Comparison of the natural history of new onset and exacerbated chronic ischemic heart disease. The Chest Pain Study Group

A 0/1-Hour Algorithm Using High-Sensitivity Cardiac Troponin

The European Society of Cardiology (ESC) guidelines recommend the use of high-sensitivity cardiac troponin (hs-cTn) 0-hour/1-hour algorithms in patients presenting with suspected non ST elevation myocardial infarction (NSTEMI) as Class I, Level B. This algorithm stratified patients into three group including, rule-out, observe, and rule-in. The introduction of a time axis consisting of a relatively short time, 0-hour/1-hour, is worth mentioning in this algorithm. The specificity and negative predictive value to rule-out of myocardial infarction (MI) was more than 95%, respectively. In prospective Asian study consist of around 400 patients with suspected NSTEMI, "elective" catheter intervention was performed on 13 patients in both rule-out and observe group. None of them had MI, or needed an urgent coronary angiography (CAG) within 30 days. Although there was two patients on whom CAG and percutaneous coronary intervention (PCI) were performed less than 7 hours after presenting to the emergency department (ED), they were classified as moderate risk according to the Framingham Risk Score. The diagnostic performance for patients with suspected NSTEMI to combine the novel risk score with the algorithm would be much improved. The development of excellent assays was also key to establish the algorithm. The hs-cTn assay has limits of detection (LoD) approximately 10-fold lower than those of conventional assays, and their 99th percentiles are analytically very precise. After the emergence of the hs-cTn assays, rises in the cases of NSTEMI were accompanied by a reciprocal reduction in the percentage of patients diagnosed with unstable angina (UA). This excellent algorithm has a possibility to reduce ED crowding and unnecessary CAG.

Identification of chest pain patients appropriate for an emergency department observation unit

There are no perfect tests or algorithms to exclude ACI. Because acute coronary occlusion often occurs in patients with low-grade coronary stenosis, the diagnostic goal of a chest pain diagnostic protocol is not to identify patients with CAD, but rather to identify patients who may be safely discharged home without the development of complications such as MI, unstable angina, death, shock, or CHF over the next 1 to 6 months. There is an advantage to evaluating patients at the time of their symptoms. Patients who have a small plaque that is ruptured, leading to intracoronary thrombosis and ischemia, will manifest ischemia on diagnostic testing that could missed in routine outpatient testing when their plaque were stable. The diagnosis and risk stratification of acute coronary ischemia in the ED depends on a careful history and interpretation of the ECG. Multiple regression models using readily available data (e.g., history, physical examination, and ECG) provide the best tools for risk stratification. If one is deciding how to select patients for an EDOU chest pain evaluation, diagnostic tools that have previously been tested and validated in this setting are preferable. These include the Multicenter Chest Pain Study derived tools (i.e., Goldman, Lee), the ACI and ACI-TIPI tools, and sestamibi risk stratification tools. This is not to say that other tools may not play a role at individual institutions. It is probably better to select a consistent approach and evaluate its performance, rather than to allow random variation to dictate practice. The future direction probably will involve standardization of the ED chest pain population. This allows outcome and cost-effectiveness comparative research of various strategies for patients with normal or nondiagnostic ECGs and normal biomarkers. Although this approach allows more precise stratification, the risk will never be zero, meaning that there will never be a substitute for good clinical judgment and close follow-up care.

