ˌiːˌɛfˈiː ɪz kˈæɹɪktɚɹˌaɪzd baɪ ɐ θˈɪkənɪŋ ʌvðɪ ˈɪnɚmˌoʊst lˈaɪnɪŋ ʌvðə hˈɑːɹt tʃˈeɪmbɚz ðɪ ˌɛndoʊkˈɑːɹdiəm dˈuː tʊ ɐn ˈɪŋkɹiːs ɪnðɪ ɐmˈaʊnt ʌv səpˈoːɹɾɪŋ kənˈɛktɪv tˈɪʃuː ænd ᵻlˈæstɪk fˈaɪbɚz.
EFE is characterized by a thickening of the innermost lining of the heart chambers (the endocardium) due to an increase in the amount of supporting connective tissue and elastic fibres.