In June 2018, the ACEP Board of Directors approved a clinical policy on the evaluation and management of adult patients presenting with suspected non–ST-elevation acute coronary syndrome (NSTE ACS).1 In its complete form, this policy can be found on the ACEP website .
Emergency physicians routinely rule out ACS in patients presenting with chest pain and have become very good at targeting timely interventions in the obvious cases of ST-elevation myocardial infarction but still miss up to 2 percent of acute myocardial infarctions, particularly those with non–ST-elevation myocardial infarction (NSTEMI). The purpose of this policy was to focus on the initial diagnosis and treatment of patients who present with potential NSTE ACS.
In developing the policy, the ultimate outcome measure was the 30-day incidence of major adverse cardiovascular event (MACE). This includes cardiovascular death and myocardial infarction, as well as what some argue is more subjective in terms of actual need, coronary revascularization. Most emergency physicians strive to attain a miss rate of less than 1 percent. However, it is questionable if the benefits of further testing outweigh the risks of harm of untreated disease once that threshold reaches 2 percent, which the committee felt was a more realistic expectation. With shared decision making, patients may be willing to accept rates higher than those to which physicians hold themselves accountable.
Emergency departments are so often congested with patients awaiting serial testing (laboratory and noninvasive) to rule out potential ACS that entire units have been dedicated to observing these patients, yet there is questionable benefit. Researchers have been looking for diagnostic strategies, single or serial troponins, and ECGs to try to identify at-risk patients sooner and expedite their transition of care. One strategy adopted internationally and slowly taking hold in the United States is the advent of high-sensitivity troponins. Although these have great promise for detecting potential disease sooner, without proper protocols, they can lead to excessive false positives. Regardless, their use holds great promise in expediting the care of patients suspected of NSTE ACS.
Ultimately, the purpose of this policy was to help ED clinicians expedite the care of patients presenting with chest pain who are at risk for NSTE ACS. The first three questions focus on initial identification of patients at low risk for MACE, using history and limited testing. Are there patients with suspected ACS who are safe to discharge based on initial risk stratification? Do serial troponins really help, and how long do we have to wait to do that second troponin? Does getting early non-invasive diagnostic testing for ACS prior to discharge from the emergency department really help decrease MACE rates? The goal was to see if there were strategies to expedite the initial evaluation and discharge of these patients without resorting to prolonged ED stays (four to six hours or longer) while still limiting the number of 30-day MACE.