ﺑﺎﺯﮔﺸﺖ ﺑﻪ ﺻﻔﺤﻪ ﻗﺒﻠﯽ
خرید پکیج
تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
نسخه الکترونیک
medimedia.ir

Noninvasive imaging for diagnosis in patients at low to intermediate risk for acute coronary syndrome

Noninvasive imaging for diagnosis in patients at low to intermediate risk for acute coronary syndrome
Literature review current through: May 2024.
This topic last updated: May 29, 2024.

INTRODUCTION — Many patients who are evaluated for acute chest pain are felt to be at low to intermediate pretest risk of an acute coronary syndrome (ACS) if they have resolution of symptoms, normal or nonischemic/nondiagnostic electrocardiograms (ECGs), and initial troponin value(s) that are not diagnostic for myocardial infarction (MI). Ultimately, these individuals may have unstable angina, nonischemic cardiac pain, or noncardiac pain. Evaluation of these patients generally occurs in a hospital emergency department or observation unit.

If myocardial ischemia is a concern, noninvasive cardiovascular testing can be used to assess for obstructive coronary artery disease (CAD) [1]. The use of noninvasive cardiovascular testing generally helps determine further management decisions, such as discharge, the need for invasive coronary angiography, or evaluation for other causes of symptoms. (See "Initial evaluation and management of suspected acute coronary syndrome (myocardial infarction, unstable angina) in the emergency department", section on 'Impact of missed diagnosis'.)

The use of noninvasive cardiovascular testing to assess the likelihood of an ACS is discussed here. The initial evaluation of patients with chest pain at low to intermediate risk for ACS, including determination of whether noninvasive imaging during rest and/or provocative stress testing is indicated, is discussed separately.

PATIENTS WITH ONGOING SYMPTOMS — For most patients with suspected MI and ongoing symptoms, diagnostic coronary angiography is appropriate. (See "Non-ST-elevation acute coronary syndromes: Selecting an approach to revascularization", section on 'Signs of ongoing myocardial dysfunction or infarction'.)

For hemodynamically stable patients with ongoing chest pain, a nonischemic ECG, and troponin values that are not elevated, unstable angina (or an unusual presentation of stable angina) remains a diagnostic possibility. (See "Diagnosis of acute myocardial infarction" and "Diagnosis of acute myocardial infarction", section on 'Definitions'.)

Rest (no stress) cardiac imaging may be useful. However, rest imaging has not been widely adopted. If rest imaging is to be performed, the choice of test depends on local expertise and availability.

The rationale for rest imaging derives from the pathophysiologic events that follow the onset of myocardial ischemia [2]:

When myocardial oxygen demand exceeds supply (due to either increased oxygen demand or reduced supply), the first abnormality detected is regional myocardial blood flow heterogeneity between the vascular beds supplied by normal and stenosed coronary arteries. This manifests as a regional perfusion defect on myocardial perfusion imaging.

Regional systolic dysfunction (manifest as regional wall motion abnormalities [RWMA]) is highly specific for regional ischemia in patients without prior abnormality. Regional systolic dysfunction may be seen on two-dimensional (2D) echocardiography.

Since regional flow heterogeneity and systolic dysfunction precede chest pain in the ischemic cascade, the absence of these phenomena (ie, a normal rest study) in a patient with ongoing chest pain is reliable evidence of the nonischemic nature of the chest pain. Noninvasive imaging studies have demonstrated that regional flow heterogeneity has a higher sensitivity for ACS while regional systolic dysfunction has a higher specificity. It should be kept in mind that an ACS may be present despite a noninvasive study with no RWMA and that a noninvasive study with RWMA may represent old MI.

Rest imaging for patients with suspected ACS in the emergency department (ED) is among the most rigorously studied areas in terms of evidence for the use of imaging, with numerous randomized controlled trials involving many of the modalities. Large trials have been performed using radionuclide myocardial perfusion imaging (rMPI) and substantial observational data exist for 2D echocardiography, which can also offer insights about nonischemic causes of chest pain [3,4]. Cardiovascular magnetic resonance (CMR) imaging requires provocative stress testing, and placing the patient with active chest pain in the scanner for a prolonged period of time is not appropriate.

The utility of testing varies across these tests in relation to whether symptoms are ongoing or have resolved. The longer the interval between the end of symptoms and the test, the lower the sensitivity of the test [5,6]. Assessment of RWMA appears to require ongoing symptoms for optimal sensitivity (unless MI has occurred). Perfusion or anatomic changes may persist for several hours or more despite resolution of symptoms. In general, we do not evaluate the patient with these rest studies if the patient has been pain free for more than two to three hours, but instead wait for final troponin results and plan for stress testing.

