Safe discharge from the cardiac emergency room with a rapid rule-out myocardial infarction protocol using serial CK-MB(mass)

Prevalence and prognosis of non-specific chest pain among patients hospitalized for suspected acute coronary syndrome - a systematic literature search

BACKGROUND

The term non-specific chest pain (NSCP) is applied to hospitalized patients in order to designate that they neither have an acute coronary syndrome (ACS) nor display evidence of a coronary ischemia. The number of NSCP patients is increasing and comprehensive guidelines specifying their optimal management have not yet been introduced. The objective of this review was to explore the prevalence and prognosis of NSCP versus ACS among patients recruited in consecutive series hospitalized for chest pain suspected to be ACS.

METHODS

This is a systematic literature search where three databases were searched from 1990 to 14 November 2011. In addition, one database was searched for Epub ahead of print per 24 March 2012. Three inclusion criteria were applied: 1. documentation of an unselected consecutive series of patients admitted for chest pain, where this review is based upon two groups of patients defined as follows: a) 'ACS/high-risk' and b) NSCP; 2. at least 100 cases with NSCP; and 3. follow-up of hospital readmissions and mortality for at least six months.

RESULTS

A total of 2,204 citations were screened after removal of duplicates. Out of 80 full text articles assessed for eligibility 12 studies were included, comprising 24,829 patients (inter-study range 250 to 13,762), with 11,008 (44%) categorized as NSCP and 13,821 (56%) as 'ACS/high-risk'. The mean one-year total mortality rate among patients with NSCP in nine studies was 3.2% (inter-study range 1.4% to 8.1%), with the highest mortality among patients with pre-existing coronary heart disease (CHD). The mean one-year mortality rate among 'ACS/high-risk' patients was 18.0% (inter-study range 14.0% to 19.9%) in four studies with available data. In six studies the mean one-year readmission rate for patients with NSCP was 17.5% (inter-study range 2.5% to 40%).

CONCLUSIONS

Patients with NSCP represent a large, heterogeneous and important group. Due to co-existing CHD in nearly 40% of these patients, their prognosis is not necessarily benign. Although their average one-year mortality rate was almost six times lower than those with 'ACS/high-risk', the subset with concomitant CHD had a relatively poor prognosis when compared with NSCP patients without evidence of CHD.

Cost burden of non-specific chest pain admissions

BACKGROUND

Non-cardiac aetiologies are common among patients presenting with chest pain.

AIM

To determine the cost of non-specific chest pain admissions to a tertiary referral, teaching hospital.

METHODS

Thrombolysis in myocardial infarction risk (TIMI) risk score, lengths of stay (LOS), investigations and diagnoses were recorded for patients admitted with chest pain. Non-specific chest pain was defined as chest pain where cardiac, pulmonary and gastroesophageal aetiologies were excluded. Costs of admissions were calculated.

RESULTS

Of 80 patients, 34 (4%) and 22 (28%) were diagnosed with non-specific chest pain and acute coronary syndrome, respectively. Non-specific chest pain admissions had a mean age of 54 (11; 35-74) years, LOS of 3.8 (2.6; 1-11) days and TIMI risk score of 1.4 (1.5; 0-5). Acute coronary syndrome admissions had a mean age of 67 (14; 43-94) years, LOS of 7.7 (4.3; 2-16) days and TIMI risk score of 3.1 (1.2; 0-5). The mean cost per non-specific chest pain admission was €3,729 (2,378; 1,034-10,468), or 48% of the mean cost per acute coronary syndrome admission of €7,667 (4,279; 1,963-16,071). Bed day costs account for >90% of overall costs. Only 7% of patients were weekend discharges. The mean interval to exercise stress test was 2.7(1.5; 1-7) days.

CONCLUSIONS

The mean costs of admission and LOS for patients with non-specific chest pain are significant. Extrapolating findings, annual national cost is estimated at approximately €71 million for this cohort, with 73,000 bed days consumed nationally. Delays from admission to tests and low percentage of weekend discharges prolong LOS.

