Stress testing for risk stratification of patients with low to moderate probability of acute cardiac ischemia

Provocative biomarker stress test: stress-delta N-terminal pro-B type natriuretic peptide

Objective

Stress testing is commonly performed in emergency department (ED) patients with suspected acute coronary syndrome (ACS). We hypothesised that changes in N-terminal pro-B type natriuretic peptide (NT-proBNP) concentrations from baseline to post-stress testing (stress-delta values) differentiate patients with ischaemic stress tests from controls.

Methods

We prospectively enrolled 320 adult patients with suspected ACS in an ED-based observation unit who were undergoing exercise stress echocardiography. We measured plasma NT-proBNP concentrations at baseline and at 2 and 4  hours post-stress and compared stress-delta NT-proBNP between patients with abnormal stress tests versus controls using non-parametric statistics (Wilcoxon test) due to skew. We calculated the diagnostic test characteristics of stress-delta NT-proBNP for myocardial ischaemia on imaging.

Results

Among 320 participants, the median age was 51 (IQR 44-59) years, 147 (45.9%) were men, and 122 (38.1%) were African-American. Twenty-six (8.1%) had myocardial ischaemia. Static and stress-deltas NT-proBNP differed at all time points between groups. The median stress-deltas at 2  hours were 10.4 (IQR 6.0-51.7) ng/L vs 1.7 (IQR -0.4 to 8.7) ng/L, and at 4  hours were 14.8 (IQR 5.0-22.3) ng/L vs 1.0 (-2.0 to 10.3) ng/L for patients with ischaemia versus those without. Areas under the receiver operating curves were 0.716 and 0.719 for 2-hour and 4-hour stress-deltas, respectively. After adjusting for baseline NT-proBNP levels, the 4-hour stress-delta NT-proBNP remained significantly different between the groups (p=0.009).

Conclusion

Among patients with ischaemic stress tests, static and 4-hour stress-delta NT-proBNP values were significantly higher. Further study is needed to determine if stress-delta NT-proBNP is a useful adjunct to stress testing.

Implementation of a Risk Stratification and Management Pathway for Acute Chest Pain in the Emergency Department

OBJECTIVES

Chest pain is a common complaint in the emergency department, and a small but important minority represents an acute coronary syndrome (ACS). Variation in diagnostic workup, risk stratification, and management may result in underuse, misuse, and/or overuse of resources.

METHODS

From July to October 2014, we conducted a prospective cohort study in an academic medical center by implementing a Standardized Clinical Assessment and Management Plan (SCAMP) for chest pain based on the HEART score. In addition to capturing adherence to the SCAMP algorithm and reasons for any deviations, we measured troponin sample timing; rates of stress test utilization; length of stay (LOS); and 30-day rates of revascularization, ACS, and death.

RESULTS

We identified 239 patients during the enrollment period who were eligible to enter the SCAMP, of whom 97 patients were entered into the pathway. Patients were risk stratified into one of 3 risk tiers: high (n = 3), intermediate (n = 40), and low (n = 54). Among low-risk patients, recommendations for troponin testing were not followed in 56%, and 11% received stress tests contrary to the SCAMP recommendation. None of the low-risk patients had elevated troponin measurements, and none had an abnormal stress test. Mean LOS in low-risk patients managed with discordant plans was 22:26 h/min, compared with 9:13 h/min in concordant patients (P < 0.001). Mean LOS in intermediate-risk patients with stress testing was 25:53 h/min, compared with 7:55 h/min for those without (P < 0.001). At 30 days, 10% of intermediate-risk patients and 0% of low-risk patients experienced an ACS event (risk difference 10% [0.7%-19%]); none experienced revascularization or death. The most frequently cited reason for deviation from the SCAMP was lack of confidence in the tool.

CONCLUSIONS

Compliance with SCAMP recommendations for low- and intermediate-risk patients was poor, largely due to lack of confidence in the tool. However, in our study population, outcomes suggest that deviation from the SCAMP yielded no additional clinical benefit while significantly prolonging emergency department LOS.

