Low-risk AMI patients cause concern
Short-term rule-out AMI’ observation justified
Determining which chest pain patients require expensive intensive care and which can be safely sent home is a dilemma faced daily in your emergency department (ED). A short-term acute myocardial infarction (AMI) observation unit may save your facility money by providing ED staff with reliable information on which to base their weighty decisions.
Patients who come to the ED with chest pain are a heterogeneous group. Some have ischemic heart disease that could lead to serious complications, while others have minor noncardiac disorders. The patient at low risk for AMI is the actor in this drama who causes the most concern.
One of the leading causes of expensive malpractice cases in emergency medicine is the chest pain patient who is sent home and subsequently turns out to have a heart attack. To combat that threat and to provide cost-effective treatment, any ED needs a method to cost-effectively stratify patients who present with chest pain into risk levels before admitting them. (See algorithm showing the derivation of four risk groups, p. 129.)
Evidence-based support for the concept of short-term observation of low-risk patients was published last year by way of a study that considered clinical factors that can predict a patient’s need for ongoing hospital care.1 Gregory W. Rouan, MD, an internist at the University of Cincinnati Medical Center was one of a team of investigators who studied more than 10,000 patients with acute chest pain at seven hospitals. The team determined that certain risk factors good predictors of subsequent complications of major or intermediate severity could be quickly identified in the ED, without waiting for enzyme studies. Factors include:
• EKG showing new AMI;
• EKG showing new ischemia;
• systolic blood pressure below 110 mm Hg;
• rales above the bases bilaterally;
• known unstable ischemic heart disease.
No precise risk threshold can uniformly dictate which patients should be admitted from the ED or for how long, but these factors are predictors. Admission to the intensive care unit (ICU) is appropriate for high-risk and even some moderate-risk patients. Those with evidence of AMI or complications should remain there for two to three days. To provide further assistance, the National Heart, Lung, and Blood Institute in Bethesda, MD, has produced guidelines for potential AMI patients. These guidelines pay particular attention to providing thrombolytic therapy. (See Algorithm for Patients with Chest Pain, p. 128.)
Low-risk and very low-risk patients in the ED have far fewer serious complications during the first 24 hours of care, states the study. After the first 12 hours, the early hospital course, including lab studies, becomes more important than the initial clinical presentation for the prediction of subsequent complications.
"We gathered data on patients who presented with chest pain and who seemed to be at risk for myocardial infarction so we could define some clinical variables that stratify patients at higher or lower risk," Rouan says. "Our data were meant to help clinicians define what diagnostic studies could or should be done and how to best manage these patients."
Study authors also comment that length of stay in intensive care can be decreased for cardiac patients when their interventions are determined based on daily conferences, discharge-planning rounds, or active utilization review.
Based on this study’s findings as well as others, managed care organizations often require a 12-hour rule-out AMI observation period for low-risk patients. They are initially placed in outpatient intermediate care units far less expensive than ICUs where they receive continuous EKG monitoring. Patients are frequently re-evaluated for risk, and those with no complications and no recurrent chest pain at 24 hours are discharged.
Reference
1. Goldman L, Cook EF, Johnson PA, 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; 334:1,498-1,504.
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