Early use of coronary angiography and intervention

In this article we have outlined the current rationale and role of invasive management in ACS. For the majority of patients with ACS, who are either at high risk or unstable, invasive management is a critical element in breaking the sequence of recurrent ischemia leading to early cardiac events (Fig. 11). Secular trends in the care of cardiovascular patients predict even more sophisticated, invasive methods of treating coronary occlusion in the future. A futurist's view on this subject may envision the following type of scenario. A patient with prior CAD experiences persistent chest pain and notifies the emergency medical system. The paramedics arrive, and perform a rapid fingerstick cardiac biomarker panel and ECG. The results are interpreted by an emergency physician via a telecommunication system, and the patient is determined to be at high risk. He or she is triaged to a center capable of angioplasty and bypass surgery. On the way to the hospital, the patient is treated with aspirin, IV heparin, and an IV glycoprotein IIb/IIIa inhibitor. The patient undergoes triage angiography within 1 hour of hospital arrival, culprit lesion(s) are identified, and a revascularization plan is made--setting a critical pathway that is definitive. This vision is not far off on the horizon. We anticipate additional clinical trial results will help form the decision points in this optimal treatment scenario, which for a large proportion of patients will involve invasive management.

Clinical predictors of in-hospital prognosis in unstable angina: ECLA 3. The ECLA Collaborative Group

OBJECTIVES

Because of recent changes in the treatment of unstable angina, we wanted to reassess the short-term prognostic value of clinical and echocardiographic variables.

METHODS

This was an observational, prospective study that included 1038 nonselected consecutive patients admitted to coronary care units for unstable angina.

RESULTS

Baseline characteristics were age 60.18 +/- 16 years, history of prior myocardial infarction in 336 patients (32%), and a history of previous angina in 817 patients (78.7%). Angina during the 48 hours before admission was observed in 1004 patients (96.7%) and ST-segment changes on admission electrocardiogram occurred in 385 patients (37%). In-hospital treatment consisted of nitrates in 81.4% of patients, aspirin in 88.6%, beta-blockers in 71%, intravenous heparin in 34.5%, subcutaneous heparin in 23%, and angioplasty or coronary artery bypass grafting in 25.1%. After admission, angina occurred in 443 patients (40.8%), refractory angina in 223 patients (21.5%), and death or myocardial infarction in 84 patients (8.1%). At admission, the independent predictors of myocardial infarction or death identified by multivariate logistic regression analysis were ST-segment depression (odds ratio [OR] 2.13, 95% confidence interval [CI] 1.23 to 3.68, P =.006), prior angina (OR 2.23, 95% CI 0.98 to 5.05, P =.05), number of episodes of angina within the previous 48 hours (OR 1.63, 95% CI 0.98 to 2.70, P =.05), and history of smoking (OR 0.69, 95% CI 0.56 to 0.85, P =.004). Age greater than 65 years (OR 1.49, 95% CI1.09 to 2.03, P = 0.03) was significantly related to in-hospital death. The area under the receiver operating characteristic curve for application of this model was 0.59. Sensitivity was 80% with a specificity of only 33%. Refractory angina after admission showed a strong relation with an adverse short-term outcome.

CONCLUSIONS

With current therapy, clinical and electrocardiographic variables provide useful information about the short-term outcome of unstable angina. However, this model has low specificity to identify high-risk patients. Future studies about the incremental value of the new serum markers such as troponin T and C-reactive protein to assist in identification of high-risk patients are necessary.

Potential impact of evidence-based medicine in acute coronary syndromes: insights from GUSTO-IIb. Global Use of Strategies to Open Occluded Arteries in Acute Coronary Syndromes trial

OBJECTIVES

The purpose of this study to determine whether use of cardiac medications reflects evidence-based recommendations for patients with non-ST elevation acute coronary syndromes.

BACKGROUND

Agency for Health Care Policy and Research practice guidelines for unstable angina recommend the use of cardiac medications based on evidence from randomized trials. It is unknown whether practitioners in the U.S., Canada and Europe follow these recommendations in patients with non-ST elevation acute coronary syndromes.

METHODS

We studied 7,743 patients with non-ST elevation acute coronary syndromes enrolled in the international Global Use of Strategies to Open Occluded Arteries in Acute Coronary Syndromes trial. The use of aspirin, beta-adrenergic blocking agents, angiotensin-converting enzyme inhibitors and calcium channel blocking agents was determined at discharge for all patients and "ideal" patients (those with indications and no contraindications). Using published estimates of relative mortality reductions with these drugs, we calculated the lives that could have been saved at 1 year if discharge medication use had better matched guideline recommendations.

