While assessing a patient with chest pain consistent with acute myocardial infarction (AMI) or unstable angina, the emergency physician must first estimate the patient's probability of acute cardiac ischemia (ACI), a term that refers collectively to the spectrum of acute ischemic states. This first estimate of the short-term probability of ACI is inferred from the history, physical examination, and electrocardiogram (ECG). In some settings, an initial CK-MB test is also used.23 Hedges J.R. The role of CK-MD in chest pain decision-making J Accident Emerg Med 1995 ; 12 : 101-106 [cross-ref]
Cliquez ici pour aller à la section Références Patients who meet the physician and hospital's threshold for ACI are further evaluated in the hospital to confirm or exclude this diagnosis, while other life-threatening diagnoses are excluded.64 Zalenski R.J., Roberts R.R. Chest pain The Clinical Practice of Emergency Medicine Philadelphia: JB Lippincott (1996).
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To manage patients safely, the emergency physician must then make a second, different decision regarding the site of further testing and monitoring. The risk of life-threatening events determines the intensity of monitoring needed during diagnostic testing and thus the site of further medical care. Each of the potentially available choices, the coronary care unit (CCU), the intermediate care unit, the emergency department (ED) chest pain observation unit (CPOU), the hospital ward, or the outpatient setting, has its specific level of intensity, cost, and benefit. Appropriate patient selection requires a second, critical estimate: the probability of a short-term life-threatening event. This probability is the key variable for determining the necessary level of care.8 Brush J.E., Brand D.A., Acampora D. , et al. Use of the initial electrocardiogram to predict in-hospital complications of acute myocardial infarction N Engl J Med 1985 ; 312 : 1137-1141 [cross-ref]
Cliquez ici pour aller à la section Références, 18 Goldman L., Cook E.F., Johnson P.A. , et al. Prediction of the need for intensive care in patients who come to emergency departments with acute chest pain N Engl J Med 1996 ; 334 : 1498-1504 [cross-ref]
Cliquez ici pour aller à la section Références This estimate must be used to match the availability of intensive, expensive resources appropriately (e.g., one-to-one nursing care) to the patients most likely to need them. Because admission to the CCU is widely viewed as conferring a 15% survival advantage on patients (with cardiac arrest), making the correct decision about disposition is important.56 Tosteson A.N., Goldman L., Udvarhelyi I.S. , et al. Cost-effectiveness of a coronary care unit versus an intermediate care unit for emergency department patients with chest pain Circulation 1996 ; 94 : 143-150
Cliquez ici pour aller à la section Références Figure 1 depicts the pathway the emergency physician should take in making these decisions.
The CCU should be reserved for patients at higher risk for life-threatening events, the intermediate care unit for patients at lower risk for events but at higher probability for ACI;15 Fineberg H.V., Scadden D., Goldman L. Care of patients with a low probability of acute myocardial infarction: Cost effectiveness of alternatives to coronary-care-unit admission N Engl J Med 1984 ; 310 : 1301-1307 [cross-ref]
Cliquez ici pour aller à la section Références, 17 Gaspoz J.M., Lee T.L., Weinstein M.C., Cook E.F. , et al. Cost-effectiveness of a new short-stay unit to “rule out” acute myocardial infarction in low risk patients J Am Coll Cardiol 1994 ; 24 : 1249-1259 [cross-ref]
Cliquez ici pour aller à la section Références, 65 Zalenski R.J., Rydman R.J., McCarren M. , et al. Feasibility of a rapid diagnostic protocol for an emergency department chest pain unit Ann Emerg Med 1997 ; 29 : 99-108 [cross-ref]
Cliquez ici pour aller à la section Références the ED CPOU for patients at low risk (for events and ACI (but not low enough to be discharged,17 Gaspoz J.M., Lee T.L., Weinstein M.C., Cook E.F. , et al. Cost-effectiveness of a new short-stay unit to “rule out” acute myocardial infarction in low risk patients J Am Coll Cardiol 1994 ; 24 : 1249-1259 [cross-ref]
Cliquez ici pour aller à la section Références, 46 Roberts R.R., Zalenski R.J., Mensah E.K. , et al. Costs of emergency department–based accelerated diagnostic protocol vs hospitalization in patients with chest pain: A randomized controlled trial JAMA 1997 ; 278 : 1670-1676
Cliquez ici pour aller à la section Références, 63 Zalenski R.J., McCarren M., Roberts R. , et al. An evaluation of a chest pain diagnostic protocol to exclude acute cardiac ischemia in the emergency department Arch Intern Med 1997 ; 157 : 1085-1091
