Should the electrocardiogram be used to guide therapy for patients with left bundle-branch block and suspected myocardial infarction?
BACKGROUND
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.


METHODS
Retrospective cohort study to which an algorithm was applied, followed by decision analysis regarding thrombolysis made with or without the algorithm.


METHODS
University emergency department, 1994 through 1997.


METHODS
Eighty-three patients with LBBB who presented 103 times with symptoms suggestive of MI.


METHODS
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.
Veterans Affairs Medical Center, Department of Medicine, University of California, San Francisco 94121, USA.
M G
MG
Shlipak
W L
WL
Lyons
A S
AS
Go
T M
TM
Chou
G T
GT
Evans
W S
WS
Browner
D000465:Algorithms; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000628:therapy; D003661:Decision Support Techniques; D004562:Electrocardiography / Q000706:statistics & numerical data*; D004636:Emergency Service, Hospital; D006785:Hospitals, University; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000628:therapy; D011336:Probability; D012189:Retrospective Studies; D012495:San Francisco; D012680:Sensitivity and Specificity; D015912:Thrombolytic Therapy