Pathological study on the relationship between nucleic acid oxidative stress and heart failure with preserved ejection fraction in patients aged over 85 years

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Objective: To investigate the level of nucleic acid oxidation in myocardial tissue of patients aged over 85 with heart failure with preserved ejection fraction (HFpEF) and the correlation with myocardial amyloid deposition. Methods: This was a retrospective case-control study. Data of patients≥85 years old who underwent systematic pathological autopsy in Beijing Hospital from 2003 to 2017 were retrospectively collected. Twenty-six patients were included in the HFpEF group and 13 age-and sex-matched patients who had not been diagnosed with heart failure and died of non-cardiovascular diseases served as the control group. The left ventricular myocardium slices of both groups were semi-quantitatively analyzed using immunohistochemical staining of 8-oxidized guanine riboside (8-oxo-G) and 8-oxidized guanine deoxyriboside (8-oxo-dG) to evaluate the oxidation of RNA and DNA in cardiomyocytes. Using the median of the mean absorbance value of 8-oxo-G immunohistochemical staining as the cut-off value, patients were divided into high-absorbance group and low-absorbance group. Congo red staining was used to compare myocardial amyloid deposition between the two groups. Results: The mean age of patients in HFpEF group was (91.8±3.7) years, 24 (92.3%) were males. The mean age of patients in control group was (91.7±3.7) years old, 11 (84.6%) were males. The median mean optical absorbance value of 8-oxo-G immunohistochemical staining of myocardium was significantly higher in HFpEF patients than in control group (0.313 8 (0.302 2, 0.340 6) vs. 0.289 2 (0.276 7, 0.299 4), Z=-3.245, P=0.001). The median mean absorbance value of 8-oxo-dG immunohistochemical staining of myocardial tissue was similar between the two groups (0.300 0 (0.290 0, 0.322 5) vs. 0.300 0 (0.290 0, 0.320 0), Z=-0.454, P=0.661). Proportion of patients with moderate and severe cardiac amyloid deposition was significantly higher in the high-absorbance group than in the low-absorbance group ((85.0%, 17/20) vs. (31.6%, 6/19), P=0.001). Conclusion: The RNA oxidation degree of myocardium in HFpEF patients is higher than that in elderly people without heart failure. Degree of myocardial amyloid deposits is higher in patients with high levels of RNA oxidation.