RESULTS

Overall, guideline adherence at discharge in "ideal" patients was 85.6% for aspirin, 59.1% for beta-blockers and 51.7% for angiotensin-converting enzyme inhibitors. Calcium channel blockers were given to 26.7% of patients with a contraindication to these drugs. These rates were similar across locations of enrollment. Women and older patients less often received aspirin when "ideal," and younger patients more often received calcium channel blockers when they were contraindicated. If medication use had been more evidence-based, 1-year mortality might have been reduced by a relative 22%.

CONCLUSIONS

There is significant room for improvement in the use of recommended drugs in patients with non-ST elevation acute coronary syndromes. Medication use that more closely follows recommendations could reduce mortality in this population.

Evaluation and risk stratification of patients with chest pain in the emergency department. Predictors of life-threatening events

While assessing chest pain in the emergency department, physicians must first estimate the probability of acute ischemic states in the patient. This first estimate is based on the patient's history, physical examination, and electrocardiogram. Patients who meet the threshold for acute cardiac ischemia are further evaluated to confirm or exclude this diagnosis, while other life-threatening factors are excluded.

Histological patterns of atherosclerotic plaques in unstable angina patients vary according to clinical presentation

BACKGROUND

Unstable angina is a heterogeneous clinical syndrome. The diverse clinical presentations of unstable angina may reflect different pathogenic mechanisms within the plaque.

OBJECTIVE

To investigate the cellular constituents of culprit coronary atheromatous plaques in patients with stable angina pectoris and patients with diverse clinical presentations of unstable angina.

METHODS

48 patients who underwent coronary atherectomy for management of ischaemic heart disease: 23 had stable angina and 25 had unstable angina. Of the latter, 11 patients were classified as Braunwald's IIB and 14 as Braunwald's IIIB unstable angina. The presence of thrombus, cholesterol clefts, and smooth muscle cell proliferation was assessed in atherectomy samples using standard histological techniques. Monoclonal antibodies were used to identify smooth muscle cells and macrophages within atherosclerotic plaque fragments.

RESULTS

Fresh thrombus was more frequently found in patients with Braunwald's IIIB unstable angina (64%) than in patients with stable angina (22%) or IIB unstable angina (27%) (p < 0.0006). A pattern of smooth muscle cell proliferation ("accelerated progression pattern") was observed which was also associated with coronary thrombus. This pattern was present in 30% of patients with stable angina, 64% of patients with IIIB unstable angina, and in all patients (100%) with IIB unstable angina. Atherosclerotic plaques with thrombus, cholesterol clefts, and macrophages were more common in patients with unstable angina than in stable angina patients.

CONCLUSION

The presence of a specific smooth muscle cell proliferation (accelerated progression) pattern in patients with unstable angina, particularly in those with Braunwald's IIB unstable angina, suggests that episodic plaque disruption and subsequent healing may be an important mechanism underlying angina symptoms in these patients.

Clinical and echocardiographic correlates of health status in patients with acute chest pain

OBJECTIVE

To assess the ability of echocardiographic data to predict important functional status outcomes in patients with chest pain.

DESIGN

Prospective cohort study.

SETTING

A large, urban teaching hospital.

PATIENTS

Three hundred thirty-three patients admitted from the Emergency Department for evaluation of chest pain.

