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Should the electrocardiogram be used to guide therapy for patients with left bundle-branch block and suspected
M G Shlipak1, W L Lyons, A S Go
1Veterans Affairs Medical Center, Department of Medicine, University of California, San Francisco 94121, USA.
Insights
An electrocardiogram (ECG) algorithm does not reliably predict myocardial infarction (MI) in patients with left bundle-branch block (LBBB). Thrombolytic therapy should be considered for all LBBB patients with symptoms suggestive of MI.
Area of Science:
- Cardiology
- Emergency Medicine
- Diagnostic Algorithms
Background:
- An electrocardiogram (ECG) algorithm was developed to predict myocardial infarction (MI) in patients with left bundle-branch block (LBBB).
- The clinical impact and diagnostic utility of this ECG algorithm remain largely unknown.
Purpose of the Study:
- To evaluate the diagnostic test characteristics of the ECG algorithm for MI in patients with LBBB.
- To assess the clinical utility of the ECG algorithm in guiding treatment decisions for suspected MI.
Main Methods:
- Retrospective cohort study involving patients with LBBB and symptoms suggestive of MI.
- Application of a specific ECG algorithm to predict MI.
- Decision analysis comparing thrombolysis guided by the algorithm versus standard care.
Main Results:
- The ECG algorithm demonstrated low sensitivity (10%) in identifying MI.
- None of the assessed ECG findings effectively differentiated MI from other diagnoses in this cohort.
- Decision analysis indicated that universal thrombolysis for LBBB patients with chest pain resulted in better survival outcomes compared to using the ECG algorithm as a screening tool.
Conclusions:
- The ECG algorithm is an unreliable predictor of MI in patients with LBBB presenting with acute cardiopulmonary symptoms.
- Acute thrombolytic therapy should be strongly considered for all patients with LBBB experiencing symptoms consistent with MI.
Context:
Recently, an algorithm based on the electrocardiogram (ECG) was reported to predict myocardial infarction (MI) in patients with left bundle-branch block (LBBB), but the clinical impact of this testing strategy is unknown.
Objective:
To determine the diagnostic test characteristics and clinical utility of this ECG algorithm for patients with suspected MI.
Design:
Retrospective cohort study to which an algorithm was applied, followed by decision analysis regarding thrombolysis made with or without the algorithm.
Setting:
University emergency department, 1994 through 1997.
Patients:
Eighty-three patients with LBBB who presented 103 times with symptoms suggestive of MI.
Main Outcome Measures:
Myocardial infarction determined by serial cardiac enzyme analyses and stroke-free survival.
Results:
Of 9 ECG findings assessed, none effectively distinguished the 30% of patients with MI from those with other diagnoses. The ECG algorithm indicated positive findings in only 3% of presentations and had a sensitivity of 10% (95% confidence interval, 2%-26%). The decision analysis showed that among 1000 patients with LBBB and chest pain, 929 would survive without major stroke if all received thrombolysis compared with 918 if the ECG algorithm was used as a screening test.
Conclusions:
The ECG is a poor predictor of MI in a community-based cohort of patients with LBBB and acute cardiopulmonary symptoms. Acute thrombolytic therapy should be considered for all patients with LBBB who have symptoms consistent with MI.
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