Author + information
- aDivision of Cardiology, Massachusetts General Hospital, Boston, Massachusetts
- bBaim Institute for Clinical Research, Boston, Massachusetts
- cDepartment of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- ↵∗Address for correspondence:
Dr. James L. Januzzi Jr., Division of Cardiology, Massachusetts General Hospital, 32 Fruit Street, Yawkey 5B, Boston, Massachusetts 02114.
Approximately 7 million patients present to the emergency department (ED) each year with chest pain, at an estimated cost of $5 billion (1). Although a cardiovascular cause may be present in up to 20% of patients presenting with chest discomfort, only 5.5% of these patients have an acute life-threatening condition, whereas more than one-half of the huge number of patients presenting with chest discomfort receive a diagnosis of noncardiac pain (2); the great majority of these patients are low risk. Physicians must therefore decipher which patients should be hospitalized for treatment from those patients with lesser urgent conditions who might be discharged safely from the ED. Failure to accurately sort out these patients may have significant ramifications because patients with acute myocardial infarction (MI) mistakenly discharged from the ED have almost double the risk of mortality compared with those who are hospitalized (3). On the other hand, prolonged assessment of all patients who present to the ED with chest pain is costly and associated with ED overcrowding, and needless admissions add to costs of care. As such, the principal objective in the evaluation of chest discomfort in the ED is rapid, but accurate, diagnosis and risk stratification.
History, physical examination, electrocardiogram, and serial measurement of troponin form the cornerstone of assessment for patients with suspected MI. However, if these are unrevealing, the clinician is faced with the challenging decision whether to admit or discharge the patient.
The acceptable risk at which a patient can be discharged from the hospital without further testing is a matter of debate and, in clinical practice, oftentimes dependent on personal comfort. Kline et al. (4) demonstrated that a 2% miss rate should be acceptable on the basis of the risk of harm from further testing exceeding the benefit from confirming acute coronary syndrome (ACS) at this cutoff. However, a survey of 1,029 emergency medicine physicians found that a major adverse cardiac event (MACE) miss rate of <1% to be tolerable among the majority of respondents (5). What options exist to help achieve the optimal balance of speed and accuracy?
Refinement in assay technology has led to the development of high-sensitivity troponin (hsTn) assays that may identify acute MI as early as 1 to 2 h from coronary ischemia onset and provide useful risk stratification; such tests remain limited by context: many patients presenting very early after pain onset may yet have a low hsTn concentration, whereas a significant percentage of patients may have unambiguously elevated hsTn but without acute MI. Thus, clinical contextualization is needed to improve performance of these assays. In an effort to achieve this goal, several risk scores have been explored, including the modified History, Electrocardiogram, Age, Risk factors and Troponin (HEART) score, the Emergency Department Assessment of Chest pain Score (EDACS), and the simplified EDACS score. Though each is helpful, it remains somewhat uncertain how incorporation of hsTn into these algorithms affects their performances.
In this issue of the Journal, Mark et al. (6) retrospectively evaluated performance of several risk scores for chest pain evaluation in a large study sample of patients seen in the Kaiser Permanente health system. To do so, the authors incorporated troponin concentrations down to the limit of quantitation; although the assay used was not an hsTn method, this cutoff provides sensitivity comparable to the hsTn assays soon to be launched in the United States. The primary endpoint was major adverse cardiac events (MACE) (MI, cardiogenic shock, fatal events) by 60 days.
The results of the study suggest this approach further refined the ability to exclude risk, with reclassification yields ranging between 3.4% and 3.9% while maintaining similar negative predictive values (range 99.49% to 99.55%; p = 0.27) (6). The original EDACS score performed the best, identifying the largest proportion of patients as low risk (60.6%, 95% confidence interval [CI]: 60.3% to 60.9%), compared with the modified HEART (51.8%, 95% CI: 51.6% to 52.1%) and the simplified EDACS (48.1%, 95% CI: 47.8% to 48.3%; p < 0.0001), without compromising prediction of MACE (6).
A strength of the study is the cohort size (118,822 patients), whereas limitations include the retrospective design and the use of conventional troponin assays, as opposed to hsTn; nonetheless, this study affirms the value of very low troponin concentrations to exclude risk, whether the assay is of high sensitivity or not, and further emphasizes the importance of adding clinical color to the laboratory result to obtain best performance.
In addition to the modified scores presented by Mark et al. (6), clinicians now have several clinical scores at their disposal when evaluating chest pain in the ED (Table 1). Although further validation of these scores in large prospective randomized trials is warranted, their use with hsTn (or very low conventional troponin concentrations as in the study by Mark et al.) is promising. For example, a prospective study compared the ability of 5 established risk scores (modified Goldman, TIMI [Thrombolysis In Myocardial Infarction], GRACE [Global Registry of Acute Coronary Events], HEART, and the Vancouver Chest Pain Rule), used in combination with a single hsTnT (using a cutoff of 14 ng/l) or hsTnI (using a cutoff of 26.2 ng/l), to identify low-risk patients who may be suitable for early discharge (7). Two risk scores (TIMI 0 or ≤1 and modified Goldman) in combination with hsTnI and 2 risk scores (TIMI 0 and HEART ≤3) combined with hsTnI identified >30% of patients as low risk, and achieved negative predictive values of >99.5% and sensitivities of >98% for acute MI at 30 days (7). Thus, the use of risk scores together with hsTn appears to be the path forward to unlock the ability to more confidently exclude risk in patients presenting with chest discomfort and suspected acute MI. Future studies should focus on how such scores should be used to decide on utilization of other modalities for evaluating suspected coronary ischemia, such as computed tomography angiography.
With rising costs and increasing pressure to reduce hospitalizations, a clear tension is present; on the one hand, we cannot admit every patient to evaluate chest discomfort, but on the other hand, missing a high-risk cardiac diagnosis is not acceptable. In this modern health care environment, ED physicians are confronted with a most challenging task. With several available clinical risk scores with significant ability to exclude MI while simultaneously identifying substantial numbers of lower-risk patients suitable for early discharge, we may finally have a suitable gatekeeper to assist the pressurized decision making that occurs in the ED setting.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Januzzi is supported in part by the Hutter Family Professorship in Cardiology; has received grant support from Siemens, Singulex, and Prevencio; has received consulting income from Roche Diagnostics, Critical Diagnostics, Philips, and Novartis; and participates in clinical endpoint committees/data safety monitoring boards for Novartis, Amgen, Janssen, and Boehringer Ingelheim. Dr. McCarthy has reported that he has no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation
- ↵Centers for Disease Control and Prevention, Ambulatory and Hospital Care Statistics Branch. National Hospital Ambulatory Medical Care Survey: 2010 Emergency Department Summary Tables. Available at: http://www.cdc.gov/nchs/data/ahcd/nhamcs_emergency/2010_ed_web_tables.pdf. Accessed November 21, 2017.
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