Utility of stress echocardiography in the triage of patients with atypical chest pain from the emergency department

Major adverse cardiac events after emergency department evaluation of chest pain patients with advanced testing: Systematic review and meta-analysis

OBJECTIVES

Our primary objective was to describe the risk of major adverse cardiac events (MACE) at 1, 6, and 12 months after a negative coronary computed tomography angiogram (cCTA), electrocardiogram (ECG) stress test, stress echocardiography, and myocardial perfusion scintigraphy (MPS) in low- to intermediate-risk patients.

METHODS

Initially, 952 articles were identified for screening, 81 met criteria for full-text review, and once risk of bias was assessed, 33 articles were included in this meta-analysis. We utilized a random-effects model to assess pooled MACE event proportion for patients undergoing evaluation of acute coronary syndrome (ACS) when risk stratified to a low- to intermediate-risk category after undergoing standard testing. Heterogeneity analysis was performed using Cochrane's Q-test and I² statistic.

RESULTS

Twenty-one studies evaluated follow-up at 1 month with cCTA having a 0.09% (95% confidence interval [CI] = 0.03% to 0.26%) pooled MACE compared to 0.23% (95% CI = 0.01% to 5.8%) of the exercise stress testing (p = 1). MPS and cCTA had an overall event rate of 0.15% (95% CI = 0.06% to 0.41%) at 6 months (I²  = 0%). At 12 months, a subgroup analysis found a pooled cCTA MACE of 0.16% (95% CI = 0.04% to 0.65%) compared to 1.68% (95% CI = 0.01% to 2.6%) for stress echocardiography with low within-group heterogeneity (I²  = 0%). Subgroup analysis of cCTA with no disease versus nonobstructive disease (<50% stenosis) did not find statistical difference in the MACE at both 1 month (0.17% [95% CI = 0.04% to 0.67%] vs. 0.06% [95% CI = 0.01% to 0.34%]) and 12 months (0.44% [95% CI = 0.09% to 2.2% vs. 0.54% [95% CI = 0.19% to 1.5%]).

CONCLUSIONS

Patients presenting with chest pain who have a coronary CTA showing < 50% stenosis, negative ECG stress test, stress echocardiography, or stress myocardial perfusion scan in the past 12 months can be discharged without any further risk stratification if their ECG and troponin are reassuring given low MACE.

Prognostic value of real time dobutamine stress myocardial contrast echocardiography in patients with chest pain syndrome

The aims of this study were (1) to evaluate the prognostic value of negative wall motion (WM) and myocardial perfusion during contrast-dobutamine stress echocardiography (DSE), (2) to determine whether WM-myocardial contrast echocardiography (MCE) had incremental prognostic value over just WM during DSE in patients with chest pain in the emergency room (ER), and (3) to compare the prognostic value of negative DSE-WM, and DSE-WM-MCE to nuclear-myocardial perfusion imaging (N-MPI) in a similar patient population over the same time period. We retrospectively studied 569 patients with real time contrast DSE, and 147 patients underwent N-MPI for evaluation of chest pain. Follow-up for cardiac events was obtained between 12 and 25 months. The cumulative cardiac event-free survival was 94.5% in negative DSE-WM, 97.1% in negative DSE-WM-MCE and 96.7% in negative N-MPI group. Cardiac event-free survival of the negative DSE-WM-MCE group was significantly higher than the DSE-WM group (log rank P < 0.01), and similar in the DSE-WM-MCE group compared to the N-MPI group. Combined WM and perfusion during DSE was the strongest independent predictor for cardiac events. The negative predictive power of DSE-WM-MCE is superior to that of just negative DSE-WM and is comparable to that of N-MPI. Myocardial perfusion and WM analysis during DSE provide independent information for predicting cardiac events in patients with chest pain syndrome in the ER.

