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Unexplained gradual-onset Q wave patterns. A case series from the Framingham Study
J M Murabito1, M G Larson, S T Lin
1Section of General Internal Medicine, Boston University School of Medicine, Massachusetts 01701, USA.
Journal of Electrocardiology
|October 1, 1995
Summary
Unexplained Q waves on electrocardiograms (ECGs) indicate a lower risk of myocardial infarction or coronary death compared to unrecognized myocardial infarction. Differentiating Q wave types is crucial for accurate prognosis.
Area of Science:
- Cardiology
- Preventive Medicine
- Epidemiology
Background:
- Routine electrocardiograms (ECGs) can reveal Q wave patterns.
- The prognostic significance of unexplained (gradual-onset) Q waves requires clarification.
Purpose of the Study:
- To determine the prognosis associated with unexplained Q wave patterns detected on routine ECGs.
- To compare the risk of adverse cardiovascular outcomes between unexplained Q waves, unrecognized myocardial infarction, and referent subjects.
Main Methods:
- Analysis of original cohort members from the Framingham Study with biennial ECGs.
- Independent and serial ECG readings to identify Q wave patterns and myocardial infarction.
- Proportional hazards modeling to assess outcome risks.
Main Results:
- Subjects with unexplained Q wave patterns had significantly lower risk (38%) of myocardial infarction or coronary death compared to unrecognized myocardial infarction.
- A trend towards lower overall mortality was observed in subjects with unexplained Q waves.
- Risks for cardiovascular events and mortality were similar between unexplained Q waves and referent subjects after adjustments.
Conclusions:
- Differentiating unexplained Q waves from unrecognized myocardial infarction via serial ECG comparison is critical.
- Unexplained Q wave patterns have a more favorable prognosis than unrecognized myocardial infarction.