Radionuclide myocardial perfusion imaging — Multiple studies have validated the benefit from the use of acute rest single photon emission computed tomography (SPECT) rMPI in the evaluation of patients with chest pain and a nondiagnostic ECG. During rest rMPI with technetium (Tc)-99m sestamibi or Tc-99m tetrofosmin, the radiolabeled tracers accumulate in the myocardium proportionally to myocardial blood flow [7-12]. If these agents are injected during or shortly after resolution of chest pain, areas of ischemic myocardium demonstrate reduced radioactive counts (tracer uptake) (image 1). Because there is minimal redistribution of these agents over three to four hours, imaging can provide accurate information about myocardial perfusion at the time of injection even if the scintigraphy is delayed for a few hours after the injection. (See "Basic properties of myocardial perfusion agents".)

It must be emphasized that the lowest event rates are associated with scans that are completely normal. Equivocal scans are associated with event rates that are intermediate between those associated with normal and clearly abnormal scans (table 1). Thus, the interpretation of rMPI in ED patients should be geared towards obtaining maximum sensitivity and negative predictive value for potential disease by identifying and reporting any abnormality as significant.

Multiple studies have shown that patients with chest pain and normal images on acute rest rMPI can be safely discharged from the ED:

The efficacy of this approach was evaluated in a randomized controlled trial in which 2475 patients with suggestive chest pain within the previous three hours, a nondiagnostic ECG, and no prior MI were studied [12]. The patients were randomly assigned to resting Tc-99m SPECT or to routine ED assessment. An ACS was subsequently confirmed in 329 patients (13 percent). Patients with negative serial enzymes, no evolutionary changes on serial ECGs, and a negative follow-up stress test were considered to have noncardiac chest pain. There was no difference in the appropriate admission rate between the SPECT group and the controls (97 versus 96 percent for acute MI and 83 versus 81 percent for unstable angina). However, among patients confirmed to have noncardiac chest pain, the erroneous admission rate was significantly lower for the SPECT group (42 versus 52 percent).

The value of acute rest rMPI was evaluated in 532 consecutive patients presenting to an ED with a nondiagnostic ECG and a low to intermediate probability of an ACS [9]. A positive rMPI was present in 32 percent and was the only multivariable predictor of MI and was the most important independent predictor of MI or revascularization (figure 1). The sensitivity of a positive scan for MI and for MI or revascularization was 93 and 81 percent, respectively; the negative predictive value was 99 and 95 percent, respectively.

The value of rest imaging in identifying patients with ischemia was confirmed in a multicenter prospective trial in which Tc-99m tetrofosmin SPECT rMPI was performed in 357 patients who were admitted from the ED with symptoms suggestive of myocardial ischemia but with a normal or nondiagnostic ECG [10]. Among 20 patients who subsequently had an acute MI, 18 had an abnormal scan (sensitivity 90 percent); the specificity was 60 percent. The reduced specificity was in part due to patients with positive scans who had CAD but no acute MI. Because so few patients had an MI, the positive predictive value was only 12 percent; however, the negative predictive value was 99 percent (figure 2).

Two-dimensional echocardiography — Two-dimensional echocardiography is an accurate, noninvasive test that is able to detect evidence of myocardial ischemia or MI in patients with ongoing chest pain. Severe ischemia produces RWMA that can be visualized echocardiographically within seconds of coronary artery occlusion (12±5 and 19±8 seconds in two series of patients evaluated during transient coronary occlusions induced by angioplasty) [13,14]. These changes occur prior to the onset of ECG changes or the development of symptoms (figure 3) [15]. The RWMA reflects a localized decrease in the amplitude and rate of myocardial excursion, as well as a blunted degree of myocardial thickening and local remodeling.

Since ischemic RWMA develop prior to symptoms, chest pain in the absence of RWMA is likely not to be due to active myocardial ischemia. However, the converse is not true; the presence of RWMA does not establish the diagnosis of ischemia. There are a number of other causes of resting RWMA, including a prior MI, focal myocarditis, prior surgery, and cardiomyopathy.

Thus, echocardiography for an ACS has a high sensitivity but a relatively lower specificity. These predictions were confirmed in a study of 180 patients with chest pain in the ED. The following findings were noted [16]:

RWMA were present in 27 of 29 patients with an acute MI (sensitivity 93 percent as two non-ST-elevation MIs were not apparent).

RWMA were indicative of acute MI in only 31 percent of 87 patients.

