Table 2.

FT‐IR parameters in acute and chronic myocardial infarction (MI)

Acute MI		Chronic MI
Parameters	Tissue correlation	Parameters	Tissue correlation
Variations of the peak of GAG/protein ratio	Early tissue modification in infarcted regions	Increase of the band intensity at 1,082 cm−1 and at 1,662 cm−1 in the region of 31‐helix of collagen	Collagen deposition
Reduction of C═O stretching vibrations of: phospholipids (1,738 cm−1) nucleic acids (1,721 cm−1)	Loss of cellular components of the cardiac tissue (myocytes, quiescent fibroblasts)	Variation of the CH2/CH3 peak ratio CH2 at 2,852–2,926 cm−1 CH3 at 2,956 cm−1	Reduction of the lipid content respect to collagen fibrotic tissue
Modification of protein secondary structure	Modification of ECM proteins	Increase of absorption at 1,638 cm−1 in a spectral region of collagen I triple helix	Fibrotic tissue