were included in this
study. The mean age was 60.1 ± 11.1 years, 69% were male, the average
BMI was 29.22 ± 5.08. The LAA ostial area reduced significantly from
3.84 ± 1.15 cm2 before ablation to 3.42 ± 0.96
cm2 after ablation (p=0.0004). This reduction was
asymmetrical, as the minor axis length decreased from 1.92 cm to 1.77 cm
without significant changes in the major axis. LVEF increased from a
pre-ablation average of 48.26% to a post-ablation average of 53.62%
(p=0.015). Correlation of pre-ablation LVEF and LAA ostium area showed a
near-significant negative trend (r=-0.21, p=0.083). LAEF correlated
negatively with LAA ostial area (r=-0.289, p=0.0057), total LA strain
(r=-0.248, p=0.0185), and passive LA strain (r=-0.208, p=0.049).
Conclusion: There is a significant asymmetrical reduction of
the LAA ostial area after AF ablation that is independent of LVEF
changes. Larger LAA ostial area was associated with lower LAEF and LA
strain. Remodeling of the LAA after AF ablation may help account for
reduced risk of stroke and increased cardiac function.
Keywords : Atrial Fibrillation, Left Atrial Appendage, Atrial
Remodeling, Atrial Myopathy, Cardiac MRI