Elsevier

Annals of Emergency Medicine

Volume 48, Issue 6, December 2006, Pages 666-677.e9
Annals of Emergency Medicine

Cardiology and vascular/original research
The Internet Tracking Registry of Acute Coronary Syndromes (i*trACS): A Multicenter Registry of Patients With Suspicion of Acute Coronary Syndromes Reported Using the Standardized Reporting Guidelines for Emergency Department Chest Pain Studies

https://doi.org/10.1016/j.annemergmed.2006.08.005Get rights and content

Study objective

Observational studies of well-described patient populations presenting to emergency departments (EDs) with suspicion of acute coronary syndrome are necessary to understand the relationships between patients’ signs and symptoms, cardiac risk profile, test results, practice patterns, and outcomes. We describe the methods for data collection and the ED population enrolled in a multicenter registry of patients with chest pain.

Methods

Patients older than 18 years, presenting to one of 8 EDs in the United States or 1 ED in Singapore, and with possible acute coronary syndrome were enrolled in the Internet Tracking Registry of Acute Coronary Syndromes between June 1999 and August 2001. Prospective data, including presenting signs and symptoms, ECG findings, and the ED physician’s initial impression of risk, were systematically collected. Medical record review or daily follow-up was used to obtain cardiac biomarker results, invasive and noninvasive testing, treatments, procedures, and inhospital outcomes. Thirty-day outcomes were determined by telephone follow-up and medical record review.

Results

The registry includes 15,608 patients, with 17,713 visits. Chest pain was the chief complaint in 71% of visits. The ECG was diagnostic of ischemia or infarction in 10.1% and positive cardiac biomarkers were observed in 10% of visits. Forty-three percent of patients were sent home directly from the ED. Of admitted patients, 5% died by 30 days, and 3% had documented coronary artery disease or had undergone percutaneous coronary intervention or coronary artery bypass grafting within 30 days. For patients discharged directly from the ED, 0.4% died or had a documented myocardial infarction within 30 days. Coronary artery bypass graft surgery, percutaneous coronary intervention, or a diagnosis of coronary artery disease was found in 0.5% of discharged patients.

Conclusion

A unique description of undifferentiated ED chest pain patients with suspected acute coronary syndrome is provided. The data set can be used to generate and explore hypotheses to improve understanding of the complex relationships between presentation, treatment, testing, intervention and outcomes.

Introduction

More than 5.5 million patients present to a United States emergency department (ED) with chest pain and other symptoms related to acute coronary syndrome each year.1 Acute coronary syndrome is observed in people of all ages, races, and socioeconomic backgrounds. The clinical presentation of acute coronary syndrome is heterogeneous, varying from ST-segment elevation with positive cardiac biomarker results of myocardial necrosis to the very subtle cases of acute coronary syndrome with no observable ECG changes,2 negative cardiac biomarker results,3 atypical signs and symptoms,4 and a nonspecific medical history.4 This broad spectrum of disease has been extensively researched, yet appropriate evaluation and treatment can remain problematic for individual patients, and the impact of acute coronary syndrome remains enormous. Recently, improvements in medical management and invasive therapeutic options for these patients have resulted in the publication of numerous guidelines for appropriate evaluation and treatment of acute coronary syndrome.5, 6, 7 Despite these expert opinions, guidelines are poorly followed, disparities in outcomes persist, and emergency physicians miss up to 2% of acute myocardial infarctions in patients presenting to EDs.8, 9 To reduce the burden of acute coronary syndrome on patients and providers, delineating the relationship between evaluation, treatment, and outcomes is fundamental.

Randomized controlled trials can demonstrate the effectiveness of therapies or treatment pathways. They cannot help us to completely understand the complex presentations of acute coronary syndrome in the clinical setting. The only feasible method for unraveling the interaction between practice patterns, manners of presentation, patient characteristics, diagnostic testing, therapy, and outcomes in contemporary practice is through observational studies.

To our knowledge, the only inclusive multicenter observational data sets compiled heretofore are those reported by Goldman et al10 and Selker et al,11 which were used to develop risk-stratification protocols for ED chest pain patients. Although inclusive, both data sets commenced more than 15 years ago, when many of today’s guidelines, as well as diagnostic and therapeutic options, did not exist. This limits generalizability to today’s practice of emergency medicine. Further, only limited descriptions of these patient populations are available, providing insufficient information for evaluating generalizability. Guidelines for reporting studies of chest pain patients have recently been developed to assist researchers in satisfying the minimum description of the sample necessary for understanding ED chest pain studies.12 These guidelines offer data definitions and indicate those variables that must be reported to interpret study results in an optimal and generalizable fashion. No multicenter observational cohort study has previously attempted to use these guidelines to describe a large patient population with suspected acute coronary syndrome.

