Histomorphometric Evaluation of Myocardial Tissue Zones in Patients With Persistent Hypokalaemia

Background: Persistent hypokalaemia influences cardiac structure and function, but its zonal effect on myocardial remodeling is not definite. This study quantitatively examined myocardial tissue zones in chronic hypokalaemia, to build a schematic model of myocardial remodeling. Methods: This a cross-sectional analytical study (March to September 2022) was carried out in Department of Histopathology including Sixty postmortem myocardial samples from patients with chronic hypokalemia (serum K+ <3.0 mmol/L) were examined. Tissue samples from the endocardial, mid-myocardial and epicardial areas were stained and histomorphometric parameters were determined. Zonal comparisons were done by the method of repeated measures analysis of variance, correlation was determined between serum levels of potassium by Pearson correlation (p < 0.05 is considered as significant). Results: Zonal differences were found to be significant in myocyte diameter (F = 6.42, p = 0.002), nuclear density (F = 5.91, p = 0.004), interstitial fibrosis (F = 5.87, p = 0.004) and vascular density (F = 4.72, p = 0.011). The endocardial zone had the highest interstitial fibrosis (28.6 ± 6.2%), smallest diameter of myocytes (12.6 ± 2.1 um), lowest nuclear density (185 ± 22 nuclei/mm2) and vascular density (9.8 ± 2.1 vessels/mm2) compared to the mid-myocardial and epicardial zones. Lower serum potassium levels correlated with increased fibrosis (r = -0.52, p < 0.001), decreased myocyte diameter (r = +0.46, p = 0.003), decreased nuclear density (r = +0.39, p = 0.007) and decreased vascular density (r = +0.41, p = 0.005). Conclusion: Chronic hypokalaemia results in zone-specific histomorphometric remodeling of myocardial tissue, which is mainly manifested as endocardial fibrosis, decreased vascularity, and depletion of nuclei.