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 cm before ablation to
3.42 ± 0.96 cm 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.