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High-risk subgroups of patients with non-Q wave myocardial infarction based on direction and severity of ST segment
S N Willich1, P H Stone, J E Muller
1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
Insights
ST segment deviation direction impacts non-Q wave myocardial infarction (MI) outcomes. ST segment depression indicates smaller infarcts but higher mortality, necessitating close surveillance and potentially aggressive therapy for these patients.
Area of Science:
- Cardiology
- Internal Medicine
Background:
- Non-Q wave myocardial infarction (MI) prognosis can be influenced by initial electrocardiogram (ECG) findings.
- ST segment deviation on admission is a key indicator in acute coronary syndromes.
Purpose of the Study:
- To assess the prognostic significance of ST segment depression versus ST segment elevation on admission in patients with non-Q wave myocardial infarction (MI).
Main Methods:
- Comparison of 97 patients with initial ST segment depression against 207 patients with initial ST segment elevation.
- Analysis of infarct size (creatine kinase MB isoenzyme), left ventricular ejection fraction, in-hospital complications, and 1-year mortality.
Main Results:
- Patients with ST segment depression had smaller infarcts but lower ejection fraction, more complications, and significantly higher 1-year mortality (29% vs 11%).
- An ST segment deviation severity index was not prognostic for ST depression but identified high-risk patients with ST elevation.
Conclusions:
- Non-Q wave MI patients presenting with ST segment depression face a poorer prognosis, despite smaller infarct size.
- Close surveillance and consideration of aggressive therapy are recommended for non-Q wave MI patients with either ST depression or severe ST elevation on admission.
Abstract:
To determine the significance of the direction of ST segment deviation on admission of patients who evolved non-Q wave myocardial infarction (MI), 97 patients with initial ST segment depression were compared to 207 patients with initial ST segment elevation. Patients with ST segment depression developed smaller infarcts than those with ST segment elevation (creatine kinase MB isoenzyme 8.2 vs 13.3 gmEq/m2, p less than 0.002), but had a lower left ventricular ejection fraction on admission (44% vs 51%, p less than 0.001), more in-hospital complications, and a higher cumulative 1-year mortality (29% vs 11%, p less than 0.001) that could be accounted for by an excess of adverse baseline characteristics. Although a severity index (combining magnitude and extent of the initial ST segment deviation) was not useful for discriminating prognosis of patients with non-Q wave MI who presented with ST segment depression, it was useful in identifying a subgroup of patients with ST segment elevation with an adverse prognosis. The poor outcome of patients with non-Q wave MI presenting with either ST segment depression or severe ST segment elevation on admission suggests that patients in these subgroups should receive close surveillance and should possibly be considered for aggressive therapy.