MMP9 and atrial fibrillation: Finally, we examined the extent of fibrosis in LAA from patients with AF or SR and we found masson positivity (Figures 1F,G) and the expression of MMP-9 (Figure 1H), collagen Iα and collagen IIIα (Figures 1I,J) were upregulated and cardiac colour Doppler ultrasound indicated that LAESVI was increased (Figure 1J) and LAEF and LAFI were decreased (Figures 1K,L) in AF patients compared with SR patients.