Serum markers in the emergency department diagnosis of acute myocardial infarction

No currently used cardiac-specific serum marker meets all the criteria for an "ideal" marker of AMI. No test is both highly sensitive and highly specific for acute infarction within 6 hours following the onset of chest pain, the timeframe of interest to most emergency physicians in making diagnostic and therapeutic decisions. Patients presenting to the ED with chest pain or other symptoms suggestive of acute cardiac ischemia therefore cannot make a diagnosis of AMI excluded on the basis of a single cardiac marker value obtained within a few hours after symptom onset. The total CK level is far too insensitive and nonspecific a test to be used to diagnose AMI. It retains its value, however, as a screening test, and serum of patients with abnormal total CK values should undergo a CK-MBmass assay. Elevation in CK-MB is a vital component of ultimate diagnosis of AMI, but levels of this marker are normal in one fourth to one half of patients with AMI at the time of ED presentation. The test is highly specific, however, and an abnormal value (particularly when it exceeds 5% of the total CK value) at any time in a patient with chest pain is highly suggestive of an AMI. There have been several improvements of CK-MB assay timing and subform quantification that appear highly useful for emergency physicians. Rapid serial CK-MB assessment greatly increases the diagnostic value of the assay in a timeframe suitable for ED purposes but unfortunately still misses about 10% of patients ultimately diagnosed with acute MI. Assays of CK-MB subforms have very high sensitivity, and, although unreliable within 4 hours of symptom onset, have excellent diagnostic value at 6 or more hours after chest pain begins. Automated test assays recently have become available and could prove applicable to ED settings. The cardiac troponins are highly useful as markers of acute coronary syndromes, rather than specifically of AMI, and abnormal values at any time following chest pain onset are highly predictive of an adverse cardiac event. The ED applicability of the troponins is severely limited, however, because values remain normal in most patients with acute cardiac events as long as 6 hours following symptom onset. Myoglobin appeared promising as a marker of early cardiac ischemia but appears to be only marginally more sensitive than CK-MB assays early after symptom onset and less sensitive than CK-MB at 8 hours or more after chest pain starts. Rapid serial myoglobin assessment, however, appears highly useful as an early marker of AMI. The marker has a very narrow diagnostic window. The clinician is left with several tests that are highly effective in correctly identifying patients with AMI (or at high risk for AMI), but none that can dependably exclude patients with acute coronary syndromes soon after chest pain onset. A prudent strategy when assessing ED patients with chest pain and nondiagnostic ECGs is to order CK-MB and troponin values on presentation in the hope of making an early diagnosis of AMI or unstable coronary syndrome. Although it is recognized that normal values obtained within 6 hours of symptom onset do not exclude an acute coronary syndrome, patients at low clinical risk and having normal cardiac marker tests could be provisionally admitted to low-acuity hospital settings or ED observation. After 6 to 8 hours of symptom duration has elapsed, the cardiac-specific markers are highly effective in diagnosing AMI, and such values obtained can be used more appropriately to make final disposition decisions. At no time should results of serum marker tests outweigh ECG findings or clinical assessment of the patient's risk and stability.     

The Etiology and Prognostic Significance of Cardiac Troponin I Elevation in Unselected Emergency Department Patients

Background: Cardiac troponin elevations are associated not only with acute coronary syndromes (ACS) but also with multiple other cardiac and non-cardiac conditions. Study Objectives: To investigate the etiology and clinical significance of cardiac troponin I elevations in an unselected Emergency Department (ED) patient cohort. Methods: The study population consisted of 991 consecutive troponin-positive patients admitted to the ED of a university hospital with ACS as the presumptive diagnosis. Cardiac troponin I was measured on admission and a follow-up sample was obtained at 6–12 h. Clinical diagnosis was ascertained retrospectively using all the available information including electrocardiogram, clinical data, laboratory tests, and available coronary angiograms. Results: At admission, 805 (81.2%) patients were already troponin positive; of these, the troponin elevation was related to myocardial infarction (MI) in 654 (81.2%) patients. Finally, 83.0% of the troponin elevations were due to MI, 7.9% were related to other cardiac causes, and 9.1% to non-cardiac diseases. The leading non-cardiac causes were pulmonary embolism, renal failure, pneumonia, and sepsis. Non-cardiac patients with elevated troponin I at admission showed significantly higher in-hospital mortality (26.7% vs. 13.4%, p = 0.002) compared to cardiac patients. Conclusion: Elevated troponin levels for reasons other than MI are common in the ED and are a marker of poor in-hospital prognosis.     

