Association between venous thromboembolism and atrial fibrillation: a Mendelian randomization study

Although previous observational studies have shown an association between venous thromboembolism (VTE) and atrial fibrillation (AF), the underlying causal relationship between them remains uncertain. This two-sample bidirectional Mendelian randomization (MR) analysis was performed to investigate the causal relationship between VTE and AF. The VTE dataset were obtained from FinnGen, including 9,176 cases and 209,616 controls. Meanwhile a genome-wide association study (GWAS) of 60,620 individuals with AF and 970,216 control subjects identified genetic variations associated with AF. The principal MR analytic approach used in this study is the inverse-variance weighting (IVW) method. Furthermore, we performed complementary MR analyses, including the MR-Egger, Weighted median (WM), and Weighted Mode. MR pleiotropy residual sum was applied to identify pleiotropy. The MR analysis showed suggestive causal associations between VTE and the risk of AF (p = 0.0245, OR [95%CI]: 1.027 [1.003, 1.051]). The reverse MR analysis found that genetic susceptibility to AF was not significantly associated with VTE, as determined by the IVW method (p = 0.7773). The robustness of these findings was corroborated through MR sensitivity analyses. There is a unidirectional causal relationship between VTE and AF, meaning that VTE is a causal risk factor for AF, whereas no effect of AF on VTE was identified.