MEASUREMENTS AND MAIN RESULTS

Patients underwent two-dimensional and Doppler echocardiography as well as a face-to-face interview during their initial hospitalization and a telephone interview 1 year thereafter. The interview included the Medical Outcomes Study 36-Item Short Form (SF-36) health inventory, a generic health status instrument with a physical function subscale. The relation between clinical and echocardiographic factors and functional status was explored by univariable and multivariable linear regression and logistic regression analyses. Multiple clinical and echocardiographic factors correlated significantly with functional status measures at 1 year. For the SF-36 score at 1 year, age, male gender, white race, the presence of rales, and a comorbidity score were independently predictors in multivariate analysis; echocardiographic findings of severe left ventricular dysfunction (parameter estimate [PE] -27.6; 95% confidence interval [CI] -43.1, -12.2) and aortic insufficiency (PE -16.7; 95% CI -26.4, -7.0) added independent predictive information. Explanatory power (r2) for models using clinical and demographic variables was .27 and increased after inclusion of echocardiographic data to an r2 of .35. Results in the subset of patients (n = 148) with acute coronary syndromes such as unstable angina or myocardial infarction were qualitatively similar. Selected factors (rales on examination, electrocardiographic changes suggestive of ischemia, and moderate to severe mitral regurgitation) also predicted which patients would die or have a decline in their functional status. In multivariate analysis, only rales remained an independent predictor of poor outcome (odds ratio 2.4; 95% CI 1.2, 4.5).

CONCLUSIONS

Echocardiographic data are correlated with measures of functional status in patients with chest pain, but the ability to predict future functional status from clinical or echocardiographic information is limited. Because functional status cannot be predicted adequately from either patients' characteristics or echocardiographic testing, it must be assessed directly.

Impact of valvular regurgitation and ventricular dysfunction on long-term survival in patients with chest pain

Doppler echocardiography is often used in evaluating patients with chest pain, but information on prognostic value of this testing and data to help guide selective use are limited. We prospectively studied 448 patients admitted from the emergency department for acute chest pain to assess the utility of qualitative echocardiographic data in predicting long-term survival and the incremental value of this information over routine clinical and electrocardiographic data. Doppler echocardiograms, recorded an average of 21 hours after presentation, were analyzed independently by 2 echocardiographers for global left and right ventricular function and valvular disease. Regional function was assessed by wall motion index. Data on long-term survival were collected with an average follow-up of 35.0 +/- 12.1 months. In univariate Cox regression analysis, left ventricular function and size, wall motion index, right ventricular function, and aortic, mitral, and tricuspid insufficiency were significant predictors of total and cardiovascular mortality. In multivariate analysis, moderate or severe left ventricular dysfunction (mortality rate ratio 3.2, 95% confidence intervals 1.8 to 5.8] and more than mild valvular regurgitation (mortality rate ratio 2.0, 95% confidence interval 1.1 to 3.6) were independent predictors of mortality in a model adjusted for clinical and electrocardiographic data. These factors were more common in patients aged >60 years, in those with prior acute myocardial infarction or angina, and in those with rales on physical examination. In the absence of these clinical characteristics, only 8 of 124 patients (7%) had moderate or severe left ventricular dysfunction or valvular regurgitation. In patients with moderate or severe regurgitation, a murmur was noted on the admission physical examination in 41 of 69 cases (59%). We conclude that echocardiographic evidence of moderate or severe left ventricular dysfunction or valvular regurgitation identifies a high-risk group for overall and cardiovascular mortality in patients with chest pain, and this evidence may not be detected clinically.

Early prediction of risk in patients with suspected unstable angina using serum troponin T

BACKGROUND

One-third of patients with rest angina are reported to have detectable cardiac troponin T in the serum and may be at increased risk of serious cardiac events.

AIM

To investigate whether a single early estimation of serum troponin T was an independent predictor of serious cardiovascular complications in patients with suspected unstable angina.

METHODS

A prospective cohort study in which patients with suspected rest angina had a serum troponin T estimation 14 hours after symptom onset and were classified using discriminator levels of serum troponin T of 0.05 and 0.1 microgram/L as well as a number of other variables. All patients were followed for six months to document any cardiac complications and a stepwise logistic regression analysis was conducted to determine independent risk factors of complications.

