ɪn nˈaɪntiːnhˈʌndɹɪd fˈɪfti sˈɛvən blˈækʃˈæfɚ pɹəpˈoʊzd ɐ jˈuːnɪtˌɛɹi ɛksplɐnˈeɪʃən ðæt stɹˈɛs ɔnðə vˈɛntɹɪkəl, ʌv ˌɛni kˈaɪnd, mˈeɪ tɹˈɪɡɚ ðɪ ˌɛndoʊkˈɑːɹdɪəl ɹɪˈækʃən, sˌoʊ ðæt ˈɔːl ˌiːˌɛfˈiː kʊd biː θˈɔːt ʌv æz sˈɛkəndɚɹi.
In 1957 Black-Schaffer proposed a unitary explanation that stress on the ventricle, of any kind, may trigger the endocardial reaction, so that all EFE could be thought of as secondary.