Among the 88 patients without RWMA, only two (2.2 percent) subsequently "ruled in" for a non-ST-elevation MI by cardiac enzymes.

It may be impossible to distinguish RWMA due to acute ischemia from those due to a previous MI. One clue, the preservation of normal wall thickness and normal reflectivity, suggests an acute event, while a thin akinetic reflective segment suggests chronicity. Some authorities recommend utilization of left-sided contrast for better delineation of the endocardial border when standard views are difficult to interpret [17].

Two-dimensional, resting transthoracic echocardiography has been shown to have high sensitivity for the diagnosis of acute MI (93 percent) and ACS (88 percent), and moderate specificity for acute MI (78 percent) and ACS (53 percent) using regional dysfunction as the criteria for abnormality [16,18-21]. The performance characteristics of echocardiography are less optimal for the detection of ACS compared with acute MI, while the ED clinician faced with a decision on patient disposition is interested in identifying all ACS, including unstable angina as well as acute MI.

The predictive value of resting echocardiography within four hours of ED presentation was demonstrated in a study of 260 patients presenting to the ED with possible ACS. In this study, rest echocardiography predicted cardiac events (including acute MI and revascularization) with 91 percent sensitivity and 75 percent specificity [20]. When patients with abnormal ECGs were excluded, the sensitivity and specificity of rest echocardiography for predicting cardiac events was similar (85 and 74 percent, respectively). Other studies indicate that echocardiography performed after resolution of symptoms is unlikely to predict cardiac events [22].

The use of contrast agents can enhance endocardial detection for assessment of RWMA. Use of contrast agents to assess myocardial perfusion has also been investigated and found to be useful, but expertise is not widely available, especially in the emergency setting. (See "Contrast echocardiography: Clinical applications".)

A potential advantage of use of echocardiography in the ED setting is its ability to detect complications of MI as well as evidence of other causes of acute chest pain such as proximal aortic dissection, acute pericarditis, stress-induced cardiomyopathy, and pulmonary embolism, which may manifest echocardiographically as dilated and hypokinetic right ventricle and increased pulmonary artery pressure. Limitations of this approach include the fact that many patients become asymptomatic by the time of the test, thus decreasing its sensitivity; a normal test does not exclude important CAD.

rMPI versus echocardiography — Both rMPI and echocardiography may be useful for the patient with ongoing symptoms. The strength of evidence supporting a management strategy of potential ED discharge with a normal resting study may be higher with rMPI, based on the larger populations that have been reported and the consistently high negative predictive value compared with rest echocardiography.

The choice between these two should be made based on local expertise, availability, and cooperation among the various stakeholder groups, including ED clinicians, cardiologists, and imaging specialists. We believe that echocardiography is less useful in patients whose symptoms have resolved. Another advantage for rMPI is that imaging can be deferred for up to four hours after the injection of a Tc-99m tracer, making test logistics easier in busy departments.

Few studies directly compare rMPI and echocardiography in patients with ongoing chest pain. A study of 470 patients classified as having low to intermediate risk of ACS found that rest rMPI and rest echocardiography had similar sensitivities and specificities for prediction (ie, prognosis) of acute MI or coronary intervention (sensitivity 100 percent for both, specificity 89 percent for rMPI and 86 percent for echocardiography) [23]. Rest rMPI and rest echocardiography also performed similarly for prediction of acute MI, significant coronary artery stenosis, or positive stress rMPI (sensitivity 75 percent for both, specificity 88 percent for echocardiography and 90 percent for rMPI).

Coronary computed tomographic angiography — Coronary computed tomographic angiography (CCTA) should not be performed in patients with ongoing chest pain who may have ACS but may be done in patients who are symptom-free where ACS remains a concern. CCTA is discussed separately. (See "Cardiac imaging with computed tomography and magnetic resonance in the adult", section on 'Cardiac CT'.)

Cardiovascular magnetic resonance imaging — CMR imaging is another potential magnetic resonance method for identifying CAD in patients with chest pain. We see no advantage of this test in patients who can have 2D echocardiography or acute rest SPECT rMPI performed. While CMR can provide comprehensive information, the literature on its use in ED chest pain patients emanates from a small number of expert centers. In most centers it is likely that rMPI or echocardiography would be more readily available on short notice, and that expertise is more likely present.

CMR imaging may be helpful in diagnosing particular cases, such as suspected myocarditis, though this is often suspected after ACS due to CAD is ruled out. (See "Clinical manifestations and diagnosis of myocarditis in adults", section on 'Cardiovascular magnetic resonance'.)

