Po-01-228 clinical significance of structural remodeling concerning substrate characteristics and ablation outcomes in patients with atrial fibrillation and mitral regurgitation

Mitral regurgitation (MR), which causes volume and pressure overload in the left atrium, has been shown to induce left atrial dilation, increasing the risk and likelihood of atrial fibrillation (AF). Catheter ablation of AF may be a potential method to improve the severity of MR in AF patients. To define the clinical significance of structural remodeling of the left atrium on substrate characteristics and ablation outcomes in patients with AF and MR. Patients with AF and moderate to severe MR who underwent catheter ablation from 2011 to 2021 were retrospectively included in the study. Patients' baseline characteristics and electrophysiological features were examined. The patients were classified as group 1 with improved MR (trivial/mild MR after ablation) and group 2 with significant residual MR (MR not improved). The LA was divided into 7 prespecified segments. The scarred segment was defined as more than 50% of the area with bipolar scar after ablation (<0.5 mV). Fifty patients with moderate or severe MR (age 60.2 + 11.4 years, males 21 [65.6%], severe MR 12 [24%]) were included in the study. The degree of MR was improved after ablation in 32 patients after a mean duration of 7.8 + 6.4 months (group 1) and not improved after ablation in 18 patients (group 2). Group 1 patients had a lower CHA2DS2-VASc score (1.7 ± 1.5 vs. 2.7 ± 1.5, P = 0.005) and had a lesser incidence of hypertension (28.1 % vs. 66.7 %, P = 0.007) and diabetes mellitus (3.1% vs. 22.2 %, P = 0.031) as compared to group 2 patients. Electroanatomic three-dimensional (3D) mapping showed that group 1 patients demonstrated less scars in the posterior bottom of the left atrium compared to group 2 patients (12.5 % vs 66.7 %, P < 0.001 ). Group 1 patients also had less AF recurrence compared to group 2 patients (50 % vs 66.7 %, P = 0.264), but time to recurrence of AF was similar between both groups (group 1 17 + 22.2 months vs. group 2 18.6 + 19.8 months, P = 0.847). After multivariate logistic regression analysis, a posterior bottom scar in the left atrium predicted refractory MR (OR 109.302, 95% CI 3.698 - 3230.223, P = 0.007) despite successful AF ablation. Most patients with AF and moderate or severe MR showed improvement of MR to trivial or mild MR within one year after AF ablation. A scar involving the posterior bottom of the left atrium is associated with poor recovery of MR.Tabled 1Univariate and multivariate logistic regression analysis for predicting refractory MR after AF ablationUnivariate AnalysisMultivariate AnalysisOR95% CIP-valueOR95% CIP-valueAge0.9650.913 - 1.0200.208Sex2.3860.732 - 7.7800.149Hypertension5.1111.469 - 17.7800.019.7890.395 - 242.7810.164Diabetes Mellitus1.2080.182 - 8.0020.844Dyslipidemia1.1540.313 - 4.2570.83Chronic Kidney Disease1.8750.241 - 14.5900.548Prior Stroke0.6750.117 - 3.8940.66Cavotricuspid Isthmus ablation0.7280.193 - 2.7500.64CFAE0.8670.189 - 3.9810.854LA linear ablation0.6360.197 - 2.0580.45SVC isolation1.8750.241 - 14.5900.548LA Roof scar0.7310.218 - 2.4440.611LA Anterior Wall scar1.4170.444 - 4.5210.556LA Septal scar1.0290.322 - 3.2900.962LA Posterior scar1.6070.502 - 5.1410.424LA Posterior Bottom scar52.5008.574 - 321.457< 0.0001109.3023.698 - 3230.2230.007LA Lateral Wall scar3.0000.907 - 9.9200.0720.8790.050 - 15.5800.93Baseline Left Atrial Diameter1.0090.935 - 1.0890.825Baseline Left Ventricular Ejection Fraction0.9260.850 - 1.0100.0830.8910.739 - 1.0760.23AF Recurrence4.5001.211 - 16.7190.02524.290.442 - 1335.5110.119*The multivariate regression model was calculated using multiple logistic regression stepwise analysis (included all variables with P<0.1). **LA, left atrium; AF, atrial fibrillation; CFAE, complex fractionated atrial electrogram; SVC, superior vena cava; OR, odds ratio; CI, confidence interval Open table in a new tab