PATHOPHYSIOLOGY AND NATURAL HISTORY MYOCARDIAL INFARCTION Prognostic significance of electrocardiographic site of infarction after correction for enzymatic size of infarction

To assess whether the site of myocardial infarction is an independent prognostic indicator, the outcome of patients with anterior myocardial infarction was compared with that of patients with inferior infarction. A consecutive series of patients who had suffered their first myocardial infarction was analyzed (398 with anterior and 391 with inferior infarction). Patients with anterior myocardial infarction had a higher 1 year mortality than those with inferior infarction (18.3% vs 10.5%, p = .002). When patients were matched for infarct size determined by peak creatine kinase (CK) level expressed as a multiple of the upper limit of normal, those with anterior myocardial infarction tended to have a higher 1 year mortality than those with inferior infarction for all subgroups of peak CK. Early mortality (day 1 to 28 after myocardial infarction) was greater in the anterior than in the inferior myocardial infarction group (10% vs 6.4%, p = .03); this was most significant when peak CK was greater than four times normal (12.4% vs 7.0%, p = .04). Late mortality was also higher in the anterior (8.4% vs 4. 1%, p = .04) than the inferior infarction group and this was most significant when peak CK was less than two times normal (15.2% vs 0%, p = .02) or greater than eight times normal (10.6% vs 4.1%, p = .04). Multivariate analysis with proportional-hazards regression confirmed the prognostic significance of location of infarction independent of peak CK level. Thus, infarct location was found to be a predictor of prognosis that is independent of infarct size based on peak CK levels. Circulation 73, No. 5, 885-891, 1986.! THE PROGNOSIS of patients with anterior myocardial infarction is significantly worse than that of patients with inferior myocardial infarction. '-5 Anterior infarction is associated with more myocardial damage than inferior infarction.5' 6 It remains unclear whether this difference in survival is due to the site or the size of myocardial infarction. Goldberg et al.7 concluded that the poorer prognosis for patients with anterior myocardial infarction was probably related to the extent of myocardial damage rather than the location of the injury. Strauss et al.' demonstrated a poorer prognosis (both early and late) for patients with anterior than for those with inferior infarction of similar size. However, they found no From the Department of Cardiovascular Medicine, Sir Charles Gairdner Hospital, and the Research Unit in Epidemiology and Preventive Medicine, University of Western Australia, Nedlands, Western Australia. Address for correspondence: Dr. Mark E. Hands, Department of Cardiovascular Medicine, Queen Elizabeth II Medical Centre, Verdun St., Nedlands, Westem Australia 6009. Received April 25, 1985; revision accepted Jan. 23, 1986. Vol. 73, No. 5, May 1986 difference in the extent of infarction with either location of infarction, a finding that differs from other reports.5'6 Thanavaro et al.5 concluded that peak enzyme level and the location of the infarct each have independent influence on in-hospital prognosis of patients with myocardial infarction. In this study we sought to clarify the influence of site of myocardial infarction on both early and late mortality. To assess the independent contribution of location of infarction to prognosis, the patients were grouped according to peak serum enzyme levels, since these reflect the extent of myocardial necrosis.9`3 Since previous studies""t1 have documented that prognosis is not only dependent on the size of the most recent infarction, but also on whether the patient has had previous infarctions, we prospectively studied the outcome of patients experiencing their first myocardial infarction. Methods Patient population. All patients less than 70 years of age who were admitted to the Sir Charles Gairdner Hospital Coro885 by gest on A ril 6, 2017 http://ciajournals.org/ D ow nladed from