Limitations of rest testing — There are significant limitations to the use of rest imaging with either echocardiography or acute rest SPECT rMPI in patients with ongoing chest pain:

Rest imaging is less helpful in diagnosing ACS in patients with prior MI, since the age of abnormalities may be uncertain unless a significant new defect is present and a prior study is available for comparison.

Acute rest rMPI can miss small areas of ischemia or MI, especially in the inferior wall [10].

The sensitivity for ACS is highest when the test is performed during active symptoms and progressively diminishes after symptom resolution. This is an important consideration in evaluation of ED patients who frequently present when symptoms have resolved. Evidence suggests that while regional dysfunction frequently resolves within minutes after resolution of ischemic symptoms, perfusion abnormalities may persist longer [8,24]. We recommend that rest tests not be performed if the patient has been pain free for more than three hours, although there may be instances in which a longer duration is acceptable. One example is a patient whose troponin has returned as equivocal for MI.

Another limitation of rMPI is the confounding influence of soft tissue attenuation artifacts. In the ED setting, in which only one set of images is acquired, gating is less useful to differentiate attenuation artifacts from true perfusion defects. However, use of gated images for assessment of left ventricular function with rest rMPI improved its predictive power [25].

PATIENTS WHOSE SYMPTOMS HAVE RESOLVED — For patients whose symptoms resolve, noninvasive cardiac stress (provocative) testing, with or without imaging, is performed on those for whom there remains a suspicion of an ACS despite normal or nondiagnostic ECG and two normal sensitive (conventional) troponin values. The definitions of sensitive and highly sensitive troponin are found elsewhere. (See "Troponin testing: Analytical considerations".)

Safe performance of provocative stress testing requires careful screening to assure that the patient is symptom free at rest and lacks evidence of myocardial necrosis or resting ischemia by serial biomarkers and ECGs.

Our approach — For hemodynamically stable, symptom-free patients with nonischemic ECGs and two normal troponins in whom there remains a concern for myocardial ischemia as the cause of the presenting symptom, a noninvasive testing strategy can further evaluate the patient. The selection of the test is based primarily on whether the patient can exercise and whether the ECG will be interpretable for new ischemic changes. (See 'Imaging or no imaging' below and "Selecting the optimal cardiac stress test", section on 'Our approach to choosing the optimal stress test'.)

As discussed below, the choice of test should also be influenced by factors such as local expertise and availability.

For patients who are likely to be able to exercise maximally and who have an interpretable ECG, we send the patient for exercise (stress) testing without imaging, which is generally performed prior to discharge.

For patients who are likely to be able to exercise maximally and whose exercise ECG is not likely to be valuable for risk prediction, the preferred test is an exercise stress test with either radionuclide myocardial perfusion imaging (rMPI) or echocardiographic imaging. The choice between the two depends on local expertise and availability.

For patients who are not likely to be able to exercise maximally, the patient is referred for pharmacologic stress testing with imaging.

At institutions where 64-slice (or higher) cardiac CT scanners and local expertise are available, rest imaging with CCTA can be used in symptom-free patients without ischemia on the ECG and one initial conventional troponin being negative. Since CCTA is performed when patients are in the resting state, serial troponin measurements are not necessary and one negative initial troponin would suffice.

Inpatient or outpatient — In patients with low risk of ACS, stress testing prior to discharge from the emergency department (ED) or observation unit is often preferred over discharge with early outpatient testing. However, early (within 72 hours) outpatient testing is an option in selected patients. An early outpatient stress test evaluation is a reasonable alternative to inpatient testing for the reliable and adherent patient with a low to intermediate pretest probability for ACS due to CAD (table 2) with low-risk features (table 3), provided the patients has at least two sets of negative cardiac biomarkers, has no evidence of ischemia on serial ECGs, has clinician follow-up, and has an outpatient stress test to be performed within 72 hours, which is scheduled prior to ED discharge [26-28].

One study supporting this approach included 971 patients ≥40 years old with chest pain and low risk for CAD who underwent outpatient stress testing within 72 hours [28]. Compliance with outpatient stress testing was 92 percent; no cardiac events (death, MI, or coronary intervention) were observed among those who were not compliant. Among 871 patients with six-month follow-up, 2 percent required coronary intervention, 0.2 percent had MI, 0.7 percent had normal stress test results after discharge but later required cardiac catheterization, and 0.6 percent returned to the ED for ongoing chest pain. Hospital admission rates decreased significantly from 31 to 26 percent after initiation of the protocol.

Outpatient stress testing should not be offered to patients at risk for poor compliance since such a strategy may lead to an increased rate of adverse cardiac events [29].