RESULTS

One hundred and sixty-four patients were evaluated. Using a discriminator level of 0.05 microgram/L 54 patients (33%) had detectable troponin T. The admission ECG was the only independent predictor of cardiac events in hospital--odds ratio 4.0 (95% CI 1.7-9.6). Detectable troponin T did not appear to be an independent predictor of serious complications. During the six-month follow-up period, detectable troponin T using a discriminator of 0.05 microgram/L was an independent predictor of serious complications--odds ratio 3.7 (95% CI 1.8-7.6).

CONCLUSIONS

In patients with suspected rest angina, detectable serum troponin T > 0.05 microgram/L is an independent predictor of serious cardiac events during the six-month follow-up period although not during hospitalisation. Using a single, early serum troponin T estimation and other variables available at the time of admission, a high risk subgroup who may benefit from early investigation and revascularisation can be identified.

Cost-effectiveness of a coronary care unit versus an intermediate care unit for emergency department patients with chest pain

BACKGROUND

Guidelines are not available for which patients with acute chest pain should be admitted to the coronary care unit and which patients can be reasonably triaged to monitored beds in lower levels of care.

METHODS AND RESULTS

Clinical and resource utilization data from 12 139 emergency department patients with acute chest pain were used in a decision-analytic model to identify cost-effective guidelines for the admission to a coronary care unit versus an intermediate care unit for initially uncomplicated patients without other indications for intensive care. The probability of clinical complications and death were derived from data on age-specific subsets of the population. Resource utilization estimates were based on cost data from a subset of 901 patients and length of stay data for the entire cohort. The survival benefit associated with initial triage to the coronary care unit instead of an intermediate care unit was assumed to be 15%. In the baseline analysis for 55- to 64-year-old patients, the probability of acute myocardial infarction (AMI) at which the coronary care unit had an incremental cost-effectiveness below $50 000 per year-of-life-saved was 29%. Triage to the coronary care unit was somewhat more cost-effective in elderly patients because their higher early complication rate more than offset their shorter life expectancy.

CONCLUSIONS

This analysis indicates that the coronary care unit usually should be reserved for patients with a moderate (21% or more, depending on the patient's age) probability of AMI unless patients need intensive care for other reasons. Clinical data suggest that only patients with ECG changes of ischemia or infarction not known to be old have a probability of AMI this high. Intermediate care units are appropriate for patients whose risks are not high enough for a coronary care unit to be cost-effective but too high for other alternatives to be recommended for safety and effectiveness.

Unstable angina pectoris

Preview Patients with angina that occurs increasingly often, for longer periods, with less and less exertion, or during periods of rest are of particular concern. These traits are all characteristic of unstable angina. Unlike stable angina, which has a relatively benign course, unstable angina has the capability of progressing to acute myocardial infarction or death. The authors summarize patient evaluation, with emphasis on identification of those at risk.

Outcome of patients with diabetes and unstable angina. A subgroup analysis in the Spanish Multicentre Trial of trifusal in unstable angina. Grupo de Estudio del Trifusal en la Angina Inestable

We analyzed the clinical characteristics of the 58 diabetic and 218 nondiabetic patients enrolled in the Spanish multicentre trial of trifusal in unstable angina. After 6 months of follow-up, 25 suffered from myocardial infarction or death, 10 of which were diabetics (17.2%) and 15 nondiabetics (6.9%) (P = 0.0146). This difference remained significant after multivariate analysis. We conclude that diabetes is an independent predictor of adverse outcome in patients with medically treated unstable angina.

Echocardiographic correlates of survival in patients with chest pain

OBJECTIVES

This study sought to identify echocardiographic predictors of survival in patients with chest pain and to assess the utility of qualitative echocardiographic data in the prognostic stratification of this cohort.

BACKGROUND

The potential usefulness of echocardiographic data in prognostic stratification of patients with acute chest pain is unclear, in part because of the qualitative nature of routinely available echocardiographic readings.