Death or revascularization among nonadmitted ED patients with low-positive vs negative troponin T results

STUDY OBJECTIVE

Compare outcomes among emergency department (ED) patients with low-positive (0.01-0.02 ng/mL) vs negative troponin T.

METHODS

Retrospective cohort study of nonadmitted ED patients with troponin testing at a tertiary-care hospital. Trained research assistants used a structured tool to review charts from all nonadmitted ED patients with troponin testing, 12/1/2009 to 11/30/2010. Outcomes of death and coronary revascularization were assessed at 30 days and 6 months via medical record review, Social Security Death Index searches, and patient contact.

RESULTS

There were 57596 ED visits; with 33388 (58%) discharged immediately, 6410 (11%) assigned to the observation unit, and 17798 (31%) admitted or other. Troponin was measured in 2684 (6.7%) of the nonadmitted cases. Troponin was negative in 2523 (94.0%), low positive in 78 (2.9%), and positive (≥0.03 ng/mL) in 83 (3.1%). Of troponin-negative cases, 0.8% (95% CI, 0.4-1.1%) died or were revascularized by 30 days, vs 2.8% (95% CI, 0.0-6.7%) of low-positive cases (risk difference [RD], 2.0%; 95% CI, -1.8 to 5.9%). At 6 months, the rates were 1.7% (95% CI, 1.1-2.2%) and 12.9% (95% CI, 5.0-20.7%) (RD, 11%; 95% CI, 3.3-19.1%). Death alone at 30 days occurred in 0.4% (95% CI, 0.1-0.6%) vs 1.3% (95% CI, 0.0-3.8%) (RD, 0.9%; 95% CI, -1.6 to 3.4%). Death at 6 months occurred in 1.2% (95% CI, 0.8-1.6%) vs 11.7% (95% CI, 4.5-18.9%) (RD, 10%; 95% CI, 3.3-17.7%).

CONCLUSION

Among patients not initially admitted, rates of death and coronary revascularization differed insignificantly at 30 days but significantly at 6 months. Detailed inspection of our results reveals that the bulk of the added risk at 6 months was due to non-cardiac mortality.

Evolving practice of hospital medicine and its impact on hospital throughput and efficiencies

Hospitalists are uniquely positioned to implement strategies to improve patient flow and efficiency. Hospital leaders have stated they expect hospitalists to comanage surgical patients, participate in observation units, and screen medical admissions, in addition to providing inpatient care for medical patients. We review how the hospitalists' role in acute inpatient care, surgical comanagement, short stay units, chest pain units, and active bed management has improved throughput and patient flow.

The feasibility of Rubidium-82 positron emission tomography stress testing in low-risk chest pain protocol patients

OBJECTIVE

To evaluate the feasibility of dipyridamole-induced reversible ischemia on myocardial perfusion positron emission tomography (PET) imaging using Rubidium-82 (Rb-82 PET) to predict the presence of acute coronary syndrome (ACS) in emergency department (ED) chest pain patients at low risk who were admitted to an observation unit.

METHODS

Retrospective cross-sectional study of electronic medical records after computerized record retrieval. We matched all ED chest pain visits to a database of all scans read by cardiology between January 1, 2004 and January 1, 2006. A PET scan was performed at the ED physician's discretion after a negative observation unit workup, including serial cardiac biomarkers and ECGs. Data were collected on a standardized abstraction instrument.

RESULTS

There were 7,691 ED visits for chest pain. Among these patients, 1177 had an Rb-82 PET. Fifty four (4.6%) of these patients had an abnormal or probably abnormal scan. Of these, 28 had catheter-proven significant coronary disease, requiring either revascularization or intensive medical management; 22 patients had ACS by clinical assessment but did not undergo catheterization. Four had no coronary artery disease on catheterization.

