Myofibrillolysis and fibrosis predicts myocardial insufficiency

Introduction
Cardiocyte myofibrillolysis and interstitial fibrosis belong to histopathological changes in cardiomyopathies, leading to heart failure.

Aim
To evaluate these changes in apical resection during left ventricular assist device (LVAD) implantation.

Material and methods
The studied group consisted of 40 patients with cardiomyopathy, and apical samples excised during left ventricular assist device implantation were studied (CM/VAD group, mean: 48.1 ±10 y/o). A control group consisted of 6 apical samples from healthy heart graft donors (mean: 29 ±2.3 years old). Area fraction (AF) was calculated for: fibrosis, cardiocytes with myofibrillolysis (MFL), non-myofibrillolytic cardiocytes (non-MFL).

Results
Single lymphocytes were seen in 18 (45%) cases in the CM/VAD group. Cardiomyopathy grade evaluated semiquantitatively in CM/VAD was: slight (25% of a group), moderate (35.5%), advanced (35.5%). CM/VAD cases showed nearly ten times higher fibrosis than the control group. The MFL cells occupied nearly a five times larger area in CM/VAD than in the control group, whereas non-MFL cells were found in the control group, as a predominant pattern. The linear regression calculated between fibrosis AF and types of cardiocytes indicated the depletion of cardiomyocytes with fibrosis increase. The control group presented insignificant dependency between fibrosis and MFL cells, suggesting the lack of replacement fibrosis. Significant negative dependence between fibrosis and non-MFL cardiocytes suggested remodeling in controls. Correlation analysis showed a strong relation between depletion of normal cardiocytes and progression of fibrosis.

Conclusions
Progression of cardiomyopathy and fibrosis depends on the loss of cardiocytes rather than degeneration of these cells.