Minor elevations in troponin T values enhance risk assessment in emergency department patients with suspected myocardial ischemia: analysis of novel troponin T cut-off values

BACKGROUND: A consensus document developed by a joint committee of the European Society of Cardiology and the American College of Cardiology redefines myocardial infarction (MI) using an increase of troponin I or T as compared to a reference control population (i.e., troponin T (TnT) of 0.01 microg/l). A clinical problem arises when an arbitrary cut-off point is selected for determination of MI (i.e., TnT> or =0.1 microg/l), as minor elevations of troponin are associated with increased cardiovascular risk in selected patients with acute coronary syndromes. METHODS: We prospectively studied 420 unselected patients being evaluated for suspected myocardial ischemia in the emergency department (ED). We compared a 99th percentile MI cut-off limit for TnT, determined by constructing a standard receiver operator curve from our ED population in whom an acute coronary syndrome was excluded, to a standard MI cut-off limit of 0.1 microg/l in assessing cardiovascular risk. We also assessed the prognostic value of detectable TnT concentrations below this 99th percentile MI cut-off, but above the upper reference limit of healthy controls. RESULTS: The diagnosis of acute coronary syndromes (ACS) was more frequent in groups with higher TnT concentrations: 16.8% with a normal TnT (<0.03 microg/l), 29.5% with detectable TnT below the 99th percentile MI limit (0.03-0.066 microg/l), 64.3% with detectable TnT between the 99th percentile and standard MI cut-offs (0.067-0.099 microg/l), and 85.4% with TnT> or =0.1 microg/l (p<0.001 for the trend). Thirty-day cardiovascular event rates increased for any detectable concentration of troponin: 1.3% with normal TnT, 4.8% with detectable TnT below the 99th percentile MI limit, 15.4% with TnT between the 99th percentile and standard MI cut-off limits, and 12.5% with TnT> or =0.1 microg/l (p<0.01 for the trend). CONCLUSION: Using an MI cut-off concentration for TnT from a "non-ACS reference" improves risk stratification, but fails to detect a positive TnT in 11.7% of subjects with an acute coronary syndrome.     

It is safe to manage selected patients with acute coronary syndromes in unmonitored beds

This prospective, observational study evaluated the safety of the Western Hospital admission protocol for patients with suspected acute coronary syndromes. The study included all patients admitted from the Emergency Department with an admission diagnosis of unstable angina, post infarct angina, atypical chest pain, or chest pain for evaluation. Data collected included demographic data, admission diagnosis, location of admission (bed with or without cardiac monitoring), past medical history and presenting chest pain history to determine Agency for Health Care Policy (AHCPR) and Western Hospital (WH) protocol classifications, cardiac enzyme assays, electrocardiogram analysis, adverse outcomes [death, myocardial infarction (MI), dysrhythmia, acute pulmonary edema, recurrent pain], diagnosis at hospital discharge, and length of stay-(LOS). There were 508 patients with a mean age of 63.7 years enrolled in the study. Three hundred nineteen (62.8%) were admitted to beds without any cardiac monitoring. There was one unexpected death in the unmonitored group, an 85 year-old patient who suffered a presumed dysrhythmia and whom the treating physician had decided was not for resuscitation. Twelve patients suffered nonfatal MI, and none suffered pulmonary edema. All MI patients made an uneventful recovery, and none required thrombolysis. If all patients had been admitted to an area of care based on AHCPR guidelines, an additional 310 admissions to monitored beds would have been required. The results of this study suggest that selected patients with suspected acute coronary syndromes can be safely managed in beds without continuous cardiac monitoring.     

