Missed acute cardiac ischemia in the ED: limitations of diagnostic testing

High-Risk Chief Complaints I: Chest Pain-The Big Three (an Update)

Nontraumatic chest pain is a frequent concern of emergency department patients, with causes that range from benign to immediately life threatening. Identifying those patients who require immediate/urgent intervention remains challenging and is a high-risk area for emergency medicine physicians where incorrect or delayed diagnosis may lead to significant morbidity and mortality. This article focuses on the 3 most prevalent diagnoses associated with adverse outcomes in patients presenting with nontraumatic chest pain, acute coronary syndrome, thoracic aortic dissection, and pulmonary embolism. Important aspects of clinical evaluation, diagnostic testing, treatment, and disposition and other less common causes of lethal chest pain are also discussed.

Does Concordance with Guideline Triage Recommendations Affect Clinical Care of Patients with Possible Acute Coronary Syndrome?

Background. The Agency for Health Care Policy and Research (AHCPR) Unstable Angina Practice Guideline recommends outpatient management for patients at low risk and admission to a monitored bed for patients at intermediate-high risk of adverse short-term outcomes, but the clinical consequences of adhering to these recommendations are unclear. Methods. This analysis included 7466 adults who presented to the emergency department (ED) with symptoms of possible acute coronary syndrome (ACS) and who participated in 3 prospective clinical effectiveness trials during the period 1993 to 2001. The authors used logistic regression to assess the impact of concordance with guideline triage recommendations on subsequent diagnostic testing, follow-up care, and 30-day mortality and applied propensity score methods to adjust for selection bias. Results. Among low-risk patients (n = 1099), ED discharge was not associated with higher mortality and did not increase the need for emergency care or hospitalization during follow-up (adjusted odds ratio [OR] = 1.0, 95% confidence interval [CI] = 0.63—1.6 for ED revisits); however, 1.7% of discharged low-risk patients had confirmed ACS. Among intermediate- to high-risk patients (n = 6367), admission to a monitored bed was not associated with reduction in 30-day mortality but significantly reduced the need for follow-up ED care (adjusted OR = 0.81, 95% CI = 0.69—0.96). Conclusions. This analysis supports the practice of discharging low-risk ED patients with symptoms of possible ACS but highlights the need to arrange timely follow-up (or to perform additional risk stratification in the ED prior to discharge). It also confirms the benefit of admitting ED patients with intermediate- to high-risk characteristics to a monitored bed.

Role of "Ischemia Modified Albumin" (IMA) in acute coronary syndromes

BACKGROUND

Diagnosis of acute coronary syndrome (ACS) is important, due to the associated very high mortality. Failure to diagnose ACS is a problem both for the patients and the clinicians. Ischemia modified albumin (IMA) has already been licensed by the US Food and Drug Administration for the diagnosis of suspected myocardial ischemia.

METHODS

Patients attending the emergency department (ED) within 6 h after having features of ACS were selected. IMA was done on admission. Blinded to the IMA results patients were fully evaluated and a diagnosis of non-ischemic chest pain (NICP), unstable angina (UA) or myocardial infarction (MI) was made. Later IMA results were correlated in each group.

RESULTS

Mean IMA value was 56.38 ± 23.89 u/ml in NICP group whereas in UA group it was 89.00 ± 7.76 u/ml and MI group was 87.50 ± 9.62 u/ml. This showed a sensitivity of 92% and specificity of 87%. The positive predictive value of the test was 88% and negative predictive value was 94%. In 16 patients an early diagnosis could be made when compared with Trop-T. Of the 89 patients 11 patients died in hospital. The IMA value was compared between this group and the patients who survived. Patients who died had a mean IMA value of 88.5 with a standard deviation of 5.33 whereas in patients who survived the mean value was 78.26 which was not statistically significant.

CONCLUSION

In conclusion the benefit of the test would be to rule out ACS in patients who present early to ED with inconclusive diagnosis.

