Safe discharge from the cardiac emergency room with a rapid rule-out myocardial infarction protocol using serial CK-MBmass

Abstract

Objective-To determine whether a new protocol, using a rapid and sensitive CK-MB mass assay and serial sampling, can rule out myocardial infarction in patients with chest pain and decrease their length of stay in the cardiac emergency room without increasing risk. Design-The combined incidence of cardiac death and acute myocardial infarction at 30 days, six months, and 24 months of follow up were compared between patients discharged home from the cardiac emergency room after ruling out myocardial infarction with a CK-MB activity assay in 1994 and those discharged home after a rapid CK-MB mass assay in 1996. Setting-Cardiac emergency room of a large university hospital. Patients-In 1994 and 1996, 230 and 423 chest pain patients, respectively, were discharged home from the cardiac emergency room with a normal CK-MB and an uneventful observation period. Results-The median length of stay in the cardiac emergency room was significantly reduced, from 16.0 hours in 1994 to 9.0 hours in 1996 (p < 0.0001). Mean event rates in patients from the 1994 and 1996 cohorts, respectively, were 0.9% (95% confidence interval (CI) −0.3% to 2.1%) v 0.7% (95% CI −0.1% to 1.5%) at 30 days, 3.0% (95% CI 0.8% to 5.2%) v 2.8% (95% CI 1.2% to 4.4%) at six months, and 7.0% (95% CI 3.7% to 10.3%) v 5.7% (95% CI 3.5% to 7.9%) at 24 months. Kaplan-Meier survival analysis showed no diVerence in mean event-free survival at 30 days, six months, and 24 months of follow up. Conclusions-Using a rule-out myocardial infarction protocol with a rapid and sensitive CK-MB mass assay and serial sampling, the length of stay of patients with chest pain in the cardiac emergency room can be reduced without compromising safety.

Adverse Cardiac Events in Emergency Department Patients with Chest Pain Six Months after a Negative Inpatient Evaluation for Acute Coronary Syndrome

“…One factor explaining the higher rate of ACEs in this study is the inclusion of unstable angina in the composite endpoint, whereas many prior studies examined only rates of death and MI. 6,7,[10][11][12][13]15,[20][21][22][23][24][25] We included unstable angina because these patients have been documented to have a long-term prognosis similar to that of patients with MI. 3,18,23 A broader composite endpoint of ACEs may better detect poor outcomes in this patient population.…”

“…5 Patients with chest pain are at relatively low risk (<7%) for cardiac events within 72 hours if they have a negative workup based on history and ECG findings alone. 2,3 Findings of negative serial cardiac markers in addition can identify a population at even lower risk for cardiac events at 30 days (0.3-0.7%) 6,7 and 60 days (0.2-2.8%). [6][7][8] This population, however, re-mains at relatively high risk of subsequent cardiac morbidity within six months (5-23%).…”

“…2,3 Findings of negative serial cardiac markers in addition can identify a population at even lower risk for cardiac events at 30 days (0.3-0.7%) 6,7 and 60 days (0.2-2.8%). [6][7][8] This population, however, re-mains at relatively high risk of subsequent cardiac morbidity within six months (5-23%). 9,10 Recent prospective studies have investigated the prognosis of patients with nondiagnostic or negative diagnostic cardiac studies.…”

How Safe Is the Outpatient Management of Patients with Acute Chest Pain and Mildly Increased Cardiac Troponin Concentrations?

“…Therefore negative serial cardiac troponin measurements, in addition to clinical assessment, allow for the identification of a population at low risk for cardiac events (6,7 ).…”

Outcome of low-risk patients discharged home after a normal cardiac troponin I

“…Hamm's study, described above, suggested that low-risk patients with a normal EKG and normal cTnI might be safe for discharge (23). Bholasingh et al had very low event rates in 653 chest pain patients sent home after a negative CK-MB (30). No studies that we are aware of report the safety of discharging patients home with a normal troponin, without further observation or provocative testing.…”