Newer antithrombotic strategies in the initial management of non-ST-segment elevation acute coronary syndromes

OBJECTIVE: To review the place in therapy of currently available antithrombotic agents in the non-ST-segment elevation acute coronary syndromes, that is, unstable angina and non-Q-wave myocardial infarction (MI). Recommendations are made based on currently available data. DATA SOURCE: English-language clinical studies, position statements, and review articles pertaining to the management of unstable angina and non-Q-wave MI with currently available products. STUDY SELECTION: Selection of prospective clinical studies was limited to those focusing on the management of the non-ST-segment elevation acute coronary syndromes, unstable angina, and non-Q-wave MI. DATA SYNTHESIS: It has yet to be determined which combination of agents (dalteparin, enoxaparin, lepirudin, clopidogrel, ticlopidine, abciximab, eptifibatide, tirofiban) and procedural strategies most significantly reduces mortality and serious events in these patients. The relevant pathophysiology, diagnostic criteria, and risk-stratifying procedures are reviewed in context with information from clinical studies regarding currently available agents for the management of non-ST-segment elevation acute coronary syndromes. CONCLUSIONS: A large number of new therapeutic classes and agents are available for the treatment of unstable angina and non-Q-wave MI. Although the diagnoses of unstable angina or non-Q-wave MI identify risk, treatment decisions are often based on the presence or absence of ST-segment elevations. Limited prospective evidence delineates the proper utilization of resources to best manage these patients. Efforts should be aimed at identifying particular patients who will best benefit from recently available therapies.     

Introduction of an accelerated diagnostic protocol in the assessment of emergency department patients with possible acute coronary syndrome: The Nambour Short Low‐Intermediate Chest pain project

Emergency physicians can feel pressured by opposing forces of clinical reality and the need to publish successful key performance indicators in an environment of increasing demands and cost containment. This is particularly relevant to management of patients with undifferentiated chest pain and possible acute coronary syndrome. Unreliability of clinical assessment and high risk of adverse outcomes for all concerned exist, yet national guidelines are at odds with efforts to reduce ED crowding and access block. We report findings from the Nambour Short Low‐Intermediate Chest pain risk trial, which safely introduced an accelerated diagnostic protocol with reduced ED length of stay and high patient acceptability. Over a 7‐month period, there were no major adverse cardiac events by 30 days in 19% of undifferentiated chest pain presentations with possible acute coronary syndrome discharged after normal sensitive cardiac troponin taken 2 h after presentation and scheduled to return for outpatient exercise stress test.     

Medicolegal aspects of acute myocardial infarction

Emergency physicians face significant liability in the diagnosis and management of patients with acute coronary syndromes. Newer diagnostic and therapeutic modalities continue to add to the tools that assist in sorting through the complexities of this group of patients. Nonetheless, the legal pitfalls continue unabated. Prudent patient care dictates vigilance in recognizing the atypical presentations, streamlining policies and procedures in the ED that impact on the management of these patients, and remembering that managed care policies affect payment, and not patient care.     

Normal CK, elevated MB predicts complications in acute coronary syndromes

The implications of an elevated Creatine kinase (CK)-MB isoenzyme (MB) in suspected acute coronary syndromes, with a normal total CK, is not well established. Despite many guidelines on managing patients with acute coronary ischemia, none indicates strategies for patients with elevated MB and with a normal CK. The outcome consequence of this result is not firmly established. Our objective was to prospectively evaluate outcomes in patients with suspected acute coronary syndromes, normal initial total CK, and increased MB. All Emergency Department patients with suspected acute coronary syndromes and creatinine <2.0 mg/dL were eligible for study entry. Serial CK and MB fractions were measured on arrival in the Emergency Department, then 8 and 16 h postpresentation. A composite outcome of death, Q-wave myocardial infarction, or revascularization was defined at the index visit and 6 months later. Outcomes were determined by blinded record review and by telephone contact. In the 698 patients entered, the acute composite outcome rate was 25% (175) and 6.3% (44) at 6 months. Acute and 6 month adverse outcome rates were statistically the same for all patients with an elevated MB fraction, regardless of the total CK level. An elevated MB conferred a higher event rate than did a normal MB. We conclude that the adverse event rate for patients with suspected acute coronary syndromes and an elevated MB is the same whether or not the total CK is elevated. These patients should be considered as having had an acute coronary syndrome.     

