Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. First ECG in chest pain

Symptoms Predictive of Acute Myocardial Infarction in the Troponin Era: Analysis From the TRAPID-AMI Study

The TRAPID-AMI (High Sensitivity Cardiac Troponin T assay for rapid Rule-out of Acute Myocardial Infarction) study evaluated a rapid "rule-out" acute myocardial infarction (AMI). We evaluated what symptoms were associated with AMI as part of a substudy of TRAPID-AMI. There were 1282 patients evaluated from 12 centers in Europe, the United States of America, and Australia from 2011 to 2013. Multiple symptom variables were prospectively obtained and evaluated for association with the final diagnosis of AMI. Multivariate logistic regression analysis was done, and odds ratios (OR) were calculated. There were 213/1282 (17%) AMIs. Four independent predictors for the diagnosis of AMI were identified: radiation to right arm or shoulder [OR = 3.0; confidence interval (CI): 1.8-5.0], chest pressure (OR = 2.5; CI: 1.3-4.6), worsened by physical activity (OR = 1.7; CI: 1.2-2.5), and radiation to left arm or shoulder (OR = 1.7; CI: 1.1-2.4). In the entire group, 131 (10%) had radiation to right arm or shoulder, 897 (70%) had chest pressure, 385 (30%) worsened with physical activity, and 448 (35%) had radiation to left arm or shoulder. Duration of symptoms was not predictive of AMI. There were no symptoms predictive of non-AMI. Relationship between AMI size and symptoms was also studied. For 213 AMI patients, cardiac troponins I values were divided into 4 quartiles. Symptoms including pulling chest pain, supramammillary right location, and right arm/shoulder radiation were significantly more likely to occur in patients with larger AMIs. In a large multicenter trial, only 4 symptoms were associated with the diagnosis of AMI, and no symptoms that were associated with a non-AMI diagnosis.

Utility of the History and Physical Examination in the Detection of Acute Coronary Syndromes in Emergency Department Patients

Chest pain accounts for approximately 6% of all emergency department (ED) visits and is the most common reason for emergency hospital admission. One of the most serious diagnoses emergency physicians must consider is acute coronary syndrome (ACS). This is both common and serious, as ischemic heart disease remains the single biggest cause of death in the western world. The history and physical examination are cornerstones of our diagnostic approach in this patient group. Their importance is emphasized in guidelines, but there is little evidence to support their supposed association. The purpose of this article was to summarize the findings of recent investigations regarding the ability of various components of the history and physical examination to identify which patients presenting to the ED with chest pain require further investigation for possible ACS. Previous studies have consistently identified a number of factors that increase the probability of ACS. These include radiation of the pain, aggravation of the pain by exertion, vomiting, and diaphoresis. Traditional cardiac risk factors identified by the Framingham Heart Study are of limited diagnostic utility in the ED. Clinician gestalt has very low predictive ability, even in patients with a non-diagnostic electrocardiogram (ECG), and gestalt does not seem to be enhanced appreciably by clinical experience. The history and physical alone are unable to reduce a patient's risk of ACS to a generally acceptable level (<1%). Ultimately, our review of the evidence clearly demonstrates that "atypical" symptoms cannot rule out ACS, while "typical" symptoms cannot rule it in. Therefore, if a patient has symptoms that are compatible with ACS and an alternative cause cannot be identified, clinicians must strongly consider the need for further investigation with ECG and troponin measurement.

Sweating: A Specific Predictor of ST-Segment Elevation Myocardial Infarction Among the Symptoms of Acute Coronary Syndrome: Sweating In Myocardial Infarction (SWIMI) Study Group

BACKGROUND

Today, cardiologists seek to minimize time from symptom onset to interventional treatment for the most favorable results.

HYPOTHESIS

In the acute coronary syndrome (ACS) symptom complex, sweating can differentiate ST-segment elevation myocardial infarction (STEMI) from non-ST-segment elevation ACS (NSTE-ACS) during early hours of infarction.

METHODS

This single-center, prospective, observational study compared symptoms of STEMI and NSTE-ACS patients admitted from August 2012 to July 2014.

RESULTS

Of 12 913 patients, 90.56% met ACS criteria. Among these, 22.51% had STEMI. Typical angina was the most common symptom (83.82%). On stepwise multiple regression, sweating (odds ratio: 97.06, 95% confidence interval [CI]: 82.16-114.14, P < 0.0001) and typical angina (odds ratio: 2.72, 95% CI: 2.18-3.38, P < 0.001) had significant association with STEMI. For diagnosis of STEMI, positive likelihood ratio (LR) and positive predictive value (PPV) were highest for typical angina with sweating (LR: 11.17, 95% CI: 10.31-12.1; PPV: 76.09, 95% CI: 74.37-77.75), followed by sweating with atypical angina (LR: 3.6, 95% CI: 3.07-4.21; PPV: 50.61, 95% CI: 46.45-54.76), typical angina (LR: 1.05, 95% CI: 1.03-1.07; PPV: 22.97, 95% CI: 22.11-23.84), and atypical angina (LR: 0.77, 95% CI: 0.69-0.87; PPV: 18.09, 95% CI: 16.32-19.97). C statistic values of 0.859 for typical angina with sweating and 0.519 for typical angina alone reflected high discriminatory value of sweating for STEMI prediction.