Cliquez ici pour aller à la section Références, 65 Zalenski R.J., Rydman R.J., McCarren M. , et al. Feasibility of a rapid diagnostic protocol for an emergency department chest pain unit Ann Emerg Med 1997 ; 29 : 99-108 [cross-ref]
Cliquez ici pour aller à la section Références and a timely community-based evaluation in the outpatient setting, for patients who are at low risk in the short term but at higher risk for cardiac events over the following 1 to 24 months.34 Karlson B.W., Wiklund I., Bengtson A. , et al. Prognosis and symptoms one year after discharge from the emergency department in patients with acute chest pain Chest 1994 ; 105 : 1442-1447 [cross-ref]
Cliquez ici pour aller à la section Références, 58 Villaneuva F.S., Sabia P.J., Afrookteh A. , et al. Value and limitations of current methods of evaluating patients present to the emergency room with cardiac-related symptoms for determining long-term prognosis Am J Cardiol 1992 ; 69 : 746-750
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The wide spectrum of settings for the evaluation of ACI has evolved only over the last 10 years. Intermediate care units and ED-based CPOUs are part of these developments and of the trend to increase the specificity of treatment and to decrease hospital use and the cost of care.17 Gaspoz J.M., Lee T.L., Weinstein M.C., Cook E.F. , et al. Cost-effectiveness of a new short-stay unit to “rule out” acute myocardial infarction in low risk patients J Am Coll Cardiol 1994 ; 24 : 1249-1259 [cross-ref]
Cliquez ici pour aller à la section Références, 46 Roberts R.R., Zalenski R.J., Mensah E.K. , et al. Costs of emergency department–based accelerated diagnostic protocol vs hospitalization in patients with chest pain: A randomized controlled trial JAMA 1997 ; 278 : 1670-1676
Cliquez ici pour aller à la section Références, 63 Zalenski R.J., McCarren M., Roberts R. , et al. An evaluation of a chest pain diagnostic protocol to exclude acute cardiac ischemia in the emergency department Arch Intern Med 1997 ; 157 : 1085-1091
Cliquez ici pour aller à la section Références, 65 Zalenski R.J., Rydman R.J., McCarren M. , et al. Feasibility of a rapid diagnostic protocol for an emergency department chest pain unit Ann Emerg Med 1997 ; 29 : 99-108 [cross-ref]
Cliquez ici pour aller à la section Références Utilization rates from the Multicenter Chest Pain Study (MCPS) show an astounding reversal of CCU and telemetry use.18 Goldman L., Cook E.F., Johnson P.A. , et al. Prediction of the need for intensive care in patients who come to emergency departments with acute chest pain N Engl J Med 1996 ; 334 : 1498-1504 [cross-ref]
Cliquez ici pour aller à la section Références From 1984 to 1986, in a large sample of patients studied with acute chest pain (derivation set), 18% were admitted to intermediate care and 78% to the CCU. In the period from 1990 to 1994, in another set of patients studied (validation set), 84% were admitted to intermediate care and 16% to the CCU.18 Goldman L., Cook E.F., Johnson P.A. , et al. Prediction of the need for intensive care in patients who come to emergency departments with acute chest pain N Engl J Med 1996 ; 334 : 1498-1504 [cross-ref]
Cliquez ici pour aller à la section Références During these same two comparison periods, the “rule in” AMI rate for the CCU increased from 31% to 50% and for intermediate care from 4% to 31% (p<0.001).18 Goldman L., Cook E.F., Johnson P.A. , et al. Prediction of the need for intensive care in patients who come to emergency departments with acute chest pain N Engl J Med 1996 ; 334 : 1498-1504 [cross-ref]
Cliquez ici pour aller à la section Références The shift away from using intensive settings for monitoring patients is in further evidence in the recommendations made 1994 by the prestigious National Institutes of Health and endorsed by the American College of Emergency Physicians: that low-risk patients with symptoms of unstable angina should be evaluated in the outpatient setting.6 Braunwald E., Mark D.B., Jones R.H. , et al. Unstable Angina: Diagnosis and Management: Clinical Practice Guideline Number 10, AHCPR Publication No. 94-0602 Rockville, MD: Agency for Health Care Policy and Research and the National Heart, Lung, and Blood Institute, Public Health Service, U.S. Department of Health and Human Services (March 1994).
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To manage patients safely in this new paradigm, the emergency physician must understand that the risk of complications determines the intensity of monitoring needed during diagnostic testing.6 Braunwald E., Mark D.B., Jones R.H. , et al. Unstable Angina: Diagnosis and Management: Clinical Practice Guideline Number 10, AHCPR Publication No. 94-0602 Rockville, MD: Agency for Health Care Policy and Research and the National Heart, Lung, and Blood Institute, Public Health Service, U.S. Department of Health and Human Services (March 1994).
