Donald A. Brand

A computer protocol to predict myocardial infarction in emergency department patients with chest pain.

To achieve more appropriate triage to the coronary care unit of patients presenting with acute chest pain, we used clinical data on 1379 patients at two hospitals to construct a simple computer protocol to predict the presence of myocardial infarction. When we tested this protocol prospectively in 4770 patients at two university hospitals and four community hospitals, the computer-derived protocol had a significantly higher specificity (74 vs. 71 percent) in predicting the absence of infarction than physicians deciding whether to admit patients to the coronary care unit, and it had a similar sensitivity in detecting the presence of infarction (88.0 vs. 87.8 percent). Decisions based solely on the computer protocol would have reduced the admission of patients without infarction to the coronary care unit by 11.5 percent without adversely affecting the admission of patients in whom emergent complications developed that required intensive care. Although this protocol should not be used to override careful clinical judgment in individual cases, the computer protocol for the most part yields accurate estimates of the probability of myocardial infarction. Decisions about admission to the coronary care unit based on the protocol would have been as effective as those actually made by the unaided physicians who cared for the patients, and less costly. Whether physicians who are aided by the protocol perform better than unaided physicians cannot be determined without further study.

Clinical characteristics and natural history of patients with acute myocardial infarction sent home from the emergency room

In a prospective multicenter investigation of emergency room patients with acute chest pain, physicians admitted 96% of patients with acute myocardial infarction (AMI) and discharged 4%. Of 35 patients who were sent home with AMI, only 11 (31%) returned to the same hospital because of persistent symptoms. Compared with a control group of 105 randomly selected patients with AMI who were admitted from the emergency room, patients in whom AMI was missed were significantly younger, had less typical symptoms and were less likely to to have had prior AMI or angina or to have electrocardiographic evidence of ischemia or infarction not known to be old. Despite the less typical presentations of patients in whom AMI was missed, after controlling for age and sex, the short-term mortality rate was significantly higher among patients in whom AMI was missed but in whom it was detected through our follow-up procedures than in admitted AMI patients. As determined by independent reviewers, 49% of the missed AMIs could have been diagnosed through improved electrocardiographic reading skills or by admission of patients with recognized ischemic pain at rest or ischemic electrocardiographic changes not known to be old.

Prediction of the Need for Intensive Care in Patients Who Come to Emergency Departments with Acute Chest Pain

BACKGROUND Patients who come to the emergency department with chest pain are a heterogeneous group. Some have ischemic heart disease that may lead to serious complications, whereas others have minor disorders. We performed a study to identify clinical factors that predict which patients will have complications requiring intensive care. METHODS We first studied 10,682 patients with acute chest pain at seven hospitals between 1984 and 1986 (derivation set) to identify potential clinical predictors of the development of major complications. We then validated these predictors in a separate set of 4676 patients at one hospital between 1990 and 1994 (validation set). RESULTS In the derivation set of patients, we identified the following set of clinical features, which, if present in the emergency department, were associated with an increased risk of complications: ST-segment elevation or Q waves on the electrocardiogram thought to indicate acute myocardial infarction, other electrocardiographic changes indicating myocardial ischemia, low systolic blood pressure, pulmonary rales above the bases, or an exacerbation of known ischemic heart disease. On the basis of these criteria, the patients in the validation set were stratified into four groups, with the risk of major complications in the first 12 hours ranging from 0.15 to 8 percent. After 12 hours, the probability of a major complication could be updated on the basis of whether the patient had already had a complication of major severity, a complication of intermediate severity, or a myocardial infarction (independent relative risks, 18.9, 7.7 and 4.0, respectively, as compared with patients without prior complications or myocardial infarction). CONCLUSIONS The risk of major complications in patients with acute chest pain can be estimated on the basis of the clinical presentation and new clinical observations made during the hospital course. These estimates of risk help in making rational decisions about the appropriate level of medical care for patients with acute chest pain.

Use of the initial electrocardiogram to predict in-hospital complications of acute myocardial infarction.

Abstract We evaluated the initial electrocardiogram as a predictor of complications in 469 patients with suspected acute myocardial infarction. An electrocardiogram was classified as positive if it showed one or more of the following: evidence of infarction, ischemia, or strain; left ventricular hypertrophy; left bundle-branch block; or paced rhythm. Forty-two (14 per cent) of 302 patients with positive electrocardiograms had at least one life-threatening complication (ventricular fibrillation, sustained ventricular tachycardia, or heart block), as compared with 1 (0.6 per cent) of 167 patients with a negative electrocardiogram. Life-threatening complications were therefore 23 times more likely if the initial electrocardiogram was positive (P<0.001). Other complications were 3 to 10 times more likely (P<0.01), interventions were 4 to 10 times more likely (P<0.05), and death was 17 times more likely (P<0.001) in patients with a positive electrocardiogram. We conclude that patients with a negative initial e...

Clinical Characteristics and Outcome of Acute Myocardial Infarction in Patients with Initially Normal or Nonspecific Electrocardiograms (A Report from the Multicenter Chest Pain Study)

To determine the prevalence and characteristics of acute myocardial infarction (AMI) patients who present to emergency departments with normal or nonspecific electrocardiograms (ECGs), data were analyzed from 7,115 consecutive patients in the Multicenter Chest Pain Study. AMI patients with normal or nonspecific initial ECGs (n = 107) were less likely to have a past history of coronary artery disease or to be diaphoretic on presentation (p less than 0.01) than AMI patients with initial ECGs highly suggestive of AMI (n = 811). The overall probability of AMI among patients with chest pain and initially normal or nonspecific ECGs was 3%, but ranged from less than 1 to 17% depending on the patients age and sex and whether the patient had pressure-type pain or pain radiating to the shoulder, neck or arms. Among initially admitted patients, the time elapsed between onset of pain and presentation was similar in both groups. However, the time between onset of pain and definitive diagnosis of AMI by enzymes or clinical course was longer in patients with initially normal or nonspecific electrocardiograms (8.3 vs 7.5 hours, p less than 0.05), their peak creatine kinase levels were lower (mean 643 vs 1,032 mg/dl, p less than 0.001) and their mortality was slightly lower (6 vs 12%, p = 0.10). These findings suggest that AMI patients with initially normal or nonspecific ECGs may have a less severe short-term clinical outcome.