Predictive value of normal dobutamine stress echocardiogram in patients with low-risk acute chest pain

Dobutamine stress echocardiography (DSE) has been proposed as a tool for risk stratification of patients with acute chest pain (ACP). In this single-center study, we evaluated the negative predictive value of DSE in 178 patients who presented with low-risk ACP (normal or inconclusive electrocardiogram and negative markers of myocardial damage) and were discharged following a maximal DSE that did not reveal ischemia. During the follow-up (median 321 days), 2 of the 178 patients were admitted with an acute coronary syndrome and were diagnosed with obstructive coronary artery disease at angiography. In the time frame of the study, the negative predictive value of a normal and maximal DSE for an adverse cardiac event was 98.9% (95% CI: 96.0-99.8%). Thus, a normal DSE has a high negative predictive value and comprises a safe and effective tool for early risk stratification of patients who present with acute chest pain of low risk.

Effect on quality of life of different accelerated diagnostic protocols for management of patients presenting to the emergency department with acute chest pain

This study assessed the effects on quality of life (QoL) of dobutamine-atropine stress echocardiography (DASE) and electrocardiogram exercise testing (EET) accelerated diagnostic protocols for early stratification of low-risk patients with acute chest pain (ACP). A total of 290 patients with ACP, a nondiagnostic electrocardiogram, and negative biomarkers were randomly assigned to an accelerated diagnostic protocol (DASE, n = 110, or EET, n = 89) or usual care (n = 91) and followed up for 2 months. QoL was assessed at discharge and 2-month follow-up using the Nottingham Health Profile questionnaire. Baseline and 2-month follow-up answers to the Nottingham Health Profile questionnaire were available for 207 patients (71%; 55 in the usual-care, 77 in the DASE, and 75 in the ETT arm). At predischarge, patients in the usual-care arm reported higher impairment in the physical mobility and pain dimensions compared with the DASE and EET arms (p = 0.019 and p = 0.023, respectively). At 2-month follow-up, QoL improved in all groups; however, patients in the usual-care arm had significantly worse scores than patients managed using accelerated diagnostic protocols in the physical mobility, pain, social isolation, emotional reactions, and energy level dimensions (p = 0.014, p = 0.002, p = 0.04, p = 0.01, and p = 0.003, respectively). In conclusion, low-risk patients with ACP had non-negligible impairment of QoL in the acute phase. Emergency department ADPs with early DASE and EET reduced QoL impairment at both baseline and 2-month follow-up.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Comparison of early dobutamine stress echocardiography and exercise electrocardiographic testing for management of patients presenting to the emergency department with chest pain

This study compared the cost-effectiveness of dobutamine-atropine stress echocardiography (DASE) and electrocardiographic exercise testing (EET) implemented in emergency department accelerated diagnostic protocols for the early stratification of low-risk patients presenting with acute chest pain (ACP). One hundred ninety-nine patients with ACP, nondiagnostic electrocardiographic results, and negative biomarker results were randomized to DASE (n = 110) or EET (n = 89) <6 hours after emergency department presentation. Patients with negative risk assessment results were immediately discharged and followed for 2 months. Ninety patients (82%) in the DASE arm and 78 (88%) in the EET arm were discharged after the diagnosis of nonischemic ACP. The mean lengths of stay in the hospital were 23 +/- 12 and 31 +/- 23 hours in the DASE and EET arms, respectively (p = 0.01). No 2-month follow-up events occurred in DASE patients, and the event rate was significantly higher in EET patients (0% vs 11%, p = 0.004). The DASE strategy showed lower costs compared with the EET strategy at 1-month ($1,026 +/- $250 vs $1,329 +/- $1,288, p = 0.03) and 2-month ($1,029 +/- 253 vs $1,684 +/- $2,149, p = 0.005) follow-up. In conclusion, early DASE in emergency department triage of low-risk patients with ACP is safe and reduces costs of care compared to EET.

The Prognostic Value of Normal Exercise Myocardial Perfusion Imaging and Exercise Echocardiography

OBJECTIVES

The purpose of this work was to determine the prognostic value of normal exercise myocardial perfusion imaging (MPI) tests and exercise echocardiography tests, and to determine the prognostic value of these imaging modalities in women and men.

BACKGROUND

Exercise MPI and exercise echocardiography provide prognostic information that is useful in the risk stratification of patients with suspected coronary artery disease (CAD).

METHODS

We searched the PubMed, Cochrane, and DARE databases between January 1990 and May 2005, and reviewed bibliographies of articles obtained. We included prospective cohort studies of subjects who underwent exercise MPI or exercise echocardiography for known or suspected CAD, and provided data on primary outcomes of myocardial infarction (MI) and cardiac death with at least 3 months of follow-up. Secondary outcomes (unstable angina, revascularization procedures) were abstracted if provided. Studies performed exclusively in patients with CAD were excluded.