The dearth of more recent observational studies of well-described patient populations presenting to EDs with any suspicion of acute coronary syndrome represents a significant barrier to understanding the relationships between patients, signs and symptoms, practice patterns, and outcomes. There is a fundamental requirement for such a study. This need was recognized by EMCREG in 1999 when several of its member institutions began compiling i*trACS (the Internet Tracking Registry of Acute Coronary Syndromes). Since the registry was closed to enrollment in late 2001, subsets of the data have been used to assess health disparities, explore practice patterns, evaluate relationships between ECG results and cardiac biomarkers, and investigate the utility of diagnostic tests in subgroups such as diabetic patients and patients with heart failure.13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 However, a comprehensive description of the institutions collecting the data, the data collection methods, and of the entire cohort enrolled in the registry has yet to be provided. To facilitate use of the i*trACS database for exploring the complex interactions involved in the ED evaluation and treatment of acute coronary syndrome, we describe the data collection procedures and present a description of the entire spectrum of patients with suspected acute coronary syndrome using the standardized reporting guidelines for chest pain studies.

Section snippets

Study Design

This was a multicenter study using both direct observation and medical record review methods. Institutional review boards or ethics committees approved patient enrollment without informed consent at 8 of the 9 centers; at one center, verbal informed consent was required from the patients before data collection. At this site, no patients were known to have refused participation.

Setting

Eight sites participating in the registry were selected to represent a cross-section of providers in the United States;

Results

Throughout the 3 years, 12,390 patients suspected of having acute coronary syndrome and who had an ECG ordered by the treating physician were enrolled at one of 8 EDs in the United States. An additional 3,008 patients were enrolled in Singapore; data for these patients are available in Appendix E1 (available online at http://www.annemergmed.com). In the United States, there were 14,185 patient visits. Six patients visited the ED 10 or more times, 53 patients visited between 5 and 10 times, 55

Limitations

There are several limitations of this data set that must be accommodated by researchers using the registry. The primary limitation is the potential for bias arising from the sampling method. Although we attempted to sample as completely as possible, patients presenting overnight and on holidays were excluded at some sites. Complete capture during sampling hours is also unlikely; the practicality of obtaining a truly complete sample excluded its possibility. The most likely bias resulting from

Discussion

Several large observational studies are reported in the contemporary literature. The Global Registry of Acute Coronary Events project26 has evaluated such diverse factors as the impact of diabetes and the effectiveness of percutaneous coronary intervention, thrombolytics, and glycoprotein IIb/IIIa receptor inhibitors, as well as describing variations in practice patterns and developing risk prediction models.27, 28, 29, 30, 31 Although providing valuable insights into acute coronary syndrome in

References (35)

  • E.M. Antman et al.

    ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1999 Guidelines for the Management of Patients with Acute Myocardial Infarction)

    J Am Coll Cardiol

    (2004)
  • Clinical policy: critical issues in the evaluation and management of adult patients presenting with suspected acute myocardial infarction or unstable angina

    Ann Emerg Med

    (2000)
  • J.H. Pope et al.

    Missed diagnosis of acute cardiac ischemia in the emergency department

    N Engl J Med

    (2000)
  • L. Goldman et al.

    A computer protocol to predict myocardial infarction in emergency department patients with chest pain

    N Engl J Med

    (1988)
  • H.P. Selker et al.

    A time-insensitive predictive instrument for acute myocardial infarction mortality: a multicenter study

    Med Care

    (1991)
  • J.E. Hollander et al.

    Standardized reporting guidelines for studies evaluating risk stratification of emergency department patients with potential acute coronary syndromes

    Ann Emerg Med

    (2004)
  • B.C. Hiestand et al.

    Insurance status and the treatment of myocardial infarction at academic centers

    Acad Emerg Med

    (2004)
  • Cited by (0)

    Supervising editor: Michael L. Callaham, MD

    Author contributions: The i*trACS project was conceived and designed by CVP, JWH, JEH, JDK, WFP, BT, EKW, and WBG. CVP, VA, DD, JWH, JEH, JDK, S-HL, WFP, BT, EKW, and WBG were responsible for data collection. CJL prepared and analyzed the data, and CJL, CVP, JHH, and WBG drafted the manuscript. All authors provided critical revision of the manuscript for intellectual content. CJL had full access to the data and takes full responsibility for the integrity and analysis of the data. CJL takes responsibility for the paper as a whole.

    Funding and support: The i*trACS project was supported in part by Millenium Pharmaceuticals and Schering-Plough Pharmaceuticals.

    Reprints not available from the authors.

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