The relationship between 1-year mortality and infarct location in patients with non-Q wave myocardial infarction

Abstract

The association between 1-year mortality and infarct location was evaluated in 544 patients with acute non-Q wave myocardial infarction. Infarcts were anterior (alone or including other locations) in 51.1% ( n = 278) of cases, localizable but not anterior 29.6% ( n = 161) of the time, and nonlocalizable in 19.3% ( n = 105) of patients. One-year actuarial mortality (73 deaths) was 16.9% in the anterior group, 13.3% in the nonanterior group, and 6.8% in nonlocalizable patients ( p = 0.037). Anterior and localizable nonanterior mortality were similar ( p = 0.367). However, there were differences when mixed location infarcts were excluded. Mortality in the inferior infarction only group (2.8%, n = 36) was less than in the lateral infarction only group (16.8%, n = 79, p = 0.041) and almost significantly less than in the anterior only group (15.1%, n = 62, p = 0.064). The positive prognosis in the inferior infarction only group may be associated with the low rate of ST depression among these patients compared with those with other infarct locations ( p < 0.0001). Mortality among localizable infarcts (15.5%) was greater than among those that were nonlocalizable (6.8%, p = 0.021). Despite the low overall risk of the nonlocalizable infarcts, 41.9% ( n = 44) of these patients developed at least one important risk factor while in hospital. We conclude that among patients with relatively small non-Q wave myocardial infarction: (1) anterior mortality is similar to localizable nonanterior mortality; (2) inferior only infarcts have a better prognosis than infarcts with other non-mixed locations; (3) infarct localizability implies increased risk; and (4) nonlocalizable infarcts define a heterogeneous group among which a substantial proportion will develop in-hospital risk factors that are associated with decreased survival.