Endomyocardial fibrosis: pathological and molecular findings of surgically resected ventricular endomyocardium

Abstract

Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy of unknown etiology prevalent in tropical regions affecting the inflow tract and apex of one or both ventricles, which show fibrous thickening of the endocardium and adjacent myocardium. Surgical treatment is recommended for patients in functional classes III or IV (New York Heart Association). The gross and histological features of the heart have been comprehensively studied in autopsies, but studies in surgical samples are still lacking. Histological and immunohistochemical features of EMF in surgical samples collected from 32 patients were described and correlated with clinical data. Polymerase chain reaction (PCR) and reverse transcription-PCR, performed on formalin fixed endomyocardial samples, were used retrospectively to detect genomes of certain cardiotropic viruses and Toxoplasma gondii. Ventricular endocardium was thickened by superficial acellular hyaline collagen fibers type I and III, with predominance of the former type. Besides fibrosis, a chronic inflammatory process and an anomalous lymphatic rich vascular pattern were observed in the deep endocardium, connected to the terminal coronary circulation of the myocardium, which might be an important pathological finding concerning EMF pathogenesis. Molecular analysis of the endomyocardium revealed high incidence of cardiotropic infective agents (6/12, 50%); however, their role in the disease pathogenesis is still controversial.

Isolated right ventricular endomyocardial fibrosis in a young male with chronic myeloid leukemia (RCD code: III-3F.2)

“…The etiology of the disease is unknown, however it has been associated with a number of factors including tropical climate, helminthic infections and eosinophilia, certain cardiotropic viruses, ingestion of certain foods like cassava, combination of magnesium deficiency and high levels of cerium in the body [8][9][10][11]. No such factors were found in our patient.…”

Tropical Endomyocardial Fibrosis

“…67,68 The disease afflicts individuals in rural settings, which are also endemic for malaria, but again, geographic distributions of EMF and malaria have not matched in a coherent fashion to allow causal links to be drawn. 30,[69][70][71][72][73][74][75][76][77][78][79] Furthermore, malaria has never been described as being associated with myocardial or endocardial damage. 80 The concept of molecular mimicry, similar to rheumatic heart disease, 72,73 has also been proposed as a mechanism but without compelling evidence.…”

Endomyocardial Fibrosis Associated With Apical Calcification and High Uptake on Myocardial Gallium-67 Scintigraphy

“…This disease is associated with eosinophilia or parasitic infection, suggesting that inflammation is a critical step in the progression. 6 To date, however, the early phase of EMF has not been well described, because most patients do not exhibit symptoms until they are at a late stage in the clinical course. 7 Late gadolinium enhancement MRI is useful for detecting subendocardial fibrosis, but not for detecting active inflammation.…”