PROGNOSTIC
VALUE OF A NORMAL OR NONSPECIFIC INITIAL ELECTROCARDIOGRAM IN ACUTE MYOCARDIAL
INFARCTION.
Welch
RD, et al. JAMA 2001 Oct 24-31;286(16):1977-84.
CONTEXT:
Although previous studies have suggested that normal and nonspecific initial
electrocardiograms (ECGs) are associated with a favorable prognosis for
patients with acute myocardial infarction (AMI), their independent predictive
value for mortality has not been examined.
OBJECTIVE:
To compare in-hospital mortality among patients with AMI who have normal or
nonspecific initial ECGs with that of patients who have diagnostic ECGs.
DESIGN,
SETTING, AND PATIENTS: Multihospital observational study in which 391 208
patients with AMI met the study criteria between June 1994 and June 2000 and
had ECGs that were normal (n = 30 759), nonspecific (n = 137 574), or
diagnostic (n = 222 875; defined as ST-segment elevation or depression and/or
left bundle-branch block). A logistic regression model was constructed using a
propensity score for ECG findings and data on demographics, medical history,
diagnostic procedures, and therapy to determine the independent prognostic
value of a normal or nonspecific initial ECG.
MAIN
OUTCOME MEASURES: In-hospital mortality; composite outcome of in-hospital death
and life-threatening adverse events. RESULTS: In-hospital mortality rates were
5.7%, 8.7%, and 11.5% while the rates of the composite of mortality and
life-threatening adverse events were 19.2%, 27.5%, and 34.9% for the normal,
nonspecific, and diagnostic ECG groups, respectively. After adjusting for other
predictor variables, the odds of mortality for the normal ECG group was 0.59
(95% confidence interval [CI], 0.56-0.63; P<.001) and for the nonspecific
group was 0.70 (95% CI, 0.68-0.72; P<.001), compared with the diagnostic ECG
group.
CONCLUSION:
In this large cohort of patients with AMI, patients presenting with normal or
nonspecific ECGs did have lower in-hospital mortality rates than those of
patients with diagnostic ECGs, yet the absolute rates were still unexpectedly
high.
COMMENTS:
The authors, from the National Registry of Myocardial Infarction, noted that
patients with an initially normal ECG were less likely to get ASA and
beta-blockers, which may explain their higher than expected mortality rate. There
is no good reason to withhold these therapies short of a history of
anaphylaxis, active bleeding (for ASA), hypotension or bradycardia (for
beta-blocker).