Outcome of low-risk patients discharged home after a normal cardiac troponin I

Patients with symptoms suggestive of, but at low risk for, acute coronary syndrome (ACS), who have a negative electrocardiogram (EKG) and a single normal troponin I at 6–9 h after symptom onset are frequently discharged from our Emergency Department (ED). We sought to determine their rate of adverse cardiac events at 30 days (ACE-30), defined as cardiac death or myocardial infarction (MI), by chart review, telephone interview, or county death records. Of 663 patients, data were available for 588 (89%). Mean age was 48 years; 59% were male. There were 390 patients (66%) who complained of chest pain. Previous coronary artery disease (CAD) was reported in 145 patients (25%). Two patients (0.34%) had ACE-30, both with non-ST elevation MI. There were no cases of cardiac death. None of the patients died in Hennepin County within 30 days. At our institution, low-risk patients with symptoms suggestive of ACS who are discharged home after a normal cTnI drawn 6–9 h after symptom onset have a very low incidence of cardiac events at 30 days.     

The use of adjunctive anticoagulants in patients with acute coronary syndrome transitioning to percutaneous coronary intervention

Patients presenting to the Emergency Department (ED) need to be quickly diagnosed, risk-stratified, and treated accordingly. Anticoagulants used in the ED should be easy to use and suitable for all patients with acute coronary syndromes, regardless of treatment strategy. In patients with ST-segment myocardial infarction, current guidelines recommend unfractionated heparin regardless of reperfusion strategy or low-molecular-weight heparin (LMWH) as an alternative in patients undergoing percutaneous coronary intervention (PCI). The LMWH enoxaparin is approved for ST-segment elevation myocardial infarction patients managed medically or undergoing PCI. The recently updated American College of Cardiology/American Heart Association guidelines for patients with unstable angina or non-ST-segment elevation myocardial infarction recommend unfractionated heparin or the LMWH enoxaparin (class IA recommendation), or the factor Xa inhibitor fondaparinux or the direct thrombin inhibitor bivalirudin (class IB recommendation) for patients managed invasively. This review discusses each of these anticoagulant options in the context of patients transitioning to PCI.     

Provision of clinically based information improves patients' perceived length of stay and satisfaction with EP

We conducted a focused, prospective, randomized study to evaluate whether periodic personal provision of clinically based information to patients during an Emergency Department (ED) visit improves patients' perceptions of physician's excellence and efficiency of patient care. Six hundred nineteen consecutive adult patients or proxy informants, who were evaluated in the ED and subsequently discharged, were randomized into the standard of care (n = 307) and intervention group (n = 312). Under supervision by ED attending physicians, a single research assistant periodically provided patients with process and medical information at 15-minute intervals, starting at arrival and continuing through until discharged from the ED. At discharge, patients were handed a previously validated questionnaire to fill out and drop off at the ED exit. Outcome measures included actual and patients' estimate of the wait time (WT) and length of stay (LOS), ratings of registration personnel, and ratings of bedside and technical skills of nurses and Emergency Physicians (EPs), by using a 5-point Likert scale (5 = excellent, 4 = very good, 3 = good, 2 = fair, 1 = poor). There were no statistically significant differences in age, sex, insurance data, intensity of service, actual WT, actual LOS, and patients' perceived WT to see a physician between the 2 groups. The perceived LOS was, however, significantly shorter (92.6 vs. 105.5 min, P =.027) and the proportion of patients who rated the Emergency Staff Physician as "excellent" or "very good" was significantly higher in the intervention group (Bedside: 87.1% vs. 80.5%, P =.033; Technical skill: 86.8% vs. 80.1%, P =.032). Patients' perception of nursing skills were, however, statistically similar in the 2 groups (Bedside: 83.1% vs. 83.0%, P =.942; Technical skill: 84.5% vs. 82.7%, P =.613). Given the sample size and observed proportions, the chi(2) analysis of perception of nursing skill had a power of 4.8% (registered nurse [RN] bedside) and 7.5% (RN technical skill). Periodic personal interaction and provision of clinically based information in the ED is thought to improve patients' perceived LOS, efficiency, and clinical skills of EP after an ED visit.     