Cliquez ici pour aller à la section Références, 18 Goldman L., Cook E.F., Johnson P.A. , et al. Prediction of the need for intensive care in patients who come to emergency departments with acute chest pain N Engl J Med 1996 ; 334 : 1498-1504 [cross-ref]
Cliquez ici pour aller à la section Références Appropriately matching a patient's risk to the intensity of service is the solution that reconciles the conflicting priorities with every practicing emergency physician is familiar: minimizing the inappropriate discharge of patients with ACI while maximizing the cost-effectiveness of hospital-based care. Missed AMI is the leading cause of settlement costs because of malpractice in the ED setting48 Rusnak R.A., Stair T.O., Hansen K. , et al. Litigation against the emergency physician: Common features in cases of missed myocardial infarction Ann Emerg Med 1989 ; 18 : 1029-1034 [cross-ref]
Cliquez ici pour aller à la section Références; in addition, the high estimated mortality rate (25%) of the 2% to 4% of patients inappropriately discharged with AMI is cause for concern.37 Lee T.H., Rouan G.W., Weisberg M.C. , et al. Clinical characteristics and natural history of patients with acute myocardial infarction sent home from the emergency room Am J Cardiol 1987 ; 60 : 219-224 [cross-ref]
Cliquez ici pour aller à la section Références, 42 McCarthy B.D., Beshansky J.R., D'Agostino R.B. , et al. Missed diagnoses of acute myocardial infarction in the emergency department: Results from a multicenter study Ann Emerg Med 1993 ; 22 : 579-582 [cross-ref]
Cliquez ici pour aller à la section Références Perhaps because of this concern there has been an excess of monitoring of chest pain patients in the CCU who are found to be nonischemic and who received no measurable benefit. This has driven the numerous attempts to achieve more cost-effective risk stratification.6 Braunwald E., Mark D.B., Jones R.H. , et al. Unstable Angina: Diagnosis and Management: Clinical Practice Guideline Number 10, AHCPR Publication No. 94-0602 Rockville, MD: Agency for Health Care Policy and Research and the National Heart, Lung, and Blood Institute, Public Health Service, U.S. Department of Health and Human Services (March 1994).
Cliquez ici pour aller à la section Références, 17 Gaspoz J.M., Lee T.L., Weinstein M.C., Cook E.F. , et al. Cost-effectiveness of a new short-stay unit to “rule out” acute myocardial infarction in low risk patients J Am Coll Cardiol 1994 ; 24 : 1249-1259 [cross-ref]
Cliquez ici pour aller à la section Références, 36 Lee T.H., Juarez G., Cook F. , et al. Ruling out acute myocardial infarction: A prospective multicenter validation of a 12-hour strategy for patients at low risk N Engl J Med 1991 ; 324 : 1239-1246 [cross-ref]
Cliquez ici pour aller à la section Références, 46 Roberts R.R., Zalenski R.J., Mensah E.K. , et al. Costs of emergency department–based accelerated diagnostic protocol vs hospitalization in patients with chest pain: A randomized controlled trial JAMA 1997 ; 278 : 1670-1676
Cliquez ici pour aller à la section Références, 63 Zalenski R.J., McCarren M., Roberts R. , et al. An evaluation of a chest pain diagnostic protocol to exclude acute cardiac ischemia in the emergency department Arch Intern Med 1997 ; 157 : 1085-1091
Cliquez ici pour aller à la section Références Achieving cost-effectiveness and high sensitivity for ACI, in fact, can occur only by using less expensive settings for the workup of ACI, such as the ED-based CPOU.17 Gaspoz J.M., Lee T.L., Weinstein M.C., Cook E.F. , et al. Cost-effectiveness of a new short-stay unit to “rule out” acute myocardial infarction in low risk patients J Am Coll Cardiol 1994 ; 24 : 1249-1259 [cross-ref]
Cliquez ici pour aller à la section Références, 50 Schroeder J.S., Lamb I.H., Hu M. Do patients in whom myocardial infarction has been ruled out have a better prognosis after hospitalization than those surviving infarction? N Engl J Med 1980 ; 303 : 1-5 [cross-ref]
Cliquez ici pour aller à la section Références This allows a reduction in the cost of care that partly or wholly offsets the cost of achieving the priority of carefully examining and testing patients who are at low risk of ACI.65 Zalenski R.J., Rydman R.J., McCarren M. , et al. Feasibility of a rapid diagnostic protocol for an emergency department chest pain unit Ann Emerg Med 1997 ; 29 : 99-108 [cross-ref]
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The focus of this article is the prediction of life-threatening events with ED measurements. These events include malignant arrythmias (e.g., ventricular fibrillation, tachycardia, and high-grade atrioventricular [AV] block), pump failure (e.g., cardiogenic shock and congestive heart failure), cardiac arrest, and death. The ED measures include the history, physical examination, ECG, and their combinations. The authors also examine the prognostic value of newer cardiac markers and imaging tests. In a final section, we extend the risk stratification to patients who are at longer-term risk of cardiac death from 1 month to 2 years postdischarge. Such patients are commonly discharged from the ICU.
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