Current issues of ACP Journal Club are published in Annals of Internal Medicine


Diagnosis

Serial ECGs were more sensitive than an initial ECG for diagnosing chest pain

ACP J Club. 1998 Jul-Aug;129:15. doi:10.7326/ACPJC-1998-129-1-015


Source Citation

Fesmire FM, Percy RF, Bardoner JB, Wharton DR, Calhoun FB. Usefulness of automated serial 12-lead ECG monitoring during the initial emergency department evaluation of patients with chest pain. Ann Emerg Med. 1998 Jan;31:3-11.


Abstract

Question

Is automated serial 12-lead electrocardiogram (SECG) monitoring better than an initial 12-lead electrocardiogram (ECG) for detecting acute injury or ischemia in patients presenting to the emergency department and admitted for chest pain?

Design

Blinded assessment of SECG monitoring and initial ECG monitoring to detect acute injury or ischemia.

Setting

The emergency department of a university teaching hospital in the United States.

Patients

1000 adults (mean age 56 y, 61% men, 80% white) presenting with chest pain suspicious for coronary ischemia who were admitted and had ≥ 1 hour of SECG monitoring. Exclusion criteria were recent cocaine use; chest pain in the presence of a tachyarrhythmia or pulmonary edema; or presence of a demand pacemaker.

Description of tests and diagnostic standard

The initial ECG was obtained on presentation. SECG monitoring consisted of ST-segment measurement every 20 seconds, automated SECG readings every 20 minutes, and alarm ECGs during the initial evaluation. Readings were classified as diagnostic (for initial ECG, evidence of acute injury or ischemia; for SECG, evolving or new injury or ischemia) or nondiagnostic. The diagnostic standard was patient discharge diagnosis based on a blinded chart review.

Main outcome measures

Sensitivity and specificity of initial ECG monitoring and SECG monitoring.

Main results

Discharge diagnoses were acute myocardial infarction (n = 204), recent myocardial infarction (n = 18), unstable angina (n = 295), and other diagnoses (n = 483). SECG monitoring was more sensitive than an initial ECG for detecting acute myocardial infarction (P < 0.001) and acute coronary syndromes (P < 0.001) and was more specific for detecting acute coronary syndromes (P < 0.01) (Table).

Conclusion

12-lead automated serial electrocardiogram monitoring was more sensitive than an initial 12-lead electrocardiogram for detecting acute myocardial infarction and acute coronary syndromes in patients with chest pain admitted through the emergency department.

Source of funding: None.

For correspondence: Dr. F.M. Fesmire, University of Tennessee College of Medicine, Post Office Box 4045, Chattanooga, TN 37405, USA. FAX 423-265-4639.


Table. Diagnostic properties of initial electrocardiogram (ECG) and serial ECG (SECG) monitoring for acute myocardial infarction (MI) and acute coronary syndromes (ACSs)

Diagnosis Sensitivity, % (95% CI) Specificity, % (CI) +LR* -LR*
MI using ECG 55.4 (48.6 to 62.2) 94.6 (93.0 to 96.2) 10.3 0.47
MI using SECG 68.1 (61.7 to 74.5) 94.8 (93.3 to 96.4) 13.1 0.34
ACSs using ECG 27.5 (23.6 to 31.3) 97.1 (95.6 to 98.6) 9.5 0.75
ACSs using SECG 34.2 (30.1 to 36.3) 99.4 (98.7 to 100) 57.0 0.66

*+LR = likelihood ratio for presence of disease if the test is positive; -LR = likelihood ratio if the test is negative. Both calculated from data in article.


Commentary

The study by Fesmire and colleagues is the first step in the prospective evaluation of the diagnostic performance of automated SECG in the emergency department. The use of a single ECG for the detection of acute cardiac ischemia gives the clinician only a slice-in-time recording of an ongoing dynamic process reflecting varying degrees of coronary occlusion and the interaction between thrombogenic and thrombolytic factors. SECG monitoring, by prolonging the period of data collection, may allow the immediate and ongoing recognition of recrudescent ST-segment deviation and may thereby improve patient selection for thrombolysis or coronary angioplasty and help assess vessel patency after these interventions.

However, despite the attractiveness of SECG monitoring, its actual effect on care has not yet been shown. The study by Fesmire and colleagues showed modest improvements in sensitivities in the diagnosis of acute myocardial infarction and acute coronary syndromes, which may have been overestimated given the relatively low interobserver reliability for ECG interpretation (89.8%). Standardized computerized waveform measurements in future studies may minimize interobserver variability by supplementing physician ECG interpretation (1).

Despite these and other limitations, such as the exclusion of patients not admitted to the hospital and patients without chest pain, studies such as this one represent an important step in evaluating SECG monitoring. Future large, prospective, randomized studies that include all patients presenting to an emergency department and incorporate bedside clinical information will provide proper validation of this technology for diagnosis and clinical outcome prediction in the emergency department.

Boris E. Coronado, MD
Harry P. Selker, MDTufts University School of MedicineNew England Medical CenterBoston, Massachusetts, USA


Reference

1. Selker HP, Zalenski RJ, Antman EM, et al. Measurement of drug compliance by continuous electronic monitoring: a pilot study in elderly patients discharged from hospital. Ann Emerg Med. 1997;29:13-87.