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

BACKGROUND

The appropriate management of patients discharged from the emergency department (ED) with increased high-sensitivity cardiac troponin T (hs-cTnT) but normal or borderline-high conventional cardiac troponin concentrations is unknown.

METHODS

We investigated 643 consecutive ED patients with acute chest pain who had been discharged for outpatient management after acute myocardial infarction (AMI) had been ruled out by serial measurements of conventional cardiac troponin. hs-cTnT was measured blindly, and we calculated the rates of all-cause mortality (primary endpoint) and subsequent AMI (secondary endpoint) at 30, 90, and 360 days.

RESULTS

hs-cTnT concentrations were increased (>14 ng/L) in 114 patients (18%) but <30 ng/L in 95% of these patients. Of those 114 patients, 96 (84%) had an adjudicated noncoronary cause of chest pain. Thirty-day mortality (95% CI) was 0.9% (0.1%–6.1%), 90-day mortality was 2.7% (0.9%–8.1%), and 360-day mortality was 5.2% (2.2%–11.9%) in patients with increased hs-cTnT; respective rates (95% CI) of AMI were 0.0%, 1.9% (0.5%–7.2%), and 7.6% (3.7%–15.3%). Increased hs-cTnT was associated with increased mortality and AMI at 90 days (P = 0.006 and P = 0.081, respectively) and 360 days (P = 0.001 for both).

CONCLUSIONS

hs-cTnT is a strong prognosticator of intermediate and long-term mortality and AMI in low-risk patients discharged from the ED after AMI has been ruled out. The relatively low rate of 30-day events may suggest that patients without acute coronary syndrome and small increases in cardiac troponin are in need of further investigations and treatments, but not necessarily immediate hospitalization.

Structure, process and outcomes of chest pain units established in the ESCAPE trial

BACKGROUND

Chest pain units (CPUs) provide a system of care for patients with acute chest pain that can improve outcomes while reducing health service costs. The Effectiveness and Safety of Chest Pain Assessment to Prevent Emergency Admissions (ESCAPE) multicentre trial was undertaken to determine whether CPUs could be successfully established throughout the National Health Service (NHS).

AIM

To describe the structure, processes and outcomes of patients managed by CPUs in the ESCAPE Trial.

METHOD

7 of 14 participating hospitals were randomly allocated to establish CPU care. Each hospital set up a CPU using standardised protocols to provide biochemical cardiac marker and exercise treadmill testing for low-risk patients. Research staff then followed up patients for 30 days to identify any adverse events, defined as chest pain-related readmission to hospital for more than 48 h, non-fatal myocardial infarction and all deaths.

RESULTS

The 7 units managed a total of 1644 patients during their first year of operation. Activity varied from 1 to 7 patients per 1000 adult emergency department attendances. Overall, 1374 (83%) patients were discharged after CPU assessment, with 23 (1.7%) adverse events recorded among those discharged. Some, but not all, of the variation in activity could be attributed to hospital size and patient selection.

CONCLUSION

CPU care can be instituted in a safe manner at a variety of NHS hospitals, with most patients being discharged after assessment. However, there is variation in the number and type of patients managed by the different units. Further research is required to identify reasons for variation in CPU activity.

Which diagnostic tests are most useful in a chest pain unit protocol?

BACKGROUND

The chest pain unit (CPU) provides rapid diagnostic assessment for patients with acute, undifferentiated chest pain, using a combination of electrocardiographic (ECG) recording, biochemical markers and provocative cardiac testing. We aimed to identify which elements of a CPU protocol were most diagnostically and prognostically useful.