The efficacy and safety of a chest pain protocol for short stay unit patients: A one year follow-up

BACKGROUND

The Alfred Emergency Short Stay Unit initiated a chest pain protocol for patients presenting with chest pain to risk stratify for acute coronary syndrome (ACS). A 30-day follow-up of patients discharged with low-or-intermediate risk of ACS demonstrated no deaths or ACS.

AIMS

The purpose of this study was to evaluate the long-term safety of the chest pain protocol, a one year follow-up was undertaken.

METHODS

A questionnaire was designed for the one-year follow-up and it was administered via a telephone interview by emergency nurses to document adverse cardiac events and health care utilisation.

RESULTS

From 297 patients, 224 (75%) were contacted 12 months following discharge. There was one death from stroke (0.4%; 95% confidence interval (CI): 0.01-2.5%) and another from an unknown cause. Five patients had been diagnosed with atrial fibrillation (2.2%; 95% CI: 0.7-5.1%), two patients had an acute myocardial infarction (0.9%; 95% CI: 0.03-2.1%) and four were diagnosed with angina (1.8%; 95% CI: 0.9-3.2%). Nearly half (n=103, 46%; 95% CI: 39.5-52.5%) had returned to the emergency department (ED) for various conditions including 42 patients with further chest pain. Ninety-six patients (43%; 95% CI: 39.3-52.7%) had specialist referrals and 124 investigations were performed. Thirty-four patients had cardiology referrals (15%; 95% CI: 10.7-20.5%) and 25 patients had gastroenterology referrals (11%; 95% CI: 7.3-16.0%). Diagnostic cardiac tests were performed on 38 patients: coronary angiography (n=10), 24-hour Holter monitoring (n=17), 24-hour blood pressure (BP) monitoring (n=4), thallium scans (n=5), exercise stress test (n=1) and CT scan (n=1).

CONCLUSION

Patients had a low risk of adverse events 12 months after discharge but substantial continuing health care utilization was observed. Complete assessment by health care professionals prior to discharge may help mitigate representations.

Current role of myeloperoxidase in routine clinical practice

Recognition of inflammation as a critical contributor to atherothrombosis has led to the pursuit of new approaches for the diagnosis and treatment of patients with coronary heart disease. As the intricate relationships between cellular and noncellular participants in the inflammatory aspects of atherogenesis, plaque destabilization and thrombosis have been defined, specific constituents have emerged as potential noninvasive indicators of these processes. Myeloperoxidase is a protein released during degranulation of neutrophils and monocytes. The available experimental and epidemiologic data provide compelling evidence to sustain strong interest in myeloperoxidase as a candidate for clinical application. Nevertheless, additional investigation will be important to fully evaluate myeloperoxidase as a sensitive predictor for myocardial infarction in patients with chest pain.

Current role of ischemia-modified albumin in routine clinical practice

BACKGROUND

Ischemia-modified albumin has been proposed as a useful rule-out marker for the diagnosis of acute coronary syndrome in the emergency department.

OBJECTIVE

To perform a review of ischemia-modified albumin use in the clinical practice.

METHODS

We performed a comprehensive literature search by using electronic bibliographic databases.

CONCLUSION

Although the main limitation of ischemia-modified albumin at present is its low specificity, it may be a useful test to rule out acute coronary syndrome from low to moderate pre-test probability conditions with negative cardiac troponins and a negative ECG.

High-risk chief complaints I: chest pain--the big three

Chest pain is one of the most frequently seen chief complaints in patients presenting to emergency departments, and is considered to be a "high-risk" chief complaint. The differential diagnosis for chest pain is broad, and potential causes range from the benign to the immediately life-threatening. Although many (if not most) emergency department patients with chest pain do not have an immediately life-threatening condition, correct diagnoses can be difficult to make, incorrect diagnoses may lead to catastrophic therapies, and failure to make a timely diagnosis may contribute to significant morbidity and mortality. Several atraumatic "high-risk" causes of chest pain are discussed in this article, including myocardial infarction and ischemia, thoracic aortic dissection, and pulmonary embolism. Also included are brief discussions of tension pneumothorax, esophageal perforation, and cardiac tamponade.