Choice of stress type — Exercise or pharmacologic agents can be used to stress the heart. The choice of the stress method depends upon the patient's ability to exercise (see "Selecting the optimal cardiac stress test"). Pharmacologic stress agents include vasodilators (eg, adenosine, dipyridamole, regadenoson) and dobutamine with or without atropine. In the United States, vasodilators are generally used in conjunction with rMPI and dobutamine plus atropine is generally used in conjunction with echocardiography. In Europe, vasodilator echocardiography is also performed.

For patients who are able to exercise maximally, exercise stress testing (exercise/supine bicycle echocardiography) has the ability to assess the patient's functional capacity.

For patients who are only able to exercise submaximally, conversion to pharmacologic stress testing should be considered if ischemic changes are not present at the end of a submaximal test.

For patients who are unable to exercise, pharmacologic stress testing (adenosine, dipyridamole, regadenoson, dobutamine) with imaging (scintigraphy or positron emission tomography [PET], echocardiography, or CMR) should be considered.

Studies have demonstrated the safety and utility of symptom-limited treadmill exercise ECG testing after 8 to 12 hours of evaluation in ED patients with low to intermediate risk for CAD [30-32]. A negative exercise stress test makes severe obstructive CAD unlikely, particularly if the patient is able to exercise with good functional capacity. An abnormal exercise treadmill test would warrant admission to the hospital and further diagnostic workup.

Imaging or no imaging — For patients who are able to maximally exercise and have resting ECGs that are interpretable for ST-segment changes, exercise ECG stress testing does not require the addition of imaging. Exercise can be performed using a standard treadmill or supine bicycle protocol. (See "Exercise ECG testing: Performing the test and interpreting the ECG results".)

For patients who are able to exercise maximally but whose exercise ECG is uninterpretable for ischemia, adding imaging allows for assessment of ischemic changes. Baseline ECG abnormalities that preclude ECG stress test interpretation include preexcitation (Wolff-Parkinson-White) syndrome, a paced ventricular rhythm, more than 1 mm of ST depression at rest, complete left bundle branch block, and patients using digoxin or with ECG criteria for left ventricular hypertrophy, even if they have less than 1 mm of baseline ST depression. In patients with such abnormalities, an imaging stress test is helpful for diagnosis and prognosis. (See "Exercise ECG testing: Performing the test and interpreting the ECG results".)

Choice of imaging modality — For patients who require imaging in addition to stress, the choice of stress imaging technique depends upon patient characteristics as well as local expertise and availability. (See "Selecting the optimal cardiac stress test".)

Stress imaging modalities that have been evaluated include rMPI (single photon emission CT [SPECT] and PET), echocardiography, and CMR.

Stress radionuclide myocardial perfusion imaging — Stress rMPI with either SPECT (image 1) or PET offers a significantly higher sensitivity for detection of CAD than exercise ECG testing without imaging [33,34]. In a study of 151 low-risk ED patients with chest pain, the sensitivity of exercise rMPI (95 percent) was higher than that of exercise ECG (28 percent); the specificities were 83 and 95 percent [33]. A limitation of SPECT or PET is that they both require ionizing radiation. (See "Prognostic features of stress testing in patients with known or suspected coronary disease".)

A prospective observational study of 2074 chest pain patients evaluated by an accelerated protocol including two-hour delta serum creatine kinase-MB and troponin I levels, serial ECGs, and rest and stress rMPI in those with a negative two-hour evaluation demonstrated high sensitivity (99 percent) and specificity (87 percent) for occurrence of ACS within 30 days [35].

In low-risk patients who can exercise, a selective stress-only (also called a "stress-first") strategy, preferably with attenuation correction, may be employed to obviate the need for a rest study when the stress portion is normal and thus facilitate early discharge, improve patient comfort, and reduce radiation dose [36].

Stress rMPI as a component of initial evaluation of acute chest pain may reduce the rate of return chest pain visits. Such a benefit was suggested by a study of 1195 ED chest pain patients with normal or nondiagnostic ECG and at least three negative serial troponin levels [37]. Patients with normal stress rMPI had a lower return visit rate at three months (4 percent) compared with those with abnormal rMPI studies (19 percent), or those without initial diagnostic evaluation (stress test or cardiac catheterization) (15 percent). In addition, patients who underwent initial diagnostic evaluation had a lower rate of acute MI or death in the three-month follow-up period.

The majority of studies of stress rMPI in acute chest pain patients have used SPECT. Despite some advantages, including more robust attenuation correction and improved performance characteristics in patients with obesity, the application of PET rMPI in this population is limited by lack of wide availability and the inability to perform PET rMPI using available tracers in conjunction with exercise stress.

