Myocardial Fibrosis in End-Stage HCM

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In hearts of ES-HCM undergoing heart transplantation the amount of myocardial fibrosis was very marked; there was a clear base-to-apex gradient, with the apex more involved by fibrosis. The most represented pattern was midwall, while subendocardium and subepicardium were never exclusively involved. The LV’s inferior and anterior walls as well as the entire septum were maximally involved, whereas the inferolateral wall was relatively spared. Replacement fibrosis was the predominant type and it was marked and typical of advanced stage of the disease. There was a good correlation between fibrosis quantitatively detected by CMR and by histometric analysis. Our study focused on myocardial fibrosis and on its pathogenetic role. Indeed fibrosis represents one of the primary phenotypic expressions of HCM and is not necessarily a time related complication. In particular, a recent study showed that a LGE extent ≥15% of the LV mass confer a >2-fold risk of SCD and a LGE amount ≥20% conveys a >3-fold increase in risk of ES-HCM evolution. Therefore, research in this field and the understanding of molecular mechanisms which are the basis of the excessive and pathological fibrosis production could lead cardiovascular science to discover new specific therapies, targeted to block or reduce fibrosis development. A clear example could be the development of new monoclonal antibodies that block TGF-beta or proteins and genes involved in fibrosis production

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