METHODS

The study group comprised 513 patients who underwent transthoracic two-dimensional and Doppler echocardiography within 1 month of emergency department visits for acute chest pain. Clinical and electrocardiographic (ECG) data were recorded for these patients at the time of their initial evaluations, and echocardiographic data were subsequently obtained from the official hospital reports. Follow-up survival rate data were obtained from medical records or the Massachusetts Bureau of Vital Statistics.

RESULTS

A mean of 28.5 months after the index visit, 102 patients (20%) had died, including 58 (57%) for whom the primary cause of death was cardiovascular. In analysis of routinely available qualitative echocardiographic data, left ventricular size and function, the presence of regional wall motion abnormalities, mitral regurgitation and structural abnormalities of the mitral valve were significant univariate correlates of both overall mortality and death from cardiovascular causes. Severe left ventricular dysfunction (adjusted rate ratio 3.8, 95% confidence interval [CI] 1.9-7.5) and moderate or severe mitral regurgitation (adjusted rate ratio 2.4, 95% CI 1.5-3.7) were independent predictors of mortality in a multivariate Cox regression analysis that adjusted for clinical and ECG variables. Moderate or severe left ventricular dysfunction and mitral regurgitation were predictors of mortality in the subset of patients without acute myocardial infarction.

CONCLUSIONS

Qualitative echocardiographic reports of left ventricular dysfunction and mitral regurgitation were independent correlates of prognosis in patients with acute chest pain, including patients without acute myocardial infarction. Further data are needed to assess the generalizability of these findings and the implications for use of this diagnostic technology.

Modern approaches to the diagnosis of coronary artery disease

Atherosclerotic coronary artery disease is a serious clinical problem. Clinicians dealing with patients can make a diagnosis of coronary disease in several ways. Unfortunately all too often the diagnosis is made via sudden death or acute myocardial infarction. At other times the diagnosis is made by evaluation of patients with symptoms--usually symptoms of angina or anginal equivalents. The great clinical and epidemiologic challenge of the coming years is to recognize that education and evaluation of persons with no symptoms or signs of coronary disease, but with risk factors for it, can and should be a focus of major efforts to reduce the number one cause of death in our society.

Value and limitations of current methods of evaluating patients presenting to the emergency room with cardiac-related symptoms for determining long-term prognosis

The goal of this study was to determine the value and limitations of the current approach for evaluating patients in the emergency room (ER) with cardiac-related symptoms in terms of predicting long-term outcome. Accordingly, 274 consecutive prospectively identified patients presenting to the ER with such symptoms were evaluated, and follow-up was obtained at 20 +/- 9 months in 265 of them (97%). Adverse cardiovascular events were defined as: nonfatal myocardial infarction, death, cerebrovascular accident with neurologic deficit, life-threatening arrhythmia and cardiac surgery. Eighty-three patients (31%) had a cardiovascular event during follow-up; 42 occurred within 48 hours of ER presentation, whereas 41 occurred in the ensuing months. Findings on physical examination and electrocardiogram provided additional prognostic information, compared with that of history alone, when added sequentially into a Cox model. However, by discriminant function analysis, only 63% of actual events were correctly predicted by the model. Events occurring after 48 hours of ER presentation were correctly predicted only 50% of the time compared with those occurring within 48 hours of ER presentation, which were correctly predicted 75% of the time (p = 0.04). It is concluded that patients presenting to the ER with cardiac-related symptoms are at high risk for adverse cardiovascular events. The likelihood of an event occurring after 48 hours of presentation is as high as one occurring within 48 hours. Current methods of evaluating such patients have limited prognostic value, particularly for those at long-term risk for events.