CONCLUSIONS

Presence of sweating with ACS symptoms predicts probability of STEMI, even before clinical confirmation. Sweating in association with typical or atypical angina is a much better predictor of STEMI than NSTE-ACS.

A new score for the diagnosis of acute coronary syndrome in acute chest pain with non-diagnostic ECG and normal troponin

BACKGROUND

Acute coronary syndrome (ACS) represents a difficult diagnostic challenge in patients with undifferentiated chest pain. There is a need for a valid clinical score to improve diagnostic accuracy.

OBJECTIVES

To compare the performance of a model combining the Thrombolysis in Myocardial Infarction (TIMI) score and a score describing chest pain (ACS diagnostic score: ACSD score) with that of both scores alone in the diagnosis of ACS in ED patients with chest pain associated with a non-diagnostic ECG and normal troponin.

METHODS

In this observational cohort study, we enrolled 809 patients admitted to a chest pain unit with normal ECG and normal troponin. They were prospectively evaluated in order to calculate TIMI score, chest pain characteristics score and ACSD score. Diagnosis of ACS was the primary outcome and defined on the basis of 2 cardiologists after reviewing the patient medical records and follow-up data. Mortality and major cardiovascular events were followed for 1 month for patients discharged directly from ED. Discriminative power of scores was evaluated by the area under the ROC curve.

RESULTS

ACS was confirmed in 90 patients (11.1%). The area under the ROC curve for ACSD score was 0.85 (95% CI 0.80 to 0.90) compared with 0.74 (95% CI 0.67 to 0.81) for TIMI and 0.79 (95% CI 0.74 to 0.84) for chest pain characteristics score. A threshold value of 9 appeared to optimise sensitivity (92%) and negative predictive value (99%) without excessively compromising specificity (62%) and positive predictive value (23%).

CONCLUSIONS

The ACSD score showed a good discrimination performance and an excellent negative predictive value which allows safely ruling out ACS in ED patients with undifferentiated chest pain. Our findings should be validated in a larger multicentre study.

Myocardial infarction false alarm: initial electrocardiogram and cardiac enzymes

OBJECTIVE

The objectives of this study were to determine the incidence of a myocardial infarction "false alarm" and evaluate the efficacy of the initial electrocardiogram and cardiac enzymes in diagnosing myocardial infarction in Malaysia.

METHODS

We recruited patients who were admitted with suspected myocardial infarction from June to August 2008. The medical records of these patients were reviewed for the initial electrocardiogram, initial cardiac enzyme levels (creatinine kinase-MB and troponin T), and the final diagnosis upon discharge. The subjects were stratified into 2 groups: true myocardial infarction, and false alarm.

RESULTS

125 patients were enrolled in this study. Following admission and further evaluation, the diagnosis was revised from myocardial infarction to other medical conditions in 48 (38.4%) patients. The sensitivity and specificity of the initial ischemic electrocardiographic changes were 54.5% and 70.8%, respectively. Raised cardiac enzymes had a sensitivity of 44.3% and specificity of 95.8%.

CONCLUSION

A significant proportion of patients in Malaysia are admitted with a false-alarm myocardial infarction. The efficacy of the electrocardiogram in diagnosing myocardial infarction in Malaysia was comparable to the findings of Western studies, but the cardiac enzymes had a much lower sensitivity.

The relationship between chest pain duration and the incidence of acute myocardial infarction among patients with acute chest pain

OBJECTIVE

Eight to ten million individuals are evaluated for chest pain (CP) in Emergency Departments (ED) in the United States each year. CP characteristics are an important factor used to help determine a diagnosis. We studied the relationship between the duration of CP and the diagnosis of acute myocardial infarction (AMI) in patients evaluated in the ED.

METHODS

The study population consisted of a sub-group analysis of a previously published study. The survey population consisted of 1024 consecutive encounters of patients who were evaluated for possible ACS in the ED of Henry Ford Hospital between January and May of 1999, CP duration could be obtained in 426 who were included in this analysis.

RESULTS

Of the 426 patients included in the study, 38 (8.9%) had a final diagnosis of AMI, with a median CP duration of 120 minutes (interquartile range, 30-240 minutes), compared with 40 minutes (interquartile range, 6-180 minutes) in patients without AMI (p =0.003). In patients with CP duration less than 5 minutes, there were no AMIs and no deaths at 30 days. There were 10 patients dead at 30 days, with a median CP duration of 180 minutes (interquartile range, 120-1440 minutes) compared to 40 minutes (interquartile range, 10-180 minutes) in patients alive at 30 days (p = 0.011). A longer CP duration and ST depression of 1 mm of less were independently associated with a final diagnosis of AMI.

