Key result
ST elevation predicts evolving MI in ~84% of chest pain patients vs ST depression.
Why the study?
Accurate early diagnosis of evolving myocardial infarction using electrocardiographic ST segment changes and the impact of prior myocardial infarction on predictive value were uncertain.
Does a history of prior myocardial infarction affect the predictive value of ST segment elevation or depression for diagnosing acute myocardial infarction in patients with chest pain?
Observational (n=100)
No
Does a history of prior myocardial infarction affect the predictive value of ST segment elevation or depression for diagnosing acute myocardial infarction in patients with chest pain?
A history of prior myocardial infarction significantly reduces the positive predictive value of ST segment elevation for acute myocardial infarction due to false-positive acute injury patterns in areas of prior Q wave infarction.
Answers are grounded in this paper and cite their sources.
Prior MI history attenuates ST elevation PPV for acute MI; leaves open refined ECG criteria in observational cohorts.
• Prompt management of patients suffering acute myocardial infarction requires accurate early diagnosis based on the electrocardiogram. To assess the predictive value of ST segment elevation and ST segment depression (both ≥0.1 mV) for the diagnosis of evolving myocardial infarction, we studied 100 consecutive patients admitted to the coronary care unit of The New York Hospital with at least 30 minutes of chest pain. Of 31 patients with ST segment elevation, 26 patients (84%) evolved myocardial infarction (positive test results for serum creatine phosphokinase—MB isoenzyme fraction), while only 13 (48%) of 27 patients with ST segment depression had myocardial infarctions. Among patients with ST segment elevations with a history of prior myocardial infarction, only five (50%) of ten evolved myocardial infarction, compared with 21 of 21 with no prior infarction. False-positive diagnoses of acute injury were due to ST elevation in the area of prior Q wave infarction. Prior myocardial infarction did not alter the lower predictive value of ST segment depression for evolving infarction. We conclude that patients presenting with chest pain and ST segment elevation have approximately twice the likelihood of myocardial infarction than patients with ST segment depression; incorporation of historic information regarding prior myocardial infarction can improve the predictive value of ST segment elevations to 100% but does not improve prediction with ST segment depressions. (Arch Intern Med1987;147:257-261)
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D. H. Miller (1987) conducted an observational in chest pain (n=100). ST segment elevation (≥0.1 mV) vs. ST segment depression (≥0.1 mV) was evaluated on Evolving myocardial infarction (positive test results for serum creatine phosphokinase-MB isoenzyme fraction). ST segment elevation predicted evolving myocardial infarction in 84% of patients with chest pain compared to 48% for ST segment depression, improving to 100% in those without prior infarction.
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