Use of initial ST-segment deviation for prediction of final electrocardiographic size of acute myocardial infarcts
H R Aldrich1, N B Wagner, J Boswick
1Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Insights
New formulas predict final heart attack size using initial ECG ST-segment deviation. This aids early treatment decisions for acute myocardial infarction (AMI) when reperfusion therapy is considered.
Area of Science:
- Cardiology
- Medical Diagnostics
Background:
- Early assessment of myocardial infarction (MI) size is crucial for treatment decisions.
- Thrombolytic therapy for acute myocardial infarction (AMI) requires rapid evaluation of jeopardized myocardium.
Purpose of the Study:
- To develop predictive formulas for final AMI size based on initial electrocardiogram (ECG) findings.
- To assess the correlation between ST-segment deviation (ST delta) and infarct size in patients without reperfusion therapy.
Main Methods:
- Formulas were derived from 68 anterior and 80 inferior AMI patients.
- Quantified ST delta extent using lead count, sum of ST delta, and location-specific ST delta.
- Compared ECG-derived measures with final AMI size estimated by Selvester QRS score.
Main Results:
- Developed predictive formulas for anterior and inferior AMI size based on ST delta.
- Anterior AMI formula: 3[1.5 (number leads ST increases) - 0.4].
- Inferior AMI formula: 3[0.6 (sigma ST increases II, III, aVF) + 2.0].
Conclusions:
- Quantitative ST delta measurements on admission ECG predict final QRS-estimated AMI size.
- These formulas may assist in evaluating the effectiveness of acute reperfusion therapies.
- ECG-based prediction offers a rapid method for assessing infarct size in acute settings.
Abstract:
The decision to administer thrombolytic therapy for limitation of acute myocardial infarction (AMI) size must occur when only the history, physical examination and 12-lead electrocardiogram of a patient are available. A method that could quickly assess the amount of jeopardized myocardium would greatly aid the physician. This study developed formulas from 68 anterior and 80 inferior AMI patients using the extent of initial ST-segment deviation (ST delta) to predict the final AMI size estimated by the Selvester QRS score in a population not receiving reperfusion therapy. Inclusion required: initial anterior or inferior AMI; admission electrocardiogram less than or equal to 8 hours after the onset of symptoms with evidence of epicardial injury; elevated creatine kinase-MB; a predischarge electrocardiogram taken greater than or equal to 72 hours after admission; and no AMI extension before the predischarge electrocardiogram. The extent of epicardial injury was quantified by counting the number of leads with greater than or equal to 0.1 mm ST delta, by the sum (sigma) of ST delta in all leads and by the sigma ST delta in the lead groups associated with each AMI location. These results were compared to the AMI size estimated from the predischarge electrocardiogram. Univariable and multivariable analyses generated these formulas for AMI size: anterior = 3[1.5 (number leads ST increases) - 0.4]; inferior = 3[0.6 (sigma ST increases II, III, aVF) + 2.0]. Thus, formulas based on quantitative measurements of ST delta on the admission electrocardiogram are predictive of final QRS-estimated AMI size, and may be useful in determining the efficacy of acute reperfusion therapy.