CONCLUSION

In a low-risk chest pain population, cardiac PET imaging had true-positive cardiac catheterization rates which were comparable to prior studies of SPECT sestimibi imaging and coronary CTA imaging. With the rapid dissemination of PET technology, and superior performance compared to current imaging methods, myocardial perfusion PET is a feasible alternative to traditional provocative testing in an ED observation unit.

Pain catastrophizing in patients with noncardiac chest pain: relationships with pain, anxiety, and disability

OBJECTIVE

To examine the contributions of chest pain, anxiety, and pain catastrophizing to disability in 97 patients with noncardiac chest pain (NCCP) and to test whether chest pain and anxiety were related indirectly to greater disability via pain catastrophizing.

METHODS

Participants completed daily diaries measuring chest pain for 7 days before completing measures of pain catastrophizing, trait anxiety, and disability. Linear path model analyses examined the contributions of chest pain, trait anxiety, and catastrophizing to physical disability, psychosocial disability, and disability in work, home, and recreational activities.

RESULTS

Path models accounted for a significant amount of the variability in disability scales (R(2) = 0.35 to 0.52). Chest pain and anxiety accounted for 46% of the variance in pain catastrophizing. Both chest pain (beta = 0.18, Sobel test Z = 2.58, p < .01) and trait anxiety (beta = 0.14, Sobel test Z = 2.11, p < .05) demonstrated significant indirect relationships with physical disability via pain catastrophizing. Chest pain demonstrated a significant indirect relationship with psychosocial disability via pain catastrophizing (beta = 0.12, Sobel test Z = 1.96, p = .05). After controlling for the effects of chest pain and anxiety, pain catastrophizing was no longer related to disability in work, home, and recreational activities.

CONCLUSIONS

Chest pain and anxiety were directly related to greater disability and indirectly related to physical and psychosocial disability via pain catastrophizing. Efforts to improve functioning in patients with NCCP should consider addressing pain catastrophizing.

Emergency physician high pretest probability for acute coronary syndrome correlates with adverse cardiovascular outcomes

OBJECTIVES

The value of unstructured physician estimate of risk for disease processes, other than acute coronary syndrome (ACS), has been demonstrated. The authors sought to evaluate the predictive value of unstructured physician estimate of risk for ACS in emergency department (ED) patients without obvious initial evidence of a cardiac event.

METHODS

This was a post hoc secondary analysis of the Internet Tracking Registry for Acute Coronary Syndromes (i*trACS), a prospectively collected multicenter data registry of patients over the age of 18 years presenting to the ED with symptoms of ACS between 1999 and 2001. In this registry, following patient history, physical exam, and electrocardiogram (ECG), the unstructured treating physician estimate of risk was recorded. A 30-day follow-up and a medical record review were used to determine rates of adverse cardiac events, death, myocardial infarction (MI), or revascularization procedure. The analysis included all patients with nondiagnostic ECG changes, normal initial biomarkers, and a non-MI initial impression from the registry and excluded those without complete data or who were lost to follow-up. Data were stratified by unstructured physician risk estimate: noncardiac, low risk, high risk, or unstable angina.

RESULTS

Of 15,608 unique patients in the registry, 10,145 met inclusion/exclusion criteria. Patients were defined as having unstable angina in 6.0% of cases; high risk, 23.5% of cases; low risk, 44.2%; and noncardiac, 26.3% of cases. Adverse cardiac event rates had an inverse relationship, decreasing from 22.0% (95% confidence interval [CI] = 18.8% to 25.6%) for unstable angina, 10.2% (95% CI = 9.0% to 11.5%) for those stratified as high risk, 2.2% (95% CI = 1.8% to 2.6%) for low risk, and to 1.8% (95% CI = 1.4% to 2.4%) for noncardiac. The relative risk (RR) of an adverse cardiac event for those with an initial label of unstable angina compared to those with a low-risk designation was 10.2 (95% CI = 8.0 to 13.0). The RR of an event for those with a high-risk initial impression compared to those with a low-risk initial impression was 4.7 (95% CI = 3.8 to 5.9). The risk of an event among those with a low-risk initial impression was the same as for those with a noncardiac initial impression (RR = 0.83, 95% CI = 0.6 to 1.2).