METHODS

The Northern General Hospital CPU uses 2-6 hours of serial ECG/ST segment monitoring, CK-MB(mass) on arrival and at least two hours later, troponin T at least six hours after worst pain and exercise treadmill testing. Data were prospectively collected over an eighteen-month period from patients managed on the CPU. Patients discharged after CPU assessment were invited to attend a follow-up appointment 72 hours later for ECG and troponin T measurement. Hospital records of all patients were reviewed to identify adverse cardiac events over the subsequent six months. Diagnostic accuracy of each test was estimated by calculating sensitivity and specificity for: 1) acute coronary syndrome (ACS) with clinical myocardial infarction and 2) ACS with myocyte necrosis. Prognostic value was estimated by calculating the relative risk of an adverse cardiac event following a positive result.

RESULTS

Of the 706 patients, 30 (4.2%) were diagnosed as ACS with myocardial infarction, 30 (4.2%) as ACS with myocyte necrosis, and 32 (4.5%) suffered an adverse cardiac event. Sensitivities for ACS with myocardial infarction and myocyte necrosis respectively were: serial ECG/ST segment monitoring 33% and 23%; CK-MB(mass) 96% and 63%; troponin T (using 0.03 ng/ml threshold) 96% and 90%. The only test that added useful prognostic information was exercise treadmill testing (relative risk 6 for cardiac death, non-fatal myocardial infarction or arrhythmia over six months).

CONCLUSION

Serial ECG/ST monitoring, as used in our protocol, adds little diagnostic or prognostic value in patients with a normal or non-diagnostic initial ECG. CK-MB(mass) can rule out ACS with clinical myocardial infarction but not myocyte necrosis(defined as a troponin elevation without myocardial infarction). Using a low threshold for positivity for troponin T improves sensitivity of this test for myocardial infarction and myocardial necrosis. Exercise treadmill testing predicts subsequent adverse cardiac events.

Acute Myocardial Infarction Following a Negative Evaluation of Chest Pain

Although acute chest pain accounts for five million emergency room visits annually, only 10% represent acute myocardial infarctions (AMI). Even patients with negative evaluations of chest symptoms experience subsequent cardiac events. Patients readmitted with AMI within 90 days after a cardiac evaluation were examined to identify potential errors in management that may have Led to readmission. Only six of 2,340 patients met criteria for AMI after a negative work-up. No medical errors were found to account for the subsequent AMI. No other previously published reports have investigated the quality of chest pain evaluations to find missed opportunities for cardiac event prevention.

Risk stratification and prognostic implication of plasma biomarkers in nondiabetic patients with stable coronary artery disease: the role of high-sensitivity C-reactive protein

STUDY OBJECTIVES

To evaluate the implication of plasma biomarkers to future cardiovascular events in nondiabetic patients with stable coronary artery disease (CAD). Designs and settings: Prospective, follow-up study at a tertiary referral center. Patients and measurement: Serial plasma biomarkers including high-sensitivity C-reactive protein (hsCRP), homocysteine, soluble adhesion molecules, von Willebrand factor, and lipid profiles were determined before coronary angiograms in a series of nondiabetic CAD patients with stable angina. Among them, 75 consecutive patients who received coronary revascularization (48 coronary interventions and 27 coronary bypass surgeries) later and another 75 age- and gender-matched patients who preferred medical treatment were both enrolled. In patients of each group, major cardiovascular events including cardiac death, nonfatal myocardial infarction, new or repeated coronary revascularization, and hospitalization for unstable angina, stroke, or peripheral artery disease were prospectively followed up for at least 6 months.

RESULTS

Patients were followed up to 40 months (median, 18 months). The incidences of major cardiovascular events were similar between the two groups. For patients with medical treatment, plasma levels of hsCRP, homocysteine, low-density lipoprotein, and the ratio of total cholesterol (TC) to high-density lipoprotein cholesterol (HDL-C) were significantly higher in those with cardiovascular events than those without. However, only hsCRP > 0.1 mg/dL (relative risk [RR], 2.78; 95% confidence interval [CI], 1.21 to 6.41; p = 0.016) and TC/HDL-C ratio > 4.8 (RR, 2.42; 95% CI, 1.04 to 5.65; p = 0.041) were independent predictors by multivariable analysis. For patients with revascularization, basal plasma hsCRP levels were higher in those with cardiovascular events than those without (p = 0.04). However, no biochemical markers could predict future major cardiovascular events in these patients.