Effects of socioeconomic status on mortality after acute myocardial infarction

PURPOSE

To assess the effects of socioeconomic status on mortality in patients with acute myocardial infarction.

MATERIAL AND METHODS

We studied a retrospective cohort of 5622 patients who presented to a hospital emergency department with an initial episode of acute myocardial infarction between April 1998 and March 2002 in the Province of Alberta, Canada. Our main outcome measure was 1-year all-cause mortality following the index emergency department visit; we used socioeconomic status (measured by neighborhood median household income) as our main predictor after controlling for patient and hospital characteristics and revascularization.

RESULTS

Socioeconomic status profoundly affected the rate of emergency department presentation and the process and outcome of acute myocardial infarction care. In patients belonging to the lowest versus the highest socioeconomic status quartile, the risk of presenting to the emergency department was 72% higher (P <.001); at 1 year, revascularization was lower (36% vs 48%, P <.001), and mortality higher (19.1% vs 9.1%, P <.001). Socioeconomic status was independently associated with 1-year mortality after adjustment for baseline characteristics and 1-year revascularization, and socioeconomic status was especially influential in non-revascularized patients.

CONCLUSIONS

Given the influence of socioeconomic status on mortality after acute myocardial infarction and the key role of revascularization in modulating this relationship, our study has important implications for access to and process of cardiac care.

Noninvasive Imaging Techniques to Aid in the Triage of Patients with Suspected Acute Coronary Syndrome: A Review

The evaluation, treatment, and disposition of patients with symptoms suggestive of acute coronary syndrome (ACS) in the Emergency Department continues to be a clinical challenge. Many patients with suggestive symptoms are admitted to the hospital to rule out a myocardial infarction by serial enzyme tests and EKGs and receive an expedited work-up for ischemia. However, the diagnosis can be difficult, given the wide range of potentially atypical symptoms that can signal ACS, which remains a major clinical risk for patients and a liability risk for emergency physicians. This article reviews imaging technologies such as echocardiography and nuclear perfusion imaging used currently in the diagnosis of ACS and rapidly advancing technologies such as CT and MRI that may be able to visualize calcifications, plaques, occlusions, and infarctions noninvasively in real time. Some noninvasive tests used to complete an ischemia work-up after serial enzyme testing and EKGs, such as exercise EKG, stress echocardiography, and stress perfusion imaging, also are reviewed.

Beckman Access versus the Bayer ACS:180 and the Abbott AxSYM cardiac Troponin-I real-time immunoassays: an observational prospective study

Background

Reliability of cardiac troponin-I assays under real-time conditions has not been previously well studied. Most large published cTnI trials have utilized protocols which required the freezing of serum (or plasma) for delayed batch cTnI analysis. We sought to correlate the presence of the acute ischemic coronary syndrome (AICS) to troponin-I values obtained in real-time by three random-mode analyzer immunoassay systems: the Beckman ACCESS (BA), the Bayer ACS:180 (CC) and the Abbott AxSYM (AX).

Methods

This was an observational prospective study at a university tertiary referral center. Serum from a convenience sampling of telemetry patients was analyzed in real-time for troponin-I by either the BA-CC (Arm-1) or BA-AX (Arm-2) assay pairs. Presence of the AICS was determined retrospectively and then correlated with troponin-I results.

Results

100 patients were enrolled in Arm-1 (38 with AICS) and 94 in Arm-2 (48 with AICS). The BA system produced 51% false positives in Arm-1, 44% in Arm-2, with negative predictive values of 92% and 100% respectively. In Arm-1, the BA and the CC assays had sensitivities of 97% and 63% and specificities of 18% and 87%. In Arm-2, the BA and the AX assays had sensitivities of 100% and 83% and specificities of 11% and 78%.

Conclusions

In real-time analysis, the performance of the AxSYM and ACS:180 assay systems produced more accurate troponin-I results than the ACCESS system.