RESULTS

The negative predictive value (NPV) for MI and cardiac death was 98.8% (95% confidence interval [CI] 98.5 to 99.0) over 36 months of follow-up for MPI, and 98.4% (95% CI 97.9 to 98.9) over 33 months for echocardiography. The corresponding annualized event rates were 0.45% per year for MPI and 0.54% per year for echocardiography. In subgroup analyses, annualized event rates were <1% for each MPI isotope, and were similar for women and men. For secondary events, MPI and echocardiography had annualized event rates of 1.25% and 0.95%, respectively.

CONCLUSIONS

Both exercise MPI and exercise echocardiography have high NPVs for primary and secondary cardiac events. The prognostic utility of both modalities is similar for both men and women.

Stress echo in chest pain unit: the SPEED trial

BACKGROUND

Emergency room (ER) evaluation of patients with acute chest pain and non-diagnostic electrocardiography (ECG) remains a frequent and difficult problem.

AIM

To assess safety and prognostic implications of pharmacological stress echocardiography in the ER chest pain unit (CPU).

METHODS

A total of 552 patients (321 males, age 58+/-12.6 years) with acute chest pain, negative serial enzymes and/or troponin, and ECG recordings, and normal/unchanged resting left ventricular function were prospectively enrolled and underwent pharmacological (dipyridamole or dobutamine) stress echo. Six echo labs that had passed the preliminary quality control for stress echo reading entered the study. Follow-up was obtained in all patients after a median period of 13 months.

RESULTS

No significant adverse events were observed during the test. Stress echocardiography was negative in 502 patients (91%) and positive in 50 (9%). The 502 patients with negative stress echocardiography were discharged with no or unchanged anti-ischemic medications. While the 50 patients with positive stress echo were admitted to the coronary care unit, 44 of these underwent coronary angiography with the result that 42 out of 44 showed significant coronary artery disease. There were 45 events in the follow-up: six in the 502 patients with negative and 39 in the 50 patients with positive stress echo (1.2% vs. 78%, p<0.001). The negative predictive value of stress echocardiography was 98.8% for all events and 99.6% for hard events.

CONCLUSIONS

Stress echocardiography is a feasible, safe, and effective tool for early stratification of patients admitted to the ER with acute chest pain and non-ischemic ECG and resting echo.

Cardiac imaging in women: use of radionuclide myocardial perfusion imaging and echocardiography for acute chest pain

Evidence for the value of noninvasive cardiac imaging in patients for the detection of ischemic heart disease has traditionally come from trials using male patients. The application of such technology for women is often presumptive. Because there is an overall lower prevalence of ischemic heart disease in women, difference in body habitus, and smaller heart size, cardiac imaging in women presents unique challenges for imaging specialists and cardiologists. With the introduction of technetium-99 meters perfusion agents, gated single-photon emission computed tomography, and attenuation correction, myocardial perfusion imaging (MPI) in women has achieved a high sensitivity and specificity for the detection of coronary artery disease similar to that observed in men. With harmonic imaging and myocardial contrast agents, two-dimensional echocardiography offers comparable diagnostic accuracy in women. More importantly, MPI and stress echocardiography have prognostic value in predicting future cardiovascular events. The severity and extent of the single-photon emission computed tomography myocardial perfusion defects independently predict future cardiovascular events. Myocardial perfusion rest imaging during acute chest pain has a 99% negative predictive value of subsequent cardiovascular events, and a positive study MPI is the most important predictor for future cardiac events. Both MPI and stress echocardiography can direct high-risk patients to more invasive management or selectively identify lower-risk patients, allowing safe discharge from the emergency department and unnecessary hospitalization. Using a triage approach incorporating MPI or rest echocardiography in patients with acute chest pain results in significant cost savings. However, data on rest imaging in women during acute chest pain are still lacking.

