Table 1. ECM changes in the electrical conduction system and their functional consequences.

ECM component modification	Effect	Reference
↑ Collagen Type I	Gap junction remodelling	[26]
↓ Connexin-43	Altered cell-cell communication and increased fibroblasts activity	[26]
↑ Fibronectin	Fibrosis	[40]
↑ α1 and α5 integrin	Fibrosis	[41]
↓ Elastin	Sinus atrial node fibrosis	[45]
↑TGFβ1	Interstitial fibrosis	[45]
↑TNFα
↓ MMP-2
Fatty infiltration and flogistic infiltrate	Sinus atrial node dysfunction	[44]

TGFβ1: transforming growth factor β1; TNFα: tumor necrosis factor α; MMP-2: metalloproteinases-2.