Special Contribution—National Heart Attack Alert Program Report
Diagnosing acute cardiac ischemia in the emergency department: A systematic review of the accuracy and clinical effect of current technologies,☆☆,

Presented in part at the Society for General Internal Medicine Conference, Boston, MA, May 2000, and the American Association of Clinical Chemists, Arlington, VA, May 2000.
https://doi.org/10.1067/mem.2001.114903Get rights and content

Abstract

Study Objective: Acute cardiac ischemia (ACI) encompasses the diagnoses of unstable angina pectoris and acute myocardial infarction (AMI). Accurate diagnosis and triage of patients with ACI in the emergency department should increase survival for these patients and reduce unnecessary hospital admissions. Methods: We conducted a systematic review of the English-language literature published between 1966 and December 1998 on the accuracy and clinical effect of diagnostic technologies for ACI. We evaluated prospective and retrospective studies of adult patients who presented to the ED with symptoms suggesting ACI. Outcomes were diagnostic performance (test sensitivity and specificity) and measures of clinical effect. Meta-analyses were performed when appropriate. A decision and cost-effectiveness analysis was conducted that investigated various diagnostic strategies used in the diagnosis of ACI in the ED. Results: We screened 6,667 abstracts, reviewed 407 full articles, and included 106 articles articles in the main analysis. Single measurements of biomarkers at presentation to the ED have low sensitivity for AMI, although they have high specificity. Serial measurements greatly increase the sensitivity for AMI while maintaining their excellent specificity. Diagnostic technologies to evaluate ACI in selected populations, such as electrocardiography, sestamibi perfusion imaging, and stress ECG, may have very good to excellent sensitivity; however, they have not been sufficiently studied. The Goldman Chest Pain Protocol has good sensitivity (about 90%) for AMI but has not been shown to result in any differences in hospitalization rate, length of stay, or estimated costs in the single clinical effect study performed. Its applicability to patients with unstable angina pectoris has not been evaluated. The use of an Acute Cardiac Ischemia-Time-Insensitive Predictive Instrument led to the appropriate triage of 97% of patients with ACI presenting to the ED and reduced unnecessary hospitalizations. Conclusion: Many of the current technologies remain underevaluated, especially regarding their clinical effect. The extent to which combinations of tests may provide better accuracy than any single test needs further study. [Lau J, Ioannidis JPA, Balk EM, Milch C, Terrin N, Chew PW, Salem D. Diagnosing acute cardiac ischemia in the emergency department: a systematic review of the accuracy and clinical effect of current technologies. Ann Emerg Med. May 2001;37:453-460.]

Introduction

Acute myocardial infarction (AMI) is the leading cause of death in the United States and many developed countries. As such, investigating the causes, progression, and treatment of AMI continues to be a research priority. Recently, the emphasis has been on acute cardiac ischemia (ACI), which includes AMI and unstable angina pectoris (UAP), because research has shown that early diagnosis and treatment of UAP is beneficial and may prevent myocardial infarction and death. In 1991, the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health initiated the National Heart Attack Alert Program (NHAAP) to study the issues related to rapid recognition and response to patients with signs and symptoms of ACI in emergency department settings, the point at which most of these patients enter the health care system. This ongoing effort brings together scientists, clinicians, and NHLBI staff with a coordinating committee that includes representatives of 40 professional organizations (http://www.nhlbi.nih.gov/about/nhaap/index.htm ).

In 1994, the NHAAP Working Group on Evaluation of Technologies for Identifying Acute Cardiac Ischemia in the Emergency Department was formed. The Working Group reviewed all technologies for diagnosing ACI in the ED. The assessments of these technologies in actual use in the ED and the nature, extent, and quality of the evidence on which the assessments were based are presented in the final 1997 report.1

Because of the introduction of new diagnostic tests and the rapid increase in the number of publications evaluating the performance of various diagnostic technologies, in 1998, the Agency for Healthcare Research and Quality (formerly the Agency for Health Care Policy and Research), working as a partner with the NHLBI NHAAP, contracted with the New England Medical Center’s Evidence-based Practice Center to update the 1997 NHAAP report. The Evidence-based Practice Center was charged with evaluating the evidence on those diagnostic technologies published since October 1994. We summarize the results of our report2 in this series of articles.

Section snippets

Materials and methods

The 1997 report contains no details about the individual studies reviewed and no quantitative estimates of diagnostic performance or clinical effect. In addition, although the medical literature was used as the basis of evidence, the report’s recommendations were based on consensus without the aid of a quantitative framework, such as meta-analyses, decision analyses, and cost-effectiveness analyses. We addressed these issues in the updated report.

We conducted a systematic search of the

Results

The MEDLINE search identified 6,667 titles. About a third of these titles were published after 1993, indicating an increasing rate of research publications on this topic in recent years. From these abstracts, 407 full articles were retrieved for review, 106 of which were included in the analysis.

The numerous studies included in the current analysis used a large variety of entry criteria. About half of the studies analyzed were of category II populations, and about a third were in category III.

Discussion

ACI is a continuum of clinical states that range from reduced myocardial perfusion with exercise to infarction of myocardial tissues. Identifying only patients with AMI misses a large number of ED patients with UAP, who are also at high risk of cardiac events.

About 15% of patients with unrecognized UAP evaluated in the ED have an AMI within 2 months of admission.13, 14, 15, 16 Early recognition and treatment of AMI could reduce the amount of myocardial tissue damage, improve cardiac function

Future research

Despite some progress in refining these technologies since the 1997 Working Group report, the overall research effort in this area needs to be improved. In particular, the needs described below should be addressed.

Although more than 45 relevant studies have been published since 1994 on this topic, many of the diagnostic technologies for ACI remain underevaluated. Studies of newer biomarkers, such as P-selectin and fatty acid–binding proteins, are also needed. Imaging technologies, such as

Acknowledgements

We thank the members of the NHAAP Technology Working Group for their input and the peer reviewers of the evidence report for their invaluable comments. We also thank Thomas Lang for his editorial assistance.

References (18)

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Dr. Ioannidis is now at the Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece.

☆☆

This study was conducted by the New England Medical Center Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (formerly, Agency for Health Care Policy and Research), contract No. 290-97-0019, Rockville, MD.

Reprints not available from the authors.

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