TGFB1 and atrial fibrillation: The pooled analysis of included studies showed that plasma TGF-β1 levels in the patients with AF was significantly higher than those without AF in both analyses; continuous variable (SMD 0.67; 95%CI 0.29–1.05) with significant heterogeneity across studies (I2 = 91%, P<0.00001) (Fig 2) and categorical variable (OR 1.01, 95% CI 1.01–1.02) with moderate heterogeneity across studies (I2 = 62%, P = 0.05) (Fig 3).