Evaluation of a Computed Tomography-based Technique for Predicting Atrial Fibrillation Recurrence Following Ablation Using an Adjusted Skeletal Muscle Index.

Background: This research focuses on the unresolved question of how low muscle mass influences the likelihood of atrial fibrillation (AF) recurrence after ablation treatment. Despite the growing body of evidence highlighting the importance of muscle mass in cardiovascular health, the specific impact of low muscle mass on the recurrence of AF following ablation has yet to be well-established. Thus, this study evaluated the relationship between a low computed tomography (CT)-based skeletal muscle index (SMI) of muscle sites at the fourth thoracic level (T4-SMI) and AF recurrence post-radiofrequency ablation. Furthermore, this study aimed to determine whether the T4-SMI is a predictive marker for AF recurrence.

Methods: This study included 641 patients with AF who underwent radiofrequency ablation. T4 muscle sites were determined using SliceOmatic software. Height- and body mass index (BMI)-corrected SMIs were calculated.

Results: The lowest quartile in the T4-SMI group was defined for each sex as the "low SMI" group. The height-adjusted T4-SMI thresholds were 69.7 cm²/m² for males and 55.91 cm²/m² for females. The BMI-adjusted thresholds were 8.10 cm²/kg/m² for males and 5.78 cm²/kg/m² for females. After potential confounder adjustment, low T4-SMI was associated with a higher risk of AF recurrence. The correlation between T4-SMI (height) and AF recurrence was fully validated by constructing multiple models, and adjusting for different covariates barely altered the results. Fully adjusted models suggested that compared with the fourth T4-SMI (height) quartile, the risk odds ratio (OR) with a 95% confidence interval (CI) of the "low SMI" group was 1.57 (0.76-3.22). Finally, subgroup analysis and interaction according to gender, age, overweight/obesity, hypertension, or diabetes indicate that the differences between different layers are not significant.

Conclusions: Low CT-based BMI- or height-adjusted T4-SMIs were risk factors for AF recurrence post-radiofrequency ablation. A lower T4-SMI (height) significantly correlated with AF recurrence post-ablation, regardless of gender, age, or overweight/obesity. The height adjustment performed better than the BMI adjustment in that regard.