Whole blood choline and plasma choline in acute coronary syndromes: prognostic and pathophysiological implications

BACKGROUND: Whole blood choline (WBCHO) and plasma choline (PLCHO) concentrations increase rapidly after stimulation of phospholipase D in acute coronary syndromes (ACS). Early risk-stratification was analyzed in 217 patients with suspected ACS and a negative admission troponin T (<0.03 microg/L). METHODS: WBCHO and PLCHO were measured using high-performance-liquid-chromatography mass spectrometry. Major cardiac events (MACE) were defined as cardiac death/arrest, coronary intervention or myocardial infarction (MI). RESULTS: WBCHO (> or = 28.2 micromol/L) was predictive for MACE (hazard ratio [HR] 2.7; p<0.001), cardiac death/arrest (HR 4.2; p=0.015), heart failure (HR 2.8; p=0.003), coronary intervention (HR 2.1; p=0.01) and MI (HR 8.4; p=0.002) after 30 days. PLCHO (> or = 25.0 micromol/L) was predictive for MACE (HR 2.6; p=0.005), cardiac death/arrest (HR 15.7; p<0.001), heart failure (HR 6.0; p<0.001) but not for coronary intervention and MI. WBCHO and PLCHO were predictive for MACE in multivariate analysis (Odds ratio [OR] 2.7, p=0.009 and OR 3.3, p=0.03) independently of age, gender, prior MI, coronary risk factors and ECG. CONCLUSIONS: WBCHO and PLCHO are significant and independent predictors of major cardiac events in admission troponin T negative acute coronary syndromes. Both are predictive for events related to tissue ischemia and WBCHO is capable of detecting risks associated with coronary plaque instability.     

Clinical efficacy of three assays for cardiac troponin I for risk stratification in acute coronary syndromes: a Thrombolysis In Myocardial Infarction (TIMI) 11B Substudy

BACKGROUND: Significant analytic variability exists between the multiple assays for cardiac troponin I (cTnI) approved for clinical use. Until adequate cTnI standardization is possible, an evidence-based approach evaluating each assay at specific thresholds appears warranted. METHODS: We examined the efficacy of three cTnI assays for predicting death, myocardial infarction (MI), or the composite of death, MI, or urgent revascularization at 43 days among patients with non-ST-elevation acute coronary syndromes enrolled in the Thrombolysis In Myocardial Infarction (TIMI) 11B study. RESULTS: Six hundred eighty-one patients with serum samples obtained at baseline and/or 12-24 h had cTnI determined using all three assays. Baseline cTnI was > or = 0.1 microg/L for 368, 395, and 418 patients with the Bayer Immuno 1(TM), ACS:180, and Dimension RxL assays, respectively. Correlation coefficients for the RxL with the ACS:180 and Bayer Immuno 1 results were 0.89 (P = 0.0001) and 0.87 (P = 0.0001), with a coefficient of 0.92 (P = 0.0001) for the ACS:180 and Bayer Immuno 1 assays. Patients with cTnI > or = 0.1 microg/L were at increased risk fo death or MI by 43 days (relative risk, 2.2-3.0; P <0.0006), regardless of the assay used. This prognostic capacity persisted among those with creatine kinase MB isoenzyme concentrations within the reference interval. Moreover, cTnI was the strongest multivariate predictor of death, MI, or urgent revascularization with adjusted odds ratios of 2.1-2.9 (P <0. 0006). CONCLUSION: This study demonstrates the prognostic efficacy of three independently developed cTnI assays at a threshold of 0.1 microg/L for the prediction of adverse clinical outcomes among patients with non-ST-elevation acute coronary syndromes.     

Transient pathological Q waves in suspected acute myocardial infarction: 'electrical stunning'

In acute coronary syndromes the development of pathological Q waves is usually taken as evidence of established myocardial infarction (MI). We describe two patients with suspected acute MI who developed transient pathological Q waves. Cardiac enzymes were normal and cardiac catheterisation showed severe proximal coronary disease. Recognition of 'non-infarction' Q waves is important and may influence management of these patients.     

Inflammation, the acute phase response and atherosclerosis.

