Fig. 2. Enhanced fibrotic remodeling in the myocardium of human METH-user heart autopsy tissues.

a Masson’s Trichrome staining was conducted in non-METH and METH user LV sections to assess the interstitial and perivascular fibrosis in the myocardium. Formalin-fixed, paraffin-embedded LV autopsy sections (5 µm) from non-METH (n = 7), and METH users (n = 34) were used for Masson’s Trichrome staining. The METH user group consists of heart samples from patients who died from acute METH intoxication/overdose and patients who were positive for METH following toxicology studies carried out in the case of accidental, combined drug overdose, or acute myocardial infarction-related causes of death. Representative left panel images to demonstrate the extent of fibrosis (in blue) in the LV perivascular region, and right panel images show the fibrosis (in blue) in the interstitial space in the same non-METH and METH user hearts. Scale bar: 100 µm. b Dot plot represents the individual values of the quantified percent fibrosis area in Masson’s Trichrome stained LV sections in non-METH (n = 7) and METH (n = 34) user groups. The size of the fibrosis area (blue-stained area) relative to the total myocardium area was measured in 10–15 high-magnification microscopic fields (×10) for each heart section and averaged for analysis. P values were determined between non-METH and METH groups by constructing multiple linear regression analysis with models adjusted for age, sex, race, heart weight, body weight, height, and body mass index. P < 0.05 between groups was considered statistically significant. Data are expressed as mean ± SEM.