Sensitivity of routine clinical criteria for diagnosing myocardial infarction within 24 hours of hospitalization.

Myocardial infarction was diagnosed in 431 (30%) of 1460 patients with acute chest pain who had serial enzyme testing after admission to intensive or intermediate care units at three teaching and three community hospitals. The diagnosis was made within 12 hours of admission in 331 (77%) patients and within 24 hours in 415 (96%). Of the 16 patients with myocardial infarction who did not have enzyme abnormalities within 24 hours, 9 (56%) had recurrent ischemic pain during this 24-hour period. Of 451 patients who had neither enzyme abnormalities nor recurrent ischemic pain in the first 24 hours, only 7 (2%) ultimately met diagnostic criteria for myocardial infarction. These findings were prospectively validated in an independent testing set of 275 patients with myocardial infarction, 271 (99%) of whom either met diagnostic criteria for myocardial infarction or had recurrent ischemic pain within 24 hours of admission. These data suggest that 24 hours is nearly always a sufficient period to exclude myocardial infarction in patients without recurrent chest pain.

Candidates for Thrombolysis among Emergency Room Patients with Acute Chest Pain: Potential True- and False-Positive Rates

STUDY OBJECTIVE To assess the potential clinical impact of thrombolytic therapy for acute myocardial infarction by determining true-positive and false-positive rates of criteria for eligibility among emergency room patients with acute chest pain. DESIGN Prospective multicenter cohort study. SETTING Emergency rooms of three university and four community hospitals. PATIENTS Emergency room patients (7734) with acute chest pain. MEASUREMENTS AND MAIN RESULTS Only 261 (23%) of 1118 patients with acute myocardial infarctions were 75 years of age or younger, presented within 4 hours of the onset of pain, and had emergency room electrocardiograms showing probable acute myocardial infarction: 60 (0.9%) of the 6616 patients without infarction also met these criteria (positive predictive value, 261/321 = 81%; CI, 77% to 86%). The positive predictive value could increase to about 88% (CI, 82% to 93%) if eligibility were based on the official hospital electrocardiogram reading. CONCLUSIONS Because experience from published studies suggests that about one third of patients who meet these three eligibility criteria have other contraindications to thrombolysis, we estimate that about 15% of patients with acute myocardial infarction would meet the criteria for eligibility for thrombolysis that have been used in clinical trials at the time of emergency room presentation. Further, for every eight patients with true-positive results who are treated, one to two patients with false-positive results may also be treated if decisions are based on the interpretation of a single electrocardiogram.

The effect of gender on the probability of myocardial infarction among emergency department patients with acute chest pain: a report from the Multicenter Chest Pain Study Group.

Objective: To identify differences in the incidences of myocardial infarction in women and men with chest pain.Design: Prospective multicenter cohort study.Setting: Emergency rooms of three university and four community bospitals.Patients: 7,734 emergency room patients with acute chest pain.Measurements and main results: Myocardial infarction was diagnosed in 10% of the 3,896 women, compared with 19% of the 3,838 men, yielding an age-adjusted relative risk of myocardial infarction for women of 0.54 (95% confidence interval 0.48, 0.60). Physicians were equally adept at admitting women and men with myocardial infarctions, but men without myocardial infarction or unstable angina were significantly more likely to be admitted than were women without these diagnoses. Most clinical and electrocardiographic features indicating a risk of myocardial infarction were present in both women and men, but several high-risk features were less commonly present in women. After adjusting for the other factors that correlate with each patient’s probability of having acute myocardial infarction, the relative risk of myocardial infarction was the same in women as men when the emergency department electrocardiogram showed the classic changes associated with acute myocardial infarction, but the risk was 40% lower in women when such electrocardiographic changes were not present.Conclusions: Clinical features that predict myocardial infarction in men predict myocardial infarction in women to a similar extent. However, female gender is associated with about a 40% lower rate of myocardial infarction except when classic electrocardiographic evidence is present on the emergency department electrocardiogram.

A protocol for selecting patients with injured extremities who need x-rays.

Abstract To help curb excessive radiography, we developed a protocol for selecting patients with injured extremities who need x-ray examination, and we tested the protocol prospectively in 848 pati...

A chest pain clinic to improve the follow-up of patients released from an urban university teaching hospital emergency department

During a 12-month period, 1,045 of 1,554 patients (67%) over age 30 seen in an urban teaching hospital emergency department with acute chest pain were released based on the clinical judgment of the examining physician. Patients who were released were offered follow-up within 24 to 72 hours in a hospital-based chest pain clinic. Of these 1,045 patients, 772 (74%) returned or were contacted by phone, and 29 were directly admitted; 14 had unstable angina, and eight had new myocardial infarctions. Because of its positive impact on the quality of care at an acceptable cost, the Chest Pain Clinic, which was originally instituted as part of a research protocol, has now become part of the routine spectrum of care provided at the University of Cincinnati Medical Center.