Serum NT-proBNP levels and histopathological myocardial fibrosis in autopsied cases from a Japanese community: The Hisayama Study

Background: natriuretic peptide is associated with myocardial fibrosis in animal models and among patients with heart disease. However, it remains unclear whether serum N-terminal pro-B-type peptide (NT-proBNP) levels are associated with histopathologically proven myocardial fibrosis among individuals without apparent heart disease. This study aimed to evaluate the association between serum NT-proBNP levels and the histopathologically estimated myocardial fibrotic area in autopsied samples from a community. Methods: we selected 63 cases without apparent heart disease with available data of serum NT-proBNP concentrations within six years before death (average age: 82 years; male: 52%) from autopsied cases in a community, and evaluated the percentage areas of myocardial fibrosis in four cardiac segments from each case (i.e. 252 cardiac segments in total). The association between serum NT-proBNP levels and the percentage area of myocardial fibrosis was estimated using a linear mixed model for repeated measures. Results: serum NT-proBNP levels were positively correlated with myocardial fibrotic area [Pearson's correlation coefficient: r = 0.49 (95% confidence interval: 0.28–0.66), p <0.001]. Serum NT-proBNP levels were significantly associated with the percentage areas of myocardial fibrosis after adjusting for potential confounding factors. There was no evidence of heterogeneity in the association between the subgroups with and without reduced estimated glomerular filtration rate (<60 mL/min/1.73 m²). Conclusions: the present study demonstrated that elevated serum NT-proBNP levels were associated with the histopathologically measured myocardial fibrotic area in autopsied cases from a community. These findings may help clarify the association between elevated serum NT-proBNP levels and myocardial fibrosis and their influence on prognosis.