Long-term survival of emergency department patients with acute chest pain

To evaluate the long-term prognosis of patients with acute chest pain, prospective clinical data and long-term follow-up data (mean 30.1 +/- 9.4 months) were collected for 1,956 patients who presented to the emergency department of an urban teaching hospital with this chief complaint. During follow-up of the 1,915 patients who were discharged alive from the emergency department or hospital, there were 113 (6%) cardiovascular deaths. No differences were detected in the post-discharge cardiovascular survival rates after 3 years of experience with patients who were discharged from the emergency department with a known prior diagnosis of angina or myocardial infarction (89%) and patients who had been admitted and found to have acute myocardial infarction (85%), angina (87%), or other cardiovascular diagnoses (87%). Patients who were discharged from either the hospital or the emergency department without cardiovascular diagnoses had an excellent prognosis. Multivariate Cox regression analysis identified 5 independent correlates of cardiovascular mortality after discharge: age, prior history of coronary disease, ischemic changes on the emergency department electrocardiogram, congestive heart failure and cardiogenic shock. These findings indicate that the postdischarge cardiovascular mortality of patients with chest pain who are discharged from the emergency department with a known history of coronary disease is similar to that of admitted patients with angina or myocardial infarction. These data suggest that the same types of prognostic evaluation strategies that have been developed for admitted patients with ischemic heart disease should also be considered when such patients present to the emergency department but are not admitted.

Frequency of use of thrombolytic therapy in acute myocardial infarction in Israel

Thrombolysis is now generally accepted as the initial treatment for patients with acute myocardial infarction (AMI). The extent to which this therapy is implemented in daily practice and the reasons for exclusion from thrombolytic therapy among 413 consecutive patients with AMI hospitalized in 18 coronary care units in Israel during a 1-month survey were prospectively investigated. Thrombolytic therapy administered to 145 patients (35%) was given to 38% of men versus 29% of women (p = not significant), to 38% of patients less than 75 years old compared with 18% of the very elderly (p less than 0.005), and more often to patients with a first or anterior AMI (40 and 48%) than to counterparts with recurrent or inferior AMI (23 and 31%, respectively, p less than 0.005 for both). The 2 most frequent reasons for excluding patients from thrombolysis were late arrivals to coronary care units (33%) and lack of ST elevation on the admission electrocardiogram (28%). Hospital mortality was 6% in the thrombolytic group versus 20% in patients found ineligible for thrombolysis. The significance of this difference is not clear as treatment was not randomized.

Impact of physician experience on triage of emergency room patients with acute chest pain at three teaching hospitals

PURPOSE

To determine whether the experience of the physician (as measured by postgraduate training level or time during the academic year) who performs the initial evaluation affects the triage of patients with acute chest pain.

PATIENTS AND METHODS

Prospective data on the presenting clinical features, initial triage, final diagnosis, and complications were collected for 7,857 patients who presented to the emergency rooms of three teaching hospitals, including 1,118 (14%) with acute myocardial infarction (AMI), 2,477 (32%) with acute ischemic heart disease (AIHD) (i.e., AMI or unstable angina), and 335 (4%) with major complications. The experience of the evaluating physicians, who were in their first three postgraduate years in 93% of cases, was measured in three ways: (1) postgraduate training level, (2) month during the academic year, and (3) number of patients with acute chest pain previously evaluated. Multivariate logistic regression analyses that adjusted for hospital site and 20 clinical variables estimated the odds ratios for admission to the coronary care unit (CCU) and hospital associated with each incremental increase in physician experience.

RESULTS

With more experience (as measured by postgraduate training level or time during the academic year), the sensitivity of physicians for admitting patients with AMI, AIHD, or major complications to the hospital increased. For example, each incremental increase in postgraduate training level carried a 1.4 increase in the adjusted odds ratio for admission of a patient with AIHD to the hospital (p less than 0.05), corresponding to an increase in the probability of admission from 93% to 97%. However, increasing physician experience was also associated with an elevated false-positive rate in admitting patients without these diagnoses to the CCU and hospital. Thus, each incremental increase in postgraduate training level carried a 1.2 increase in the adjusted odds ratio for admission of a patient without AIHD to the CCU and hospital (p less than 0.005), corresponding to an increase in the probability of admission from 34% to 47%. By receiver operating characteristic curve (ROC) regression analyses, these changes in triage patterns were consistent with movement along a single ROC curve, rather than a shift to a new or better ROC curve.

