Degree of Fibrosis in Human Atrial Tissue Is Not the Hallmark Driving AF

Figures

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  Figure 1. H&E staining reveals no increase in endo-perimysial fibrosis. In (A); representative example of cardiac bundle and perimysial space in human atrial tissue. Circle presents a cardiac bundle, white arrow shows perimysial space, and black arrow shows endomysial space. No significant difference between stages of AF and control SR group in terms of endomysial fibrosis (N = 8, SR; N = 8, ParAF; N = 8, PerAF; N = 5, LS PerAF) (B), and perimysial fibrosis (N = 8, SR; N = 8, ParAF; N = 8, PerAF; N = 5, LS PerAF) (C); respectively, p = 0.77 and p = 0.7542. SR = control group, ParAF = paroxysmal atrial fibrillation, PerAF = persistent atrial fibrillation, LSPerAF = longstanding persistent atrial fibrillation. Statistical tests used: ANOVA.

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  Figure 2. Picrosirius red and H&E stainings reveal no increase in fibrosis. No significant difference between various stages of AF and the control SR group in terms of the amount of fibrosis (N = 18, SR; N = 13, ParAF; N = 18, PerAF; and N = 13, LS PerAF) (A) and cardiomyocytel diameter (N = 12, SR; N = 9, ParAF; N = 11, PerAF; and N = 9, LS PerAF) (B); respectively, p = 0.12, p = 0.54. Picrosirius red staining in different stages of AF (C). In (D), yellow line shows the measurement of the cardiomyocyte diameter, H&E staining. SR = control group, ParAF = paroxysmal atrial fibrillation, PerAF = persistent atrial fibrillation, LSPerAF = longstanding persistent atrial fibrillation. Statistical tests used: ANOVA.

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  Figure 3. Cardiac myofibroblast (αSMA) marker and metalloproteinase inhibitor factor (TIMP). No significant difference was observed between various stages of AF and the control SR group regarding αSMA (N = 91) and TIMP (N = 89); respectively p = 0.99, (B), and p = 0.41, (D). Representative blot images for αSMA and TIMP expression are illustrated in (A,C), respectively. SR = control group, ParAF = paroxysmal atrial fibrillation, PerAF = persistent atrial fibrillation, LSPerAF = longstanding persistent atrial fibrillation. Statistical tests used: ANOVA.

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  Figure 4. Fibroblast marker (NCAM and collagen crosslinking promoter (LOX). No significant difference was observed between various stages of AF and control SR group, in terms of NCAM (N = 76) (B) and LOX (N = 92) (D), respectively, p = 0.83 and p = 0.11. Representative blot images for NCAM and LOX expression are illustrated in (A,C), respectively. SR = control group, ParAF = paroxysmal atrial fibrillation, PerAF = persistent atrial fibrillation, LSPerAF = longstanding persistent atrial fibrillation. Statistical tests used: ANOVA.

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  Figure 5. Blood based quantification of ratio CITP/MMP1. Ratio between the sub product of collagen degradation (CITP) and its promoter (MMP1) was assessed (N = 20, ParAF; N = 27, PerAF; N = 18, LS PerAF; and N = 47, SR) in line with the previous endpoints comparable values were observed at different stages of the AF and control SR group, p = 0.07. SR = control group, ParAF = paroxysmal atrial fibrillation, PerAF = persistent atrial fibrillation, LSPerAF = longstanding persistent atrial fibrillation. Statistical tests used: ANOVA.

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  Figure 6. Correlogram with correlation coefficients for histological fibrosis markers and electrophysiological endpoints. No strong correlation (−0.8 < R < 0.8) was visualized between histological fibrosis markers and electrophysiological endpoints (N = 35). Statistical tests used: Spearman correlation test.

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  Figure 7. Spatial analysis of electrophysiological and fibrosis parameters in the LAA of patients with ParAF, PeAF, and LS PerAF. In the left panels, high resolution epicardial mappings reveal simultaneously color-coded degree of voltage, and black lines represent block and delay lines; on the right panels, correspondent LAA tissue was stained with picrosirius and percentage of total fibrosis was determined for each subdivision of the slide. Black crosses indicate sub-sectional areas presenting the highest amount of fibrosis.