Stress echocardiography — Stress echocardiography is an alternative to stress rMPI in this setting [38-40]. It is usually performed with either treadmill exercise or dobutamine.

Dobutamine stress echocardiography (DSE) is helpful for risk stratification in patients who are unable to exercise. In a study of 377 low-risk ED patients with negative work-up who underwent predischarge DSE, patients with a positive DSE had more than 10-fold risk of cardiac death, MI, rehospitalization for unstable angina, or revascularization compared with patients with a negative DSE [41].

The use of ultrasound contrast agents can enhance endocardial detection for assessment of regional wall motion abnormalities (RWMA). Use of contrast agents to assess myocardial perfusion has also been investigated but not routinely used. (See "Contrast echocardiography: Clinical applications" and "Contrast echocardiography: Contrast agents, safety, and imaging technique".)

Stress CMR — Pharmacologic (adenosine, dipyridamole, or dobutamine) CMR stress testing has also been used to detect ischemia from CAD with first pass perfusion defects, RWMA on cine images, and delayed hyperenhancement pattern after gadolinium administration [42,43]. (See "Clinical utility of cardiovascular magnetic resonance imaging", section on 'Pharmacologic stress CMR'.)

Limitations of this procedure include the absence of widespread expertise and facilities to perform comprehensive examinations, length of scan times (up to one hour), or the presence of a CMR-incompatible implantable cardioverter-defibrillator. Additionally, gadolinium is contraindicated in patients with kidney impairment or end-stage kidney failure (estimated glomerular filtration rate [eGFR] <30) due to the potential risk of rare but irreversible nephrogenic systemic sclerosis.

CMR can be used to diagnose conditions that mimic ACS, such as myocarditis or pericarditis. However, CMR is typically not performed during the initial phase of ACS assessment and should only be performed in select patients with suspicion for these entities. (See "Clinical manifestations and diagnosis of myocarditis in adults", section on 'Cardiovascular magnetic resonance' and "Acute pericarditis: Clinical presentation and diagnosis", section on 'Our approach to diagnostic testing'.)

Although multicenter studies have evaluated the accuracy of CMR imaging to identify CAD in patients referred for elective invasive coronary angiography, data are not sufficient to support clinical CMR imaging for the routine identification of coronary artery stenoses in patients with chest pain [42-45].

Coronary computed tomography angiography — An alternate approach to functional imaging is direct visualization of the coronary artery circulation to detect obstructive CAD (anatomy) by noninvasive coronary imaging using CCTA with at least 64-slice cardiac CT scanners (image 2). With this approach, the absence of obstructive CAD in a patient with chest pain is used to exclude ACS.

The principle limitation of CCTA is that a positive study (the presence of coronary artery stenoses) does not guarantee that unstable angina is the diagnosis. In patients with chest pain and known CAD, or in chest pain patients found to have intermediate degrees of coronary stenosis, functional testing may be required to establish or exclude myocardial ischemia as the cause of symptoms. The strength of CCTA is the near-perfect negative predictive value of a normal CCTA, which would effectively eliminate ACS as the cause of chest pain in approximately 50 percent of low- to intermediate-risk acute chest pain patients. (See "Cardiac imaging with computed tomography and magnetic resonance in the adult".)

Other potential limitations of the use of CCTA in this setting include:

Need for heart rate lowering agents such as beta blocker or calcium channel blockers to slow the heart rate for motion-free images (newer higher temporal resolution CT scanners, such as the dual-source CT scanner, do not require stringent heart rate control).

It is not recommended in patients with impaired renal function (creatinine elevation or reduced eGFR).

It is not recommended in the presence of significant arrhythmia or atrial fibrillation with slower temporal resolution scanners such as the 64-slice single-source CT scanners. Newer-generation CT scanners with better temporal resolution are able to produce motion-free images despite arrhythmia or rate-controlled atrial fibrillation.

Diagnostic accuracy, particularly specificity, may be reduced in patients with heavy coronary artery calcifications (eg, older patients).

Radiation exposure. (See "Radiation dose and risk of malignancy from cardiovascular imaging" and "Cardiac imaging with computed tomography and magnetic resonance in the adult".)

CCTA was evaluated in a 2013 meta-analysis of four randomized controlled trials [46-49] with 3266 low- to intermediate-risk patients that compared 64-slice CCTA with usual care triage of acute chest pain in the ED [50]. The ACRIN PA and ROMICAT II trials were the largest studies included in the above-mentioned meta-analysis. Patients were followed for six months in two trials [46,47] and for one month in two trials [48,49]. Average length of stay was significantly reduced with CCTA compared with usual care in all four studies. In the ROMICAT II trial, patients were referred for CCTA after return of the first negative troponin.

