Influence of the site of myocardial infarction on mortality rate

In consecutive patients hospitalized with acute myocardial infarction, infarct location according to routine electrocardiogram is of minor importance for the outcome

Most studies have suggested that patients with anterior myocardial infarction have an adverse prognosis compared with patients with inferior infarction. The objective of this study was to compare the mortality and morbidity in anterior versus inferior acute myocardial infarction (AMI) during 1 year in a consecutive series of patients hospitalized with AMI. All patients fulfilling the criteria for AMI who were admitted to a single hospital during 21 months (n = 921) participated in the study. Patients with anterior infarction (n = 312) had a 1-year mortality rate of 26% versus a rate of 24% for patients with inferior infarction (n = 269) (p > 0.2). The corresponding figures for patients with no previous infarction who developed Q waves were 27 and 21%, respectively (p > 0.2). Reinfarction, thromboembolic events, and other aspects of morbidity during long-term follow-up appeared with similar frequency in the two groups. Thus, in a nonselected group of patients admitted to a single hospital because of AMI, the prognosis was found to be similar among patients with inferior and those with anterior infarction. In the subset of patients with a first myocardial infarction who developed Q waves, there was a trend indicating higher mortality in anterior infarction.

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

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 less than 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic significance of location and type of myocardial infarction: independent adverse outcome associated with anterior location

To determine the relative prognostic significance of location (anterior or inferior) and type (Q wave or non-Q wave) of infarction, the hospital course and follow-up outcome (mean duration 30.8 months) of 471 patients with a first infarction were analyzed. Analyses were performed grouping the patients according to infarct location (anterior, n = 253; inferior, n = 218), infarct type (Q wave, n = 323; non-Q wave, n = 148), and both location and type (inferior non-Q wave, n = 85; inferior Q wave, n = 133; anterior non-Q wave, n = 63; and anterior Q wave, n = 190). Patients with anterior infarction had a substantially worse in-hospital and follow-up clinical course compared with those with inferior infarction, evidenced by a larger infarct size (21.2 versus 14.9 g Eq/m2 creatine kinase, MB fraction [MB CK], p less than 0.001), lower admission left ventricular ejection fraction (38.1 versus 55.3%, p less than 0.001) and higher incidence of heart failure (40.7 versus 14.7%, p less than 0.001), serious ventricular ectopic activity (70.2 versus 58.9%, p less than 0.05), in-hospital death (11.9 versus 2.8%, p less than 0.001) and total cumulative cardiac mortality (27 versus 11%, p less than 0.001). Patients with Q wave infarction similarly experienced a worse in-hospital course compared with patients with non-Q wave infarction, evidenced by a larger infarct size (20.7 versus 12.7 MB CK g Eq/m2, p less than 0.001), lower admission left ventricular ejection fraction (43.7 versus 50.6%, p less than 0.001), and a higher incidence of heart failure (31.9 versus 21.6%, p less than 0.05) and in-hospital death (9.3 versus 4.1% p less than 0.05). However, there was no increased rate of reinfarction or mortality in hospital survivors with non-Q wave infarction compared with those with Q wave infarction, and total cardiac mortality was similar (16 versus 21%, p = NS). To evaluate the role of infarct location and type independent of infarct size, patients were grouped according to quartile of infarct size, and outcome was reanalyzed within each group. Patients with anterior infarction demonstrated a lower left ventricular ejection fraction on admission and after 10 days than did patients with inferior infarction, even after adjustment for infarct size, as well as a higher incidence of congestive heart failure and cumulative cardiac mortality.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Survival after hospital discharge in matched populations with inferior or anterior myocardial infarction

Prognostic differences between patients with anterior or inferior myocardial infarction are often related to such variables as previous infarction or the size of the myocardial infarct. We examined the determinants of mortality in 997 hospital survivors of acute Q wave infarction (anterior in 449, inferior in 548) who, although not preselected, were well matched with respect to age, sex and prior infarction or congestive heart failure. Additionally, there was no significant difference in peak serum creatine kinase (CK) between the groups with anterior and inferior infarction (1,459 +/- 1,004 versus 1,357 +/- 1,036). Among the patients with anterior infarction who died during the 1 year follow-up period, 56% died in the first 60 days after hospital discharge compared with 18% of those without inferior infarction (p less than 0.01). Survival curves then became nearly identical at 3 months, and remained so until 1 year when the total mortality rate was 10% for the anterior and 7% for the inferior infarction group (p = NS). Variables associated with heart failure during the hospital phase were more prevalent in anterior infarction, but rales above the scapulae during the hospital stay (p less than 0.0001) and ventricular gallop at the time of discharge (p less than 0.0001) were the top two predictors of 1 year mortality by both univariate and multivariate analysis in inferior infarction. Age (p less than 0.0001) and peripheral edema (p less than 0.0001) were the strongest predictors of mortality in anterior infarction. Previous infarction, although just as common in the group with anterior infarction, was present at 1 year in 48% of nonsurvivors of the group with inferior infarction compared with only 19% of survivors (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

The prognosis of anterior myocardial infarction revisited: a community-wide study

A study was carried out in metropolitan Baltimore in which the short- and long-term prognosis of 655 patients with anterior myocardial infarction (MI) was compared with that of 520 patients with inferior/posterior MI. The study was performed on a community-wide basis in two time periods before the clinical introduction and widespread use of beta-blockade therapy. After simultaneous adjustment for several socio-demographic and clinical variables, the in-hospital case fatality rate was greater for patients with anterior (27.5%) than for those with inferior/posterior MI (22.9%) (p less than 0.05). Similarly, for those discharged alive from the hospital and followed up for as long as 10 years, patients with infarction of the anterior wall had a significantly poorer long-term survival than that of patients with infarction of the inferior/posterior wall (p less than 0.05). These results suggest that closer surveillance should be directed at patients with anterior myocardial infarction, both during the acute phase and after hospital discharge.

Peracute and acute death from ischaemic heart disease within 4 days of onset of symptoms

Post-mortem examination was made of 136 patients who died of ischaemic heart disease from within a few minutes to 4 days after the onset to symptoms. Acute myocardial infarction was detected by means of the histochemistry of dehydrogenases in 102 cases (75%); in 34 cases(25%) no infarction was found, but the presence of coronary obstruction together with clinical symptoms justified the diagnosis of acute coronary insufficiency. Fifty-six of the infarctions occurred within 2--3 h after the onset of ischaemia, 24 within 4--5 h, 12 within 6--24 h, and 10 within 1--4 days. The chances of recovery increased if the patients survived for 24 h. The period of 5 h after the onset of ischaemia appeared especially important; 80 of 102 patients with acute myocardial infarction died during that period. Thirty-one of 34 patients with acute coronary insufficiency and 60 of 102 patients with acute myocardial infarction died peracutely, i.e. within a few minutes to 2 h after the onset of symptoms. In the patients of the latter group the onset of symptoms must have been delayed, otherwise none of these patients could have appeared in the category of peracute death. This delay was more obvious in the patients with acute myocardial infarction localized in the area supplied by the left descending artery. The occurrence of peracute deaths could not be correlated witha particular localization of area of infarction. The causes of coronary obstructions and the role of dynamic disturbances of coronary perfusion in the pathogenesis of coronary insufficiency and myocardial infarction and discussed.