CONCLUSIONS

As the experience of the physician who performed the initial evaluation increased, there was a lower threshold for admitting all patients with and without AMI, AIHD, or major complications to the CCU and hospital without a detectable improvement in diagnostic accuracy.

Ruling out acute myocardial infarction. A prospective multicenter validation of a 12-hour strategy for patients at low risk

BACKGROUND

Although previous investigations have suggested that 24 hours is required to exclude acute myocardial infarction in patients who are admitted to a coronary care unit for the evaluation of acute chest pain, we hypothesized that a 12-hour period might be adequate for patients with a low probability of infarction at the time of admission.

METHODS

Using a Bayesian model, we developed a strategy to identify candidates for a shorter period of observation from an analysis of a derivation set of 976 patients with acute chest pain who were admitted to three teaching and four community hospitals. In the derivation set, patients whose clinical characteristics in the emergency room predicted a low (less than or equal to 7 percent) probability of myocardial infarction had only a 0.4 percent risk of infarction if they had neither abnormal levels of cardiac enzymes nor recurrent ischemic pain during the first 12 hours of hospitalization. In an independent testing set of 2684 patients from the seven hospitals, 957 admitted patients (36 percent) were classified as candidates for this 12-hour period of observation according to a previously published multivariate algorithm. Few of these patients were actually transferred from a monitored setting at 12 hours.

RESULTS

Of the 771 candidates for a 12-hour period of observation who did not have enzyme abnormalities or recurrent pain during the first 12 hours, 4 (0.5 percent) were subsequently found to have acute myocardial infarction, and only 3 (0.4 percent) died after primary cardiac arrests, all of which occurred three to five days after admission. Rates of other major cardiovascular complications were low in the patients who might have been transferred from the coronary care unit after 12 hours with this strategy. In patients with a higher initial risk of infarction, the standard strategy of 24-hour observation identified all but 11 of 739 acute myocardial infarctions (1 percent).

CONCLUSIONS

Emergency room clinical data can be used to identify a large subgroup of patients for whom a 12-hour period of observation is normally sufficient to exclude acute myocardial infarction. Patient-specific evaluation and treatment can then proceed without the restrictions imposed by "rule-out" protocols for myocardial infarction.

Impact of the availability of a prior electrocardiogram on the triage of the patient with acute chest pain

STUDY OBJECTIVE

To determine whether information from a prior electrocardiogram (ECG) improves diagnostic accuracy in the emergency department (ED) evaluation of patients with acute chest pain.

DESIGN

Analysis of prospectively collected data from a cohort study.

SETTING

Emergency departments of four community and three university hospitals.

PATIENTS

5,673 patients aged greater than or equal to 30 years who presented to the EDs of participating hospitals for evaluation of acute chest pain, including 772 (14%) with acute myocardial infarction (AMI).

MEASUREMENTS AND MAIN RESULTS

After adjusting for clinical characteristics, no significant difference was found in the sensitivities of admission to the hospital or to the coronary care unit (CCU) between AMI patients with and without prior ECGs available for review. However, non-AMI patients with prior ECGs available for review were more likely to avoid CCU admission than were non-AMI patients without prior ECGs. This improvement in specificity was most marked in the 2,024 patients whose current ED ECGs had changes consistent with ischemia or infarction: when a prior ECG was available, non-AMI patients were more than twice as likely to be discharged (26% vs. 12%) and about 1.5 times as likely to avoid CCU admission (39% vs. 27%) (both p less than 0.0001). Admission rates of AMI patients with and without prior ECGs were similar.

CONCLUSION

When the current ECG is consistent with ischemia or infarction, the availability of a prior ECG for comparison to determine whether the ECG changes are old or new improves diagnostic accuracy and triage decisions by reducing the admission of patients without AMI or acute ischemic heart disease (increased specificity) without reducing the admission of patients with these diagnoses (unchanged sensitivity).