Fig. 1

Representative photographs of the morphological changes in the heart tissues of fatal injury, carbon monoxide (CO) intoxication, sudden cardiac death with positive autopsy (SCD-positive autopsy), and sudden cardiac death with negative autopsy (SCD-negative autopsy) by H&E staining and PicroSirius Red (PSR) staining. The SCD-positive autopsy group presented with severe coronary stenosis, calcification, and fibrotic tissue accumulation, whereas the fatal injury and CO intoxication groups did not show notable pathological changes. SCD-negative autopsy group showed slight histological changes such as interstitial edema, fiber rupture, and patchy hypereosinophilia of cardiomyocytes. Scale bar = 200 μm