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Looking for prognostic information in the ST-T segment--is it really worth it?
Peter W Macfarlane1, John Norrie,
1Section of Cardiology and Exercise Medicine, Royal Infirmary, Glasgow, United Kingdom. peter.w.macfarlane@clinmed.gla.ac.uk
Journal of Electrocardiology
|November 10, 2004
Summary
Electrocardiogram (ECG) findings like heart rate and T axis offer limited prognostic value for myocardial infarction risk when considering clinical data. Age and smoking history alone provide comparable predictive power to ECG combined with age.
Area of Science:
- Cardiology
- Preventive Medicine
- Medical Informatics
Background:
- The West of Scotland Coronary Prevention Study (WOSCOPS) involved 6,595 men without prior myocardial infarction.
- Participants were followed for a mean of 4.9 years, with half receiving lipid-lowering drugs and the other half a placebo.
- Baseline electrocardiograms (ECGs) were collected, offering an opportunity to assess ECG morphology as a risk marker.
Purpose of the Study:
- To evaluate the prognostic value of electrocardiographic (ECG) morphology in predicting myocardial infarction.
- To identify specific ECG parameters and clinical factors that predict fatal or non-fatal myocardial infarction.
- To develop a risk score based on significant ECG and clinical predictors.
Main Methods:
- Utilized 12-lead ECGs from the WOSCOPS cohort, processed using the Glasgow Program and automated Minnesota Coding.
- Performed univariate and multivariate logistic regression analyses to identify predictive electrocardiographic and clinical parameters.
- Focused on ST-T variables and QT dispersion, and developed a risk score incorporating significant predictors.
Main Results:
- While many ECG measures showed univariate prognostic value, only heart rate, frontal T axis, and T+ amplitude in lead I remained significant in multivariate analysis including clinical data.
- QT dispersion exceeding 44 ms was associated with increased risk (RR 1.38), but its predictive curve was poor.
- Age and smoking history alone demonstrated prognostic value comparable to ECG measures combined with age.
Conclusions:
- Electrocardiogram variables have limited independent prognostic value for myocardial infarction when considered alongside clinical data.
- Clinical factors such as age and smoking history are strong predictors of cardiovascular events.
- The prognostic utility of ECG findings must be carefully evaluated in the context of other available patient information.