The effect of real time 2-D-echocardiography on medical decision-making in the emergency department

2-D Echocardiography (ECHO) represents an important tool for the evaluation of the Emergency Department (ED) patient with suspected cardiovascular (CV) pathology. The present study assesses the degree of effect of real time ECHO on Emergency Physician diagnosis, treatment, and disposition of CV patients and their level of confidence in these decisions. One hundred ED patients with suspected CV pathology were enrolled into this prospective, interventional study. Senior level physicians were asked their level of confidence regarding patient diagnosis, treatment, and disposition decisions before and after the ECHO was done and interpreted by a certified sonographer in the ED. Physicians were then asked if ECHO changed any of these decisions. Patient age was 56.4 +/- 15.8 (range 27-93) years. Chest pain (n = 45) and shortness of breath (n = 38) were the most common presenting symptoms. Eighty-six of the patients were admitted. There was a change in diagnosis in 37 patients, a change in treatment in 25 patients, and a change in disposition in 11 patients. Physicians indicated there was a change in confidence level post-ECHO in approximately 50% of patients. A significant change was seen in both a more and a less confident direction. Physicians were 3 times more confident regarding diagnosis, 7 times more confident regarding treatment, and 3 times more confident regarding disposition decision-making. Real time ECHO appears to have a significant level of impact on physician level of confidence and medical decision-making concerning patients with suspected cardiovascular pathology in the ED.

Emergency department evaluation of chest pain using exercise stress echocardiography

OBJECTIVE

Patients with a low risk of coronary artery disease (CAD) presenting to the emergency department (ED) with chest pain pose a diagnostic dilemma because a small percentage will suffer an acute myocardial infarction (MI) and sudden death. The authors conducted this study to determine whether exercise stress echocardiography (ESE) could be used to further support the safe discharge of these low-risk patients.

METHODS

A convenience sample of patients > or =30 years of age without a prior cardiac history who presented to an academic community hospital with chest pain, normal initial creatine kinase, and electrocardiography without ischemic changes underwent ESE within 6 +/- 1.7 hours (mean +/- SD). Abnormal ESE was defined as regional wall motion abnormality at rest or after exercise. The ED disposition and three- and six-month follow-up for cardiac events were recorded. This was a prospective observational cohort study.

RESULTS

Of a total of 149 eligible patients, 145 completed the study. The mean age (+/-SD) was 47 +/- 9 years; 56% were male. No adverse events were noted during ESE. Seven patients (5%) had abnormal ESE (2 with rest wall motion abnormalities and 5 with exercise-induced wall motion abnormalities). Five of the seven underwent cardiac catheterization; three had CAD. All patients received telephone follow-up at three months and six months. Of the 138 patients with a normal ESE, all were free of cardiac events at three months. One patient had a non-Q-wave MI at six months (negative predictive value = 99.3%, 95% CI = 97.8% to 100%).

CONCLUSIONS

Exercise stress echocardiography can be used to evaluate low-risk chest pain patients in the ED. Patients with a normal ESE may be considered for discharge with minimal risk of sequelae.

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

In summary, this article focused on the use of stress testing to risk-stratify patients at the conclusion of their emergency evaluation for ACI. As discussed, those patients in the probably not ACI category require additional risk stratification prior to discharge. It should be kept in mind that patients in this category are heterogeneous, containing subgroups at both higher and lower risk of ACI and cardiac events. The patients with lower pretest probability for ACI may only need exercise testing in the ED. Patients with higher pretest probability should undergo myocardial perfusion or echocardiographic stress testing to maximize diagnostic and prognostic information. Prognostic information is the key to provocative testing in the ED. Prognostic information is the component that will help emergency physicians identify the patients who may be discharged home safely without having to worry about a 6% annual cardiac death rate and a 10% overall death rate over the next 30 months. Stress testing provides this key prognostic data, and it can be obtained in short-stay chest pain observation units in a safe, timely, and cost-effective fashion.