CONCLUSIONS

In ED patients without obvious initial evidence of a cardiac event, unstructured emergency physician (EP) estimate of risk correlates with adverse cardiac outcomes.

Development and Implementation of An Emergency Department Observation Unit Protocol for Deliberate Drug Ingestion in Adults – Preliminary Results

BACKGROUND

Patients presenting after reported overdose are typically precluded from admission to emergency department observation units (EDOU). The purpose of this study was to describe the initial experience with an EDOU overdose protocol.

METHODS

Retrospective chart review of all individuals presenting to a tertiary care hospital with a chief complaint of overdose or intoxication for the period 7/1/2004 through 12/24/2004. Inclusion criteria for EDOU placement included asymptomatic patients aged >or= 15 years presenting after known or suspected potentially toxic exposure. Exclusion criteria included isolated ethanol intoxication, presence of persistent self-injurious or violent behaviors, chronic intoxication, ingestion of sustained release preparation, and presence of previously defined high-risk criteria.

RESULTS

Retrospective chart review demonstrated that 163 patients presented to the ED after ingestion during this time period, of which 15 were excluded secondary to age. Six patients were admitted to the EDOU. No patient eloped or attempted further self-harm while in the EDOU. No clinical decompensation occurred. Another 27 patients were retrospectively identified as EDOU candidates, eight of whom were admitted to the MICU.

CONCLUSION

Although initial numbers are too small for meaningful analysis, the results suggest that prolonged observation of this problematic patient subset within an EDOU is feasible.

Can we identify those at risk for a nondiagnostic treadmill test in a chest pain observation unit?

BACKGROUND

Exercise treadmill testing (ETT) is a testing modality that has shown to be a useful chest pain observation unit (CPU). One limitation of this tool is the high rate of nondiagnostic tests. We aim to create a predictive model to discriminate a patient's risk for a nondiagnostic test.

METHODS

This is a retrospective analysis of consecutive subjects admitted to our CPU and undergoing an ETT from January 2001 to December 2006. To account for any variation in physician practice, the training set was those patients admitted January 2004 to December 2006 and the testing set comprised those evaluated January 2001 to December 2003. Recursive partitioning with 10-fold cross validation was used to identify significant variables associated with the outcome measure of a nondiagnostic treadmill test. The beta coefficient from the regression model was used to create a risk score. This risk score was then used stratify patients.

RESULTS

A total of 1708 subjects underwent ETT during the study period. The training set comprised 408 subjects with 62 having a nondiagnostic test. Logistic regression identified age, prior history of coronary artery disease, smoking, and diabetes variables used to create a scoring system. The testing set identified 387 (29.7) subjects meeting our criteria as low risk (9.0%) nondiagnostic test and identified 298 (22.9%) at high risk for a nondiagnostic test (32.8%).

CONCLUSION

Using a simple scoring system to stratify patients undergoing ETT into 3 risk groups, we were able to identify a low-risk group <10% and a high-risk group >30% for having a nondiagnostic ETT.

New methods for improved evaluation of patients with suspected acute coronary syndrome in the emergency department

This paper aims to identify and review new and unproven emergency department (ED) methods for improved evaluation in cases of suspected acute coronary syndrome (ACS). Systematic news coverage through PubMed from 2000 to 2006 identified papers on new methods for ED assessment of patients with suspected ACS. Articles found described decision support models, new ECG methods, new biomarkers and point-of-care testing, cardiac imaging, immediate exercise tests and the chest pain unit concept. None of these new methods is likely to be the perfect solution, and the best strategy today is therefore a combination of modern methods, where the optimal protocol depends on local resources and expertise. With a suitable combination of new methods, it is likely that more patients can be managed as outpatients, that length of stay can be shortened for those admitted, and that some patients with ACS can get earlier treatment.