An earlier meta-analysis of nine observational studies with a total of 1559 low- to intermediate-risk patients presenting with possible ACS evaluated the accuracy of 64-slice coronary CT in predicting major adverse cardiac events (MACE; defined as MI, coronary revascularization, cardiac arrest, or death from an ACS) at 30 days [51]. A positive CCTA (at least 50 percent coronary stenosis) was identified in 14.8 percent of patients. The overall sensitivity and specificity of CCTA for prediction of MACE were 93.3 percent and 89.9 percent. The positive predictive value was 48.1 percent, and the negative predictive value was 99.3 percent.

Patient cooperation is particularly crucial for CCTA, since motion or breathing artifacts can invalidate a study that generally cannot be readily reacquired due to contrast and radiation dose considerations. However, CT scanner technology with wide detector volumetric scanning (eg, 256- or 320-slice CT scanners) can acquire whole heart imaging during one heartbeat, which reduces the need for stringent breathhold requirements [52]. Moreover, faster scanner technology (eg, dual-source CT) can be performed in patients with atrial fibrillation or uncontrolled tachycardia who cannot be effectively imaged with single-source CT [53]. Given improved scanner technology with short acquisition times and scanning algorithms with low radiation dose, repeat CCTA may be performed if deemed necessary by the cardiac imager or radiologist to obtain diagnostic images.

Professional guidelines for the evaluation and diagnosis of chest pain CCTA provide a Class I indication for its use in patients with acute chest pain without known CAD or prior testing and a Class IIa indication for patients who had prior inconclusive or mildly abnormal stress test ≤1 year from presentation [54]. In patients with known nonobstructive disease (<50 percent stenosis), CCTA has a Class IIa indication in the acute chest pain patient [54].

CT-derived fractional flow reserve (FFRCT) has become available at certain institutions and has been studied in the setting of acute chest pain [55,56]. FFRCT has the ability to identify lesion-specific ischemia. In a single-center study of 555 patients in the ED, FFRCT was feasible, and a negative FFRCT result was deemed safe for deferral of revascularization [56]. In the aforementioned chest pain guideline, if locally available, FFRCT has a Class 2a indication if CCTA showed either inconclusive or obstructive CAD (≥50 percent stenosis) [54]. However, FFRCT is expensive and not routinely available in the inpatient setting.

Comparison of tests — When considering which imaging test to choose for symptom-free patients at low to intermediate risk of ACS after two negative troponin values have been secured, several factors that should be taken into account: local expertise, availability, portability (use at the bedside), radiation dose, ease of applicability to the ED chest pain population, and cost (table 4). In most patients who will be referred for stress imaging, either rMPI or echocardiography is performed.

In addition, body habitus may influence decision making. rMPI is more tolerant of obesity or chronic obstructive pulmonary disease than echocardiography.

A potential advantage of echocardiography and CMR is that these methods may identify other thoracic causes of chest pain when ACS has been excluded. New rest wall motion abnormalities or other cardiac abnormalities (pericardial effusion in pericarditis, thoracic aortic dissection, etc) may be observed in a patient referred for stress echocardiography, obviating the need for stress testing.

The diagnostic accuracy of stress echocardiography was evaluated in a study of 503 acute chest pain patients who underwent both exercise stress echocardiography and exercise rMPI for detection of CAD. CAD was defined as >50 percent coronary artery stenosis on angiography or cardiac events (sudden death, nonfatal MI, revascularization) within six months. Stress echocardiography demonstrated similar sensitivity to stress rMPI (85 versus 86 percent), with slightly but significantly greater specificity (95 versus 90 percent) [57]. The sensitivity of exercise ECG was significantly lower (43 percent), although specificity was similar to that for stress echocardiography (95 percent).

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Non-ST-elevation acute coronary syndromes (non-ST-elevation myocardial infarction)".)

SUMMARY AND RECOMMENDATIONS

Patients with ongoing symptoms – For patients with ongoing chest pain who need further diagnostic testing, we recommend rest imaging with either two-dimensional (2D) echocardiography or radionuclide myocardial perfusion imaging (rMPI). For rest echocardiography, intravenous ultrasonic contrast agent should be used to optimize endocardial border detection if all segments are not well visualized. (See 'Patients with ongoing symptoms' above.)

