Study objective:
To determine whether information from a prior electrocardiogram (ECG) improves diagnostic accuracy in the emergency department
(ED) evaluation of patients with acute chest pain.
Design:Analysis of prospectively collected data from a cohort study.
Setting:Emergency departments of four community and three university hospitals.
Patients:5,673 patients aged ≥30 years who presented to the EDs of participating hospitals for evaluation of acute chest pain, including
772 (14%) with acute myocardial infarction (AMI).
Measurements and main results:After adjusting for clinical characteristics, no significant difference was found in the sensitivities of admission to the
hospital or to the coronary care unit (CCU) between AMI patients with and without prior ECGs available for review. However,
non-AMI patients with prior ECGs available for review were more likely to avoid CCU admission than were non-AMI patients without
prior ECGs. This improvement in specificity was most marked in the 2,024 patients whose current ED ECGs had changes consistent
with ischemia or infarction: when a prior ECG was available, non-AMI patients were more than twice as likely to be discharged
(26% vs. 12%) and about 1.5 times as likely to avoid CCU admission (39% vs. 27%) (both p<0.0001). Admission rates of AMI patients
with and without prior ECGs were similar.
Conclusion:When the current ECG is consistent with ischemia or infarction, the availability of a prior ECG for comparison to determine
whether the ECG changes are old or new improves diagnostic accuracy and triage decisions by reducing the admission of patients
without AMI or acute ischemic heart disease (increased specificity) without reducing the admission of patients with these
diagnoses (unchanged sensitivity).
Key words chest pain - myocardial infarction - electrocardiography - diagnosis
Received from Brigham and Women’s Hospital, Harvard Medical School, and Harvard School of Public Health, Boston, Massachusetts;
Yale-New Haven Hospital and Yale University School of Medicine, New Haven, Connecticut; University of Cincinnati Hospital
and University of Cincinnati, Cincinnati, Ohio; Danbury Hospital, Danbury, Connecticut; Milford Hospital, Milford, Connecticut;
St. Mary’s Hospital, Waterbury, Connecticut; and William Beaumont Hospital, Royal Oak, Michigan.
Supported in part by grants from the John A. Hartford Foundation, New York, New York (83102-2H) and from the Robert Wood Johnson
Foundation, Princeton, New Jersey (12543) Dr. Lee is the recipient of a Public Health Service Clinical Investigator Award
(HL01594-05) from the National Heart, Lung, and Blood Institute. Dr. Rouan was a Teaching and Research Scholar of the American
College of Physicians and was supported in part by a grant to the Training Program in Clinical Effectiveness from the W. K.
Kellogg Foundation.