CONCLUSION

Patients with AMI have longer duration of CP than those without AMI; patients with CP of short duration, less than 5 minutes, are unlikely to have AMI and have a good prognosis at 30 days.

Copeptin: a new marker in cardiology

Copeptin, the C-terminal part of the prohormone of vasopressin (AVP), is released together with AVP in stoichiometric concentrations reflecting an individual's stress level. Copeptin has come to be regarded as an important marker for identifying high-risk patients and predicting outcomes in a variety of diseases. It improves the clinical value of commonly used biomarkers and the tools of risk stratification. Elevated AVP activation and higher copeptin concentrations have been previously described in acute systemic disorders. However, the field that could benefit the most from the introduction of copeptin measurements into practice is that of cardiovascular disease. Determination of copeptin level emerges as a fast and reliable method for differential diagnosis, especially in acute coronary syndromes. A particular role in the diagnosis of acute myocardial infarction (AMI) is attributed to the combination of copeptin and troponin. According to available sources, such a combination allows AMI to be ruled out with very high sensitivity and negative predictive value. Moreover, elevated copeptin levels correlate with a worse prognosis and a higher risk of adverse events after AMI, especially in patients who develop heart failure. Some authors suggest that copeptin might be valuable in defining the moment of the introduction of treatment and its monitoring in high-risk patients. The introduction of copeptin into clinical practice might also provide a benefit on a larger scale by suggesting changes in the allocation of financial resources within the health system. Although very promising, further larger trials are required in order to assess the clinical benefits of copeptin in everyday practice and patient care.

A multicentre analysis of troponin use in clinical practice

BACKGROUND

The role of troponin quantification in evaluation of patients with suspected acute coronary syndrome is established, but with cost implications. Emerging high-sensitivity troponin and novel multi-marker assays herald further resource implications.

AIMS

The objective of this study was to quantify recent trends in troponin usage and costs in a cross-section of hospitals.

METHODS

A cross-sectional survey seeking data on troponin usage and costs from six tertiary referral, public access teaching hospitals for consecutive years between 2003 and 2009 was carried out.

RESULTS

A median annual increase in the volume of troponin assays requested was identified in all six hospitals, with an average median annual increase of 6.9 % across hospitals (interquartile range 3.4, 10.1 %). This annual increase was not accompanied by a corresponding increase in volume of patients presenting to the Emergency Department (ED) with chest pain. The majority (44-67 %) of troponin requests originated in the ED of hospitals. The median annual spend on troponins per hospital was <euro>115,612 (interquartile range <euro>80,452, <euro>140,918). An analysis of results of assays performed in one centre found that the majority (91 %) of troponin assays performed were in the normal range.

CONCLUSIONS

An annual increase in troponin requests without a corresponding increase in patient activity raises the possibility of increasingly indiscriminate troponin testing. The cumulative direct and indirect costs of inappropriate testing are significant. Corrective strategies are necessary to improve patient selection and testing protocols, particularly in the advent of the high-sensitivity troponin assays and novel multi-marker strategies.

Evaluation of acute chest pain in the emergency department: "triple rule-out" computed tomography angiography

Triage of patients with acute, potentially life-threatening chest pain is one of the most important issues currently facing physicians in the emergency department. Appropriate evaluation of these patients begins with a skilled assessment of the individual patient's presenting symptoms and a careful review of his or her history and physical examination, often followed by serial recording of electrocardiograms and measurement of serum biochemical markers such as troponin and d-dimer. Stress testing, often accompanied by rest and stress myocardial perfusion imaging or echocardiography, and other diagnostic testing such as radionuclide lung scanning and invasive angiography may be required. A rapid, accurate, and cost-effective approach for the evaluation of emergency department patients with chest pain is needed. Development of newer generations of multidetector computed tomographic (MDCT) scanners, which are capable not only of performing high-quality noninvasive coronary angiography, but also concurrent aortic and pulmonary angiography, has led to increased use of MDCT for the so-called "triple rule out." MDCT is used for the detection of 3 of the most common life-threatening causes of chest pain-coronary artery disease, acute aortic syndrome, and pulmonary emboli. While triple rule-out protocol can be very useful and potentially cost effective when used appropriately, concern has risen regarding the overuse of this technology, which could expose patients to unnecessary radiation and iodinated contrast. The triple rule-out protocol is most appropriate for patients who present with acute chest pain, but are judged to have low to intermediate increased risk for acute coronary syndrome, and whose chest pain symptoms might also be attributed to acute pathologic conditions of the aorta or pulmonary arteries. MDCT should not be used as a routine screening procedure. Continued technical improvements in acquisition speed and spatial resolution of computed tomography images, and development of more efficient image reconstruction algorithms which reduce patient exposure to radiation and contrast, may result in increased popularity of MDCT for "triple rule-out."