Provocative testing for chest pain

Since the first Chest Pain Center (CPC) was set up in 1981 to speed up the evaluation and treatment of patients with acute myocardial infarction, the original concept has been expanded to include rapid evaluation of chest pain patients with the appropriate streamlining of care and incorporation of the latest in technology. It has also been established that among patients presenting with acute chest pain, a very low-risk group with less than 5% probability of a coronary event can be identified. The recognition of this group could prevent unnecessary admissions, affording more appropriate patient care and improved cost-effectiveness. The efficient management of these chest pain patients requires that there be reductions in: (1) delays in therapy, (2) "soft" admissions, (3) inappropriate dispositions, and (4) cost. With time, provocative testing (PT) for chest pain patients has been brought forward to the frontline. PT methods are now being studied in hundreds of emergency department (ED) patients, followed up over several months to ascertain the predictive value of both positive and negative test results. More and more CPCs are now using PT as part of their management protocol, in terms of decision-making pertaining to prognostification, treatment and disposition. This could be in the form of the ECG graded exercise test (GXT), stress echocardiography (SE) and stress single-photon emission computed tomography (SPECT) radionuclide perfusion imaging. The GXT is fairly widely used currently, SE is gaining popularity and stress radionuclide perfusion imaging will perhaps gain more acceptance as the experience with its use as well as the number of randomized controlled studies increase. As we move into the new millennium, the emergency physicians must familiarize themselves with the latest in the state-of-the-art concepts and technology to render improved, up-to-date and more cost-effective patient care.

Role of echocardiography in acute chest pain syndrome

Fewer than one third of patients presenting to the emergency department with complaints of chest pain have an acute coronary syndrome. The electrocardiogram provides a specific diagnosis only in 40% of patients with acute myocardial infarction. The presence of regional wall-motion abnormalities at echocardiography in patients without known coronary artery disease is a moderate indicator of an increased likelihood of acute myocardial ischemia or myocardial infarction with a positive predictive accuracy of about 50%. More important, the absence of regional wall-motion abnormalities identifies a subset of patients unlikely to have a myocardial infarction with a negative predictive accuracy of about 95%. Echocardiography can provide incremental prognostic information to identify patients at risk of early or late cardiac events, even after consideration of clinical, historical, and electrocardiographic variables. The application of new contrast agents to echocardiography will probably allow an early and more accurate evaluation of patients with chest pain of uncertain significance.

Evaluation of chest pain suspicious for acute coronary syndrome: use of an accelerated diagnostic protocol in a chest pain evaluation unit

Management of patients presenting to the emergency department with chest pain suggestive of acute myocardial infarction (AMI) remains a continuing challenge. A low threshold for admission has been traditional because of concern for patient welfare and the litigation potential associated with the inadvertent discharge of patients with ischemic events. Because of this approach, < 30% of patients admitted for chest pain ultimately are found to have an acute coronary syndrome. To reduce unnecessary admissions, maintain patient safety, and enhance cost-effectiveness, innovative strategies have been applied to the management of patients with chest pain. It is now recognized that a low-risk group can be identified by the clinical presentation and initial electrocardiogram. Chest-pain centers have been developed to provide further risk stratification and systematic management of these patients. We employ an accelerated diagnostic protocol based on immediate exercise treadmill testing to evaluate low-risk patients. Moderate-risk patients are assessed over a 6-hour observation period with serial electrocardiograms and evaluation of cardiac-injury markers. Patients with positive evaluations are admitted. Those with negative results undergo either exercise echocardiography or rest myocardial perfusion imaging utilizing technetium-99m sestamibi. Patients with positive functional tests are admitted. Those with negative studies are discharged with outpatient follow-up. These strategies have provided a safe and accurate means of patient disposition from the emergency department with the potential for vital cost savings.

Chest pain emergency units

Each year in the United States, more than 2 million patients are hospitalized with chest pain suggestive of myocardial ischemia, with fewer than 20% of these patients having an acute coronary event. Chest pain emergency units have been created to facilitate urgent therapy for patients with a serious cardiovascular event and to triage lower risk patients to less intensive, more cost-effective inpatient care or discharge to home. The clinical history, physical examination, and initial electrocardiogram are key to initial stratification of patients for further management, but additional methods are necessary to clearly distinguish patients with inconclusive findings at presentation as high- and low-risk. Innovative electrocardiographic methods have increased sensitivity for detecting myocardial ischemia. Accelerated diagnostic protocols with new cardiac serum markers can detect myocardial ischemia or infarction with increasing accuracy. Early echocardiographic, scintigraphic, and treadmill stress protocols can further evaluate patients who have nondiagnostic electrocardiograms and negative serum markers. This review presents the current status of chest pain emergency units and the evolving management strategies they encompass.