Clinical factors associated with extensive LVAs
Although several methods for preoperative prediction of the presence of LVAs have been reported 21-23, the present study showed that widespread LVAs worsen the clinical prognosis. We identified the following as independent predictors of extensive LVAs: female, low BMI, and large LAD (Table 4). These factors have been reported to be related to LVAs in the past, and we discuss them here with reference to these reports.
These previous reports identified mechanisms underlying the sex differences in atrial fibrosis. 24 On histological analysis of atrial tissue, females showed stronger expression of CX40 than males, which indicates remodeling-induced change in connexins.25 In addition, fibrosis-related genes were upregulated in post-menopausal woman with AF. 26Clinically, females reportedly experience AF recurrence more frequently than males during long-term follow-up after AF ablation, likely due to non-PV arrhythmogenicity. 27
The reason why low BMI and large LAD are associated with extensive LVAs may be that they both reflect wall stress on the LA. As reported previously, LVA is a result of the progression of remodeling. LA remodeling in AF patients is suggested to be associated with continuous internally generated stretch and wall stress.9,28-30 Anatomical contact with external structures surrounding the LA provokes the perpetuation of AF by arrhythmogenic substrates in patients with persistent AF. 31,32 In patients with low BMI, the distance between the LA and external structures such as the vertebral bodies may be close enough to trigger the development of LVA.