A timely diagnosis of myocardial infarction

The diagnosis of acute myocardial infarction currently rests on the measurement of troponin, a biomarker of myocardial necrosis. Unfortunately, the current generation troponin assays detect troponin only 6-9 h after symptom onset. This can lead to a delay in diagnosis and also excessive resource utilization when triaging patients who, ultimately, have noncardiac causes of acute chest pain. For these reasons, there has been extensive research interest in biomarkers that can detect and rule out myocardial infarction early after symptom onset. These include markers of myocardial injury, such as myoglobin, heart-type fatty acid binding protein, glycogen phosphorylase BB; hemostatic markers, such as D-dimer; and finally, inflammatory markers, such as matrix metalloproteinase 9. Recently, highly sensitive troponin assays have reported an early sensitivity for myocardial infarction of greater than 95%, although at a cost of reduced specificity. The optimal strategy with which to use these novel biomarkers and highly sensitive troponins has yet to be determined, and interpretation of their results in light of thorough clinical assessment remains essential.

Incremental value of copeptin for rapid rule out of acute myocardial infarction

OBJECTIVES

The purpose of this study was to examine the incremental value of copeptin for rapid rule out of acute myocardial infarction (AMI).

BACKGROUND

The rapid and reliable exclusion of AMI is a major unmet clinical need. Copeptin, the C-terminal part of the vasopressin prohormone, as a marker of acute endogenous stress may be useful in this setting.

METHODS

In 487 consecutive patients presenting to the emergency department with symptoms suggestive of AMI, we measured levels of copeptin at presentation, using a novel sandwich immunoluminometric assay in a blinded fashion. The final diagnosis was adjudicated by 2 independent cardiologists using all available data.

RESULTS

The adjudicated final diagnosis was AMI in 81 patients (17%). Copeptin levels were significantly higher in AMI patients compared with those in patients having other diagnoses (median 20.8 pmol/l vs. 6.0 pmol/l, p < 0.001). The combination of troponin T and copeptin at initial presentation resulted in an area under the receiver-operating characteristic curve of 0.97 (95% confidence interval: 0.95 to 0.98), which was significantly higher than the 0.86 (95% confidence interval: 0.80 to 0.92) for troponin T alone (p < 0.001). A copeptin level <14 pmol/l in combination with a troponin T < or =0.01 microg/l correctly ruled out AMI with a sensitivity of 98.8% and a negative predictive value of 99.7%.

CONCLUSIONS

The additional use of copeptin seems to allow a rapid and reliable rule out of AMI already at presentation and may thereby obviate the need for prolonged monitoring and serial blood sampling in the majority of patients. (Advantageous Predictors of Acute Coronary Syndromes Evaluation [APACE]; NCT00470587).

How many ECG leads do we need?

The number of leads needed in clinical electrocardiography depends on the clinical problem to be solved. The standard 12-lead ECG is so well established that alternative lead systems must prove their advantage through well-conducted clinical studies to achieve clinical acceptance. Certain additional leads seem to add valuable information in specific patient groups. The use of a large number of leads (eg, in body surface potential mapping) may add clinically relevant information, but it is cumbersome and its clinical advantage is yet to be proven. Reduced lead sets emulate the 12-lead ECG reasonably well and are especially advantageous in emergency situations.

Body surface mapping versus the standard 12 lead ECG in the detection of myocardial infarction amongst emergency department patients: a Bayesian approach

OBJECTIVE

To determine if body surface mapping (BSM) is better than the standard 12 lead ECG in the diagnosis of acute myocardial infarction amongst emergency department patients.

SETTING

A University affiliated inner-city emergency department.

PARTICIPANTS

People presenting to an emergency department with symptoms compatible with myocardial ischaemia/infarction.

MAIN OUTCOME MEASURES

Myocardial infarction as defined by either standard 12 lead ECG changes with associated cardiac marker rise, Troponin T >0.1 microg/ml at > 12 h or autopsy/surgical findings of fresh macroscopic infarction.

RESULTS

BSM had an overall sensitivity of 47.1% versus 40% for the 12 lead ECG (P < 0.001). Specificity for the BSM was 85.6% versus 93.7% for the 12 lead ECG (P < 0.001). These findings were consistent for low/moderate and high risk subgroups. Bayesian analysis demonstrates that indiscriminate use of BSM would result in a clinically important overdiagnosis of myocardial infarction amongst emergency department patients.

CONCLUSIONS

BSM has a higher sensitivity, but a lower specificity for the diagnosis of myocardial infarction.