Inflammation and fibrosis characterize different stages of myocardial remodeling in patients after stereotactic body radiotherapy of ventricular myocardium for recurrent ventricular tachycardia
Abstract
We performed a histological and immunohistochemical analysis of myocardia from 3 patients who un-derwent radiosurgery and died for various reasons 3 months to 9 months after radiotherapy. In Case 1 (death 3 months after radiotherapy) we observed a sharp transition between relatively intact and irradiated regions.
In the myolytic foci, only scattered cardiomyocytes were left and the area was in-filtrated by immune cells. Using immunohistochemistry we detected numerous inflammatory cells in-cluding CD68 + /CD11c + macrophages, CD4 + and CD8 + T-lymphocytes and some scattered CD20 + B-lymphocytes.
Mast cells were diminished in contrast to viable myocardium. In Case 2 and Case 3 (death 6 and 9 months after radiotherapy, respectively) we found mostly fibrosis, infiltration by adipose tissue and foci of calcification.
Inflammatory infiltrates were less pronounced. Our observations are in accor-dance with animal experimental studies and confirm a progress from myolysis to fibrosis.
In addition, we demonstrate a role of pro-inflammatory macrophages in the earlier stages of myocardial remodeling after stereotactic radioablation for ventricular tachycardia.