Mitral incompetence complicating acute myocardial infarction.

Mitral incompetence appearing in connexion with acute coronary heart disease without papillary muscle rupture has not received much attention until recently. Castex (1933) presented eight patients with electrocardiographic findings of inferior myocardial infarction and with an apical murmur of mitral incompetence as a distinct clinical syndrome. Nezlin and Shamesova (1951) paid attention to the occurrence of mitral incompetence in association with extensive myocardial infarction involving papillary muscles. Froment et al. (1955) observed mitral incompetence in 48 of 189 patients with myocardial infarction, and pointed out that it was usually associated with an inferior wall lesion and that it could occur without an increase in heart size. Their series, however, was not presented in detail. During the past few years mitral incompetence developing in patients with acute myocardial infarction has been a subject of increasing interest. In some small series of patients with this complication the occurrence of mitral incompetence without papillary muscle rupture has been ascribed to "papillary muscle dysfunction" caused by infarc-tion or ischemia (Burch, De Pasquale, and Phillips, 1963; Phillips, Burch, and De Pasquale, 1963; Orlando et al., 1964; Bashour, 1965). The murmur arising from this kind of mitral incompetence has been described by some of these investigators as pansystolic (Orlando et al., 1964; Bashour, 1965), and by others as ejection in type (Burch et al., 1963; Phillips et al., 1963; Segal and Likoff, 1964). In a few cases the presence of mitral incompetence has been confirmed by angiocardiographic studies (Mazzitello, 1964; Holloway, Whalen, and McIntosh, 1965; Tavel, Campbell, and Zimmer, 1965). When experimental coronary artery ligation or papillary muscle damage has been produced in dogs,