Results:
Baseline Characteristics:
A total of 101 patients with AF
were included in the study. The mean age was 60.1 ± 11.1 years, 69%
were male, the average BMI was 29.22 ± 5.08 and the average body surface
area (BSA) was 1.83 ± 0.68 m2. Of all patients, 23.8%
had heart failure with reduced ejection fraction (HFrEF), 6.9% had
heart failure with preserved ejection fraction (HFpEF), 46.5% had
hypertension (HTN), and 7.9% had a history of stroke or other systemic
thromboembolism (SSE). 33.7% of patients underwent some form of
cardioversion and 38.6% had failed a trial of antiarrhythmic therapy.
The average left ventricular ejection fraction (LVEF) was 48.85%.
In terms of baseline left atrial characteristics, the mean LAVI was
38.66 ± 10.2 mL/m2 , the mean LA sphericity index was
73.6 ± 18.9, the mean LAA volume was 6.76 ± 4.47 mL, and the mean
fibrosis level was 15.51 ± 8.02%. Left atrial appendage shapes were
categorized into the popular “windsock” (6.93%), “cactus”(5.94%),
“chicken wing”(77.2%) and “cauliflower” (9.90%) categories (20).
The baseline characteristics of the LA, LAA, and LAA ostia in our study
cohort are given in Table 1.
LAA Ostium Dimensions
The average LAA ostium area was 3.32 ± 1.17 cm2. When
accounting for BSA, the indexed mean LAA ostium area was 1.67 ± 0.56
cm2/m2. Since LAA ostia can be
approximated with a centroid with a major and minor axis, the average
major axis length was 2.44 ± 0.48 cm, the average minor axis length was
1.72 ± 0.34 cm, with the average perimeter at 6.35 ± 1.17 cm.
When exploring the relationship between the LAA ostia characteristics
and various risk factors and comorbidities, patients with HFrEF had a
significantly larger LAA ostial area than patients without HFrEF (3.88
vs. 3.20 cm2, respectively, p=0.0148). This result
remained significant when comparing the LAA ostial area indexed by BSA
(1.89 vs. 1.60 cm2/m2, respectively,
p=0.0268). No statistically significant associations were found between
LAA ostial area and other risk factors or comorbidities. The analysis
results are presented in Table 2.
Left Atrial Appendage Ostium Dimensions and its Association
with Left Atrial Morphological and Functional Parameters
The LAA ostial parameters were further examined for their correlation
with LA and LAA morphological parameters. The LAA ostial area was shown
to have a moderate positive correlation with LA volume (r=0.31,
p=0.0017) and LAA volume (r=0.42, p<0.0001). LAA ostial area
was largest in patients with a “cauliflower” LAA shape morphology
(4.53 cm2 vs 3.30 cm2 [average of
other morphology classes], p=0.011). No association was found between
LAA ostial area and LA sphericity, LAVI or LA fibrosis level.
LAA ostial parameters were also correlated with LA functional metrics.
Total LAEF correlated negatively with LAA ostial area (r=-0.289,
p=0.0057). Indexed LAA ostial area was also negatively correlated with
total LA strain (r=-0.248, p=0.0185), and passive LA strain (r=-0.208,
p=0.049). There was a trend for negative correlation between LAA ostial
and active LA strain, but this was not statistically significant
(p=0.064).
Analysis results correlating LAA ostial parameters with LA morphological
and functional markers are presented in Tables 3A/3B and 4,
respectively. A selection of correlation analysis results from this
analysis are also shown in Figure 2.
Changes in Left Atrial Appendage Ostium Following Catheter
Ablation
A subgroup analysis on 37 patients who underwent pre- and post-ablation
CMR studies was performed. On average, the post-ablation CMR was
performed at 49.6 ± 26.7 weeks after procedure day. 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).
11 of the 37 patients (29.7%) experienced a reduction in ostial size to
below 3.5 cm2while the minor axis length of the LAA
ostia decreased from 1.92 cm to 1.77 cm after ablation (p=0.0004), the
major axis length did not demonstrate a significant reduction
(p=0.1139). Other LA and LAA structural and functional markers were also
examined in these patients and compared pre- and post-ablation. Other
parameters such as LA volume, LAA volume, LAEF and various components of
LA strain did not change significantly after ablation. This subgroup
analysis on pre- and post-ablation changes is given in Table 5.
Additional analysis was performed to examine LVEF change
pre-/post-ablation and its association with LAA ostium area. First, 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
pre-ablation LAA ostium area showed a near-significant negative trend
(r=-0.21, p=0.083). There was no correlation between the post-ablation
change in LVEF and the change in LAA ostium area (p=0.671). There was
also no correlation between the post-ablation change in LVEF and the
change in LAA ostium area (p=0.513). Results of this correlation
analysis are presented in Figure 3.