How to improve the management of chest pain: hospitalists and use of prediction rules

BACKGROUND

Three percent of patients with acute myocardial infarction are still missed despite the excess number of admissions with chest pain. The purpose of this study was to review the characteristics of patients who were admitted with chest pain, to evaluate the appropriateness of admissions and the outcomes. We also discuss whether use of a prediction rule could have made a difference in the management of these cases.

METHODS

We performed retrospective chart review on all patients admitted to the hospitalist service with a diagnosis of chest pain. Each patient was risk stratified using Diamond and Forrester algorithm for probability of coronary artery disease (CAD), retrospectively. Results were analyzed using chi2 test or exact test and Student's t test.

RESULTS

Of 260 patients admitted with chest pain to the hospitalist service, only 24 (9.2%) received the final diagnosis of acute coronary syndrome (ACS). The patients in the ACS group were older and more likely to be male and to have a history of hyperlipidemia, CAD, peripheral vascular disease, cerebrovascular disease and percutaneous coronary intervention (PCI). Of 34 patients who underwent cardiac catheterization, 20 (58.8%) had occlusive CAD and 14 of them received PCI. Risk stratification of patients, retrospectively, revealed 28.3% of the total patient population was high risk, while 6.6% of them were low risk. The number of ACS cases was highest in the high risk group, while none was detected in the low risk group.

CONCLUSIONS

Our study demonstrated that using a prediction rule could have prevented about 6% of the chest pain admissions. Therefore, the use of risk stratification methods should be encouraged to decrease cost and improve efficiency of care.

Pain characteristics in patients with unexplained chest pain and patients with ischemic heart disease

BACKGROUND

Little scientific attention has been paid to providing a comprehensive multidimensional description of chest pain in patients with unexplained chest pain.

AIMS

The aims of the present study were: (1) to describe the symptom chest pain, including the dimensions of intensity, quality, duration and location in patients with unexplained chest pain (UCP); and (2) to identify similarities and differences in how patients with UCP and patients with ischemic heart disease (IHD) describe chest pain.

METHOD

A descriptive, correlational and comparative design. Totally 208 consecutive UCP patients and 40 IHD patients below 70 years of age participated. Pain was assessed using the instrument Pain-O-Meter.

RESULTS

The occurrence of chest pain was 79% (n=165) in UCP patients versus 60% (n=22) in the IHD patients (p=0.001). Patients with UCP reported greater pain intensity and used more sensory and affective words than IHD patients (p<0.01). Relationships between pain location and amount of body surface involved in the pain and pain intensity in both groups were found (p<0.001).

CONCLUSIONS

Our results showed some defining characteristics of the UCP group, but the many similarities between the two groups in their experience of chest pain made it impossible to clearly differentiate the groups' pain profiles.

A simple statistical model for prediction of acute coronary syndrome in chest pain patients in the emergency department

BACKGROUND

Several models for prediction of acute coronary syndrome (ACS) among chest pain patients in the emergency department (ED) have been presented, but many models predict only the likelihood of acute myocardial infarction, or include a large number of variables, which make them less than optimal for implementation at a busy ED. We report here a simple statistical model for ACS prediction that could be used in routine care at a busy ED.

METHODS

Multivariable analysis and logistic regression were used on data from 634 ED visits for chest pain. Only data immediately available at patient presentation were used. To make ACS prediction stable and the model useful for personnel inexperienced in electrocardiogram (ECG) reading, simple ECG data suitable for computerized reading were included.

RESULTS

Besides ECG, eight variables were found to be important for ACS prediction, and included in the model: age, chest discomfort at presentation, symptom duration and previous hypertension, angina pectoris, AMI, congestive heart failure or PCI/CABG. At an ACS prevalence of 21% and a set sensitivity of 95%, the negative predictive value of the model was 96%.

CONCLUSION

The present prediction model, combined with the clinical judgment of ED personnel, could be useful for the early discharge of chest pain patients in populations with a low prevalence of ACS.