CONCLUSIONS

In nondiabetic patients with CAD, basal plasma hsCRP levels were increased with future cardiovascular events regardless of different treatment strategies. Both plasma hsCRP level and TC/HDL-C ratio independently predict future cardiovascular events, confirming the role of plasma biomarkers in clinical risk stratification especially in patients with medical treatment.

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

Patients with symptoms suggestive of, but at low risk for, acute coronary syndrome (ACS), who have a negative electrocardiogram (EKG) and a single normal troponin I at 6-9 h after symptom onset are frequently discharged from our Emergency Department (ED). We sought to determine their rate of adverse cardiac events at 30 days (ACE-30), defined as cardiac death or myocardial infarction (MI), by chart review, telephone interview, or county death records. Of 663 patients, data were available for 588 (89%). Mean age was 48 years; 59% were male. There were 390 patients (66%) who complained of chest pain. Previous coronary artery disease (CAD) was reported in 145 patients (25%). Two patients (0.34%) had ACE-30, both with non-ST elevation MI. There were no cases of cardiac death. None of the patients died in Hennepin County within 30 days. At our institution, low-risk patients with symptoms suggestive of ACS who are discharged home after a normal cTnI drawn 6-9 h after symptom onset have a very low incidence of cardiac events at 30 days.

Prognostic value of predischarge dobutamine stress echocardiography in chest pain patients with a negative cardiac troponin T

OBJECTIVES

We prospectively studied the prognostic value of predischarge dobutamine stress echocardiography (DSE) in low-risk chest pain patients with a normal or nondiagnostic electrocardiogram (ECG) and a negative serial troponin T.

BACKGROUND

Noninvasive stress testing is recommended before discharge or within 72 h in patients with low-risk chest pain. The prognostic value of immediate DSE has not been studied in a blinded, prospective fashion.

METHODS

Patients presenting at the emergency room within 6 h of symptom onset and a normal or nondiagnostic ECG were eligible. Dobutamine stress echocardiography was performed after unstable coronary artery disease was ruled out by a standard rule-out protocol and a negative serial troponin T; the occurrence of any new wall motion abnormality was considered positive. Results were kept blinded. End points were cardiac death, myocardial infarction, rehospitalization for unstable angina or revascularization.

RESULTS

In total, 377 patients were included. There were 2 deaths, 2 myocardial infarctions, 8 rehospitalization for unstable angina, and 10 revascularizations at six-month follow-up. The end points occurred in 8/26 (30.8%) patients with a positive versus 14/351 (4.0%) patients with a negative DSE (odds ratio, 10.7; 95% confidence interval, 4.0 to 28.8; p < 0.0001). By multivariate analysis, DSE remained a predictor of end points (p < 0.0001).

CONCLUSIONS

A predischarge DSE had important, independent prognostic value in low-risk, troponin negative, chest pain patients.

[Chest pain units. Organization and protocol for the diagnosis of acute coronary syndromes]

The two main goals of chest pain units are the early, accurate diagnosis of acute coronary syndromes and the rapid, efficient recognition of low-risk patients who do not need hospital admission. Many clinical, practical, and economic reasons support the establishment of such units. Patients with chest pain account for a substantial proportion of emergency room turnover and their care is still far from optimal: 8% of patients sent home are later diagnosed of acute coronary syndrome and 60% of admissions for chest pain eventually prove to have been unnecessary.We present a systematic approach to create and manage a chest pain unit employing specialists headed by a cardiologist. The unit may be functional or located in a separate area of the emergency room. Initial triage is based on the clinical characteristics, the ECG and biomarkers of myocardial infarct. Risk stratification in the second phase selects patients to be admitted to the chest pain unit for 6-12 h. Finally, we propose treadmill testing before discharge to rule out the presence of acute myocardial ischemia or damage in patients with negative biomarkers and non-diagnostic serial ECGs.