There is increasing evidence that atherosclerosis is a chronic inflammatory disorder resulting from a combination of processes, and that acute exacerbations of this inflammation are associated with the acute coronary syndromes such as myocardial infarction and unstable angina. Measurement of the serum level of acute phase proteins, such as C-reactive protein and serum amyloid A protein, has been used to predict the risk of acute events in patients with atherosclerosis. Prospective studies have shown that higher serum acute phase protein levels, often within the reference range, are associated with increased risk of myocardial infarction (MI), stroke or peripheral vascular disease and predict risk of infarction and death among high-risk patients. These observations have important implications for the assessment of patients and for treatment.     

Coronary angiographic findings in patients with cocaine-associated chest pain

Patients who present to the Emergency Department (ED) with chest pain associated with cocaine use are a common problem. The incidence and predictors of underlying significant coronary disease in patients with and without myocardial infarction (MI) has not been well described. Patients who underwent coronary angiography within 5 weeks of an ED evaluation for cocaine-associated chest pain were studied. Significant disease was defined as > or = 50% stenosis of a coronary artery or major branches or bypass graft. A total of 90 patients underwent coronary angiography. Significant disease was present in 45 (50%), with 1-vessel disease in 32%, 2-vessel disease in 10%, 3-vessel disease in 6%, with significant graft stenosis in 3%. Significant disease was present in 77% of patients with MI or troponin I elevations, compared to only 35% of patients without myonecrosis. Predictors of significant coronary disease included MI or troponin I elevations, prior MI, known coronary disease (prior MI or revascularization), and elevated cholesterol. Only 7 of the 39 patients (18%) without myonecrosis or a history of coronary disease had significant disease on angiography. In conclusion, significant disease is found in the majority of patients with cocaine-associated MI or troponin elevations. In contrast, only a minority of those without myonecrosis have significant coronary disease.     

Adverse outcomes following emergency department discharge of patients with possible acute coronary syndrome

Objective: To determine the proportion of adverse events in patients discharged after ED assessment for possible acute coronary syndrome. Methods: Prospective observational cohort study enrolling consecutive patients presenting with symptoms suggestive of coronary syndrome. Main outcome was the proportion of adverse coronary events (defined a priori) within 30 days. Results: Of 2627 patients, 1819 (69%) were discharged without a diagnosis of coronary syndrome and 808 (31%) were admitted for further investigation and treatment. Of these, 385 (14.7%) were given a final diagnosis of acute coronary syndrome. On 30 day follow up, 18 of the discharged patients were diagnosed with acute coronary syndrome (0.7%; 95% confidence intervals [CI] 0.4–1.1%), 10 with unstable angina (0.4%; 95% CI 0.2–0.7%) and 8 with non‐ST elevation myocardial infarction (0.3%; 95% CI 0.2–0.6%). There were no cases of ST elevation infarction or death. The sensitivity for diagnosis of acute coronary syndromes was 95.5% (95% CI 92.9–97.3%). Average length of stay was 7 h for discharged patients. Forty‐six per cent of patients with diabetes and 47% with a past history of coronary disease were discharged. Subsequent outpatient stress testing was performed in 13.6%. Conclusions: In a large Australian ED, less than 1% of patients presenting with symptoms suggestive of coronary syndrome were discharged and subsequently had a 30 day adverse event. Reducing this proportion by admitting patients with traditional risk factors would markedly increase hospital workload. Opportunities exist to improve both the safety and efficiency of chest pain assessment in the ED.     

Development of an optimized multimarker strategy for early risk assessment of patients with acute coronary syndromes