A critical pathway for patients with acute chest pain and low risk for short-term adverse cardiac events: role of outpatient stress testing

STUDY OBJECTIVE

We evaluate the safety and feasibility of a critical care pathway protocol in which patients with acute chest pain who are low risk for coronary artery disease and short-term adverse cardiac outcomes receive outpatient stress testing within 72 hours of an emergency department (ED) visit.

METHODS

We performed an observational study of an ED-based chest pain critical pathway in an urban, community hospital in 979 consecutive patients. Patients enrolled in the protocol were observed in the ED before receiving 72-hour outpatient stress testing. The pathway was primarily analyzed for rates of death or myocardial infarction in the 6 months after ED discharge and outpatient stress testing. Secondary outcome measures included need for coronary intervention at initial stress testing and within 6 months after discharge, subsequent ED visits for chest pain, and subsequent hospitalization.

RESULTS

Of 871 stress-tested patients aged 40 years or older, who had low risk for coronary artery disease and short-term adverse cardiac events, and had 6-month follow-up, 18 (2%) required coronary intervention, 1 (0.1%) had a myocardial infarction within 1 month, 2 (0.2%) had a myocardial infarction within 6 months, 6 (0.7%) had normal stress test results after discharge but required cardiac catheterization within 6 months, and 5 (0.6%) returned to the ED within 6 months for ongoing chest pain. Hospital admission rates decreased significantly from 31.2% to 26.1% after initiation of the protocol (P<.001).

CONCLUSION

For patients with chest pain and low risk for short-term cardiac events, outpatient stress testing is feasible, safe, and associated with decreased hospital admission rates. With an evidence-based protocol, physicians efficiently identify patients at low risk for clinically significant coronary artery disease and short-term adverse cardiac outcomes.

Psychological treatments for noncardiac chest pain: recommendations for a new approach

OBJECTIVE

Our objective is to describe the current state of treatment for NCCP, identify barriers to treatment and limitations of current approaches, and to recommend treatment strategies, which may address these challenges.

METHODS

We describe the underlying rationale for treating NCCP and review the current literature concerning NCCP treatments and other brief approaches to outpatient treatment for psychosomatic illness.

RESULTS

Most treatments for NCCP have been based on the Attribution Model. Although effective, these treatments are appropriate and acceptable to only a small minority of NCCP patients. The Biopsychosocial Model has been used to treat psychosomatic conditions in outpatient groups and may overcome or avoid many of the limitations inherent in current treatment strategies for NCCP.

CONCLUSIONS

We recommend an intervention for NCCP that is brief, would be delivered in the emergency department setting (to take advantage of the Teachable Moment), and which is based on the Biopsychosocial Model.

Patients with suspected acute coronary syndrome in a university hospital emergency department: an observational study

BACKGROUND: Improved diagnostics in suspected acute coronary syndrome (ACS) are considered to be needed. To help clarify the current situation and the improvement potential, judged risk in the emergency department (ED) and outcome were analyzed among patients with suspected ACS at a university hospital. METHODS: 157 consecutive patients with symptoms of ACS were included at the ED during 10 days. Risk of ACS was estimated in the ED for each patient based on history, physical examination and ECG by assigning them to one of four risk categories; I (obvious myocardial infarction, MI), II (strong suspicion of ACS), III (vague suspicion of ACS), and IV (no suspicion of ACS). RESULTS: 4, 17, 29 and 50% of the patients were allocated to risk categories I-IV respectively. 74 patients (47%) were hospitalized but only 19 (26%) had ACS as the discharge diagnose. In risk categories I-IV, ACS rates were 100, 37, 12 and 0%, respectively. Of those admitted without ACS, at least 37% could probably, given perfect ED diagnostics, have been immediately discharged. 83 patients were discharged from the ED, and among them there were no hospitalizations for ACS or cardiac mortality at 6 months. Only about three patients per 24 h were considered eligible for a potential ED chest pain unit. CONCLUSIONS: Almost 75% of the patients hospitalized with suspected ACS did not have it, and some 40% of these patients could probably, given perfect immediate diagnostics, have been managed as outpatients. The potential for diagnostic improvement in the ED seems large.