Baseline LA strain and AF recurrence
Analysis of the 17 included studies revealed that the MD between
baseline LA strain in patients with post-ablation SR maintenance ((N=
1147, pooled mean (SD): 22.22% (10.64)) and those with AF recurrence
((N= 557, pooled mean (SD): 15.96% (9.77)) was statistically
significant (5.43%, 95%CI: 4.03-6.84%). Heterogeneity analysis showed
substantial heterogeneity (I2: 82.7%) (Figure 2).
We performed a sensitivity analysis, by including only the 12 studies
that were classified as high-quality, but no significant change was
noted compared to the overall results (Supplementary Figure 2). Also,
when we excluded two studies[15.27] which visually
introduced substantial heterogeneity, a more homogenous effect size
estimation emerged (mean difference: 6, 95%CI: 5.12-6.89,
I2:42.77%). Subgroup analysis was also performed by
dividing studies according to the methodology used for strain
measurement (apical 4 chambers view only versus biplane and the number
of LA segments assessed), a significant subgroup interaction was noted
(p=0.02) (Figure 3). The pooled effect sizes presented minimal
quantitative changes compared to the initial pooled effect size
estimation. Heterogeneity was almost eliminated in the smaller subgroups
of studies, but remained substantial in the larger subgroup of studies
that used the biplane method. Moreover, subgroup analysis was performed
based on the type of the ablation procedure that was used – 7 studies
using radiofrequency catheter ablation PVI alone versus 9 studies using
radiofrequency catheter ablation PVI plus additional lesions- but no
significant interaction was found (p=0.6). Subgroup analysis based on
the software used (9 studies using EchoPac and 8 studies using other
softwares) no significant interaction was noted (p=0.5). Finally, after
removing one subgroup of patients who underwent second
radiofrequency[13] catheter ablation procedure and
one study with mixed population (first and second radiofrequency
catheter ablation PVI)[14] heterogeneity remained
at the same levels (I2: 84.5%) with no significant
change in the effect size (MD: 5.36, 95%CI: 3.84-6.87).
Meta-regression analysis revealed no confounding effect of age (p=0.67),
male gender (p=0.34), number of PAF patients included (p=0.96), number
of hypertensive patients included (p=0.56) and baseline pre-ablation
strain (p=0.66). However a statistically significant negative
correlation was documented between the pooled effect size and the mean
baseline maximum LAVi (regression coefficient= -0.184, p=0.004, one
study where LAVi was measured using 3D echocardiography was
excluded[27]) (Figure 4).