BACKGROUND: A multitude of biomarkers have been suggested for early risk-assessment in patients admitted to the emergency department with suspected acute coronary syndromes. We used logistic regression synergistically with classification and regression tree (CART) analysis to define a multimarker strategy and the cut-off values and sequencing needed to optimize risk stratification in a low to moderate risk population of the emergency department. METHODS: 432 unselected patients (59.7+/-14.5 y, 60.4% male) admitted to the emergency department (ED) with acute coronary syndromes (ACS) were enrolled. Cardiac troponin I (cTnI), N-terminal pro-B-Type natriuretic peptide (NT-proBNP), high sensitivity C-reactive protein (hsCRP), placental growth factor (PlGF), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and D-dimers were measured by immunoassay and whole blood choline (WBCHO) and plasma choline (PLCHO) were measured using LC/MS from baseline samples. Logistic regression and CART analysis were used to define the importance of the various biomarkers tested and to define their hierarchy with respect to the prediction of major adverse cardiac events (MACE; cardiac death, non-fatal MI, unstable angina, CHF requiring admission, urgent PCI and CABG) over the 42-day follow-up period. RESULTS: A combination of NT-proBNP, WBCHO and Lp-PLA2 with cutoffs identified by CART-analysis was optimal for risk-stratification and superior to all other possible combinations of markers. Increased concentrations of both NT-proBNP (>1400 ng/l) and WBCHO (>21 mumol/l) identified patients with very high risk (RR=2.4, 39% primary endpoint) while low concentrations of NT-proBNP (17 mumol/l additionally identified a subgroup with intermediate risk (RR=3.0, 13.5% primary endpoint) in patients with NT-proBNP concentrations 相似文献   

Diagnosis of acute cardiac ischemia

A better understanding of coronary syndromes allow physicians to appreciate UAP and AMI as part of a continuum of ACI. ACI is a life-threatening condition whose identification can have major economic and therapeutic importance as far as threatening dysrhythmias and preventing or limiting myocardial infarction size. The identification of ACI continues to challenge the skill of even experienced clinicians, yet physicians continue (appropriately) to admit the overwhelming majority of patients with ACI; in the process, they admit many patients without acute ischemia [2], overestimating the likelihood of ischemia in low-risk patients because of magnified concern for this diagnosis for prognostic and therapeutic reasons. Studies of admitting practices from a decade ago have yielded useful clinical information but have shown that neither clinical symptoms nor the ECG could reliably distinguish most patients with ACI from those with other conditions. Most studies have evaluated the accuracy of various technologies for diagnosing ACI, yet only a few have evaluated the clinical impact of routine use. The prehospital 12-lead ECG has moderate sensitivity and specificity for the diagnosis of ACI. It has demonstrated a reduction of the mean time to thrombolysis by 33 minutes and short-term overall mortality in randomized trials. In the general ED setting, only the ACI-TIPI has demonstrated, in a large-scale multicenter clinical trial, a reduction in unnecessary hospitalizations without decreasing the rate of appropriate admission for patients with ACI. The Goldman chest pain protocol has good sensitivity for AMI but was not shown to result in any differences in hospitalization rate, length of stay, or estimated costs in the single clinical impact study performed. The protocol's applicability to patients with UAP has not been evaluated. Single measurement of biomarkers at presentation to the ED has poor sensitivity for AMI, although most biomarkers have high specificity. Serial measurements can greatly increase the sensitivity for AMI while maintaining their excellent specificity. Biomarkers cannot identify most patients with UAP. Finally, diagnostic technologies to evaluate ACI in selected populations, such as echocardiography, sestamibi perfusion imaging, and stress ECG, may have very good to excellent sensitivity; however, they have not been sufficiently studied.     

The utility of the presence or absence of chest pain in patients with suspected acute myocardial infarction

In 422 patients admitted from the emergency department (ED) for suspected acute myocardial infarction, the hypothesis that chest pain that persists on arrival in the ED or recurs during the initial ED evaluation is a useful predictor of acute myocardial infarction (AMI) and complications of coronary ischemia was tested. Compared with patients whose chest pain spontaneously ceased before arrival in the ED, patients whose chest pain persisted or recurred during the initial ED evaluation had a 2.3 times greater risk of interventions (P less than .001), a 1.7 times greater risk of complications (P = .045), a 3.8 times greater risk of life-threatening complications (P = .04), and a 2.4 times greater risk of AMI (P = .005). A third group of patients with suspected AMI never experienced chest pain. This group of patients who never experienced chest pain had a three times higher risk of death (P = .02) compared with patients whose chest pain persisted or recurred in the ED, and a 2.1 times greater risk of intervention (P = .01), a 5.2 times greater risk of life-threatening complication (P = .015), and a 7.9 times greater risk of death (P = .025) compared with patients whose chest pain resolved before arrival in the ED. It was concluded that patients with chest pain that resolves spontaneously before arrival to the ED have a better in-hospital prognosis than any other group.