Patients without symptoms – For patients who do not have high-risk findings (table 3), are symptom free for at least six hours, have no ECG signs of ischemia, and have negative serial troponin assays, either stress testing or coronary computed tomographic angiography (CCTA) is recommended to assess for obstructive coronary artery disease (CAD).

Patients who can exercise with normal ECG – Patients with the above characteristics with an ECG that is interpretable for ischemic changes should undergo exercise ECG testing rather than stress testing or CCTA. (See 'Patients whose symptoms have resolved' above and 'Choice of stress type' above.)

Uninterpretable ECG – Patients who have an uninterpretable ECG for ischemia (eg, left bundle branch block, ventricular paced rhythm, left ventricular hypertrophy with strain pattern, or digoxin use) should undergo exercise stress testing with imaging (either rMPI or echocardiography) or CCTA. Stress perfusion cardiovascular magnetic resonance (CMR) imaging is another option. (See 'Choice of imaging modality' above.)

Inability to exercise – Patients who are unable to exercise should undergo CCTA or pharmacologic stress testing combined with imaging (vasodilator stress rMPI or dobutamine stress echocardiography).

Timing of testing – Outpatient stress testing or CCTA is a reasonable alternative for appropriately screened patients with low probability of an acute coronary syndrome (ACS) due to CAD (table 2) who are compliant and reliable and have proper instructions with close follow-up with an outpatient stress test scheduled to be performed within 72 hours of emergency department (ED) discharge. (See 'Inpatient or outpatient' above.)

Other studies – CMR is not recommended for routine risk stratification of possible ACS. However, CMR may be helpful to establish a diagnosis in individual cases (eg, for suspected myocarditis) during the inpatient workup. (See 'Cardiovascular magnetic resonance imaging' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Christopher P Cannon, MD, who contributed as a section editor to earlier versions of this topic review.

  1. Pope JH, Aufderheide TP, Ruthazer R, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med 2000; 342:1163.
  2. Nesto RW, Kowalchuk GJ. The ischemic cascade: temporal sequence of hemodynamic, electrocardiographic and symptomatic expressions of ischemia. Am J Cardiol 1987; 59:23C.
  3. Kaul S, Senior R, Firschke C, et al. Incremental value of cardiac imaging in patients presenting to the emergency department with chest pain and without ST-segment elevation: a multicenter study. Am Heart J 2004; 148:129.
  4. Tong KL, Kaul S, Wang XQ, et al. Myocardial contrast echocardiography versus Thrombolysis In Myocardial Infarction score in patients presenting to the emergency department with chest pain and a nondiagnostic electrocardiogram. J Am Coll Cardiol 2005; 46:920.
  5. Jeroudi MO, Cheirif J, Habib G, Bolli R. Prolonged wall motion abnormalities after chest pain at rest in patients with unstable angina: a possible manifestation of myocardial stunning. Am Heart J 1994; 127:1241.
  6. Gerber BL, Wijns W, Vanoverschelde JL, et al. Myocardial perfusion and oxygen consumption in reperfused noninfarcted dysfunctional myocardium after unstable angina: direct evidence for myocardial stunning in humans. J Am Coll Cardiol 1999; 34:1939.
  7. Bilodeau L, Théroux P, Grégoire J, et al. Technetium-99m sestamibi tomography in patients with spontaneous chest pain: correlations with clinical, electrocardiographic and angiographic findings. J Am Coll Cardiol 1991; 18:1684.
  8. Varetto T, Cantalupi D, Altieri A, Orlandi C. Emergency room technetium-99m sestamibi imaging to rule out acute myocardial ischemic events in patients with nondiagnostic electrocardiograms. J Am Coll Cardiol 1993; 22:1804.
  9. Kontos MC, Jesse RL, Schmidt KL, et al. Value of acute rest sestamibi perfusion imaging for evaluation of patients admitted to the emergency department with chest pain. J Am Coll Cardiol 1997; 30:976.
  10. Heller GV, Stowers SA, Hendel RC, et al. Clinical value of acute rest technetium-99m tetrofosmin tomographic myocardial perfusion imaging in patients with acute chest pain and nondiagnostic electrocardiograms. J Am Coll Cardiol 1998; 31:1011.
  11. Tatum JL, Jesse RL, Kontos MC, et al. Comprehensive strategy for the evaluation and triage of the chest pain patient. Ann Emerg Med 1997; 29:116.
  12. Udelson JE, Beshansky JR, Ballin DS, et al. Myocardial perfusion imaging for evaluation and triage of patients with suspected acute cardiac ischemia: a randomized controlled trial. JAMA 2002; 288:2693.
  13. Hauser AM, Gangadharan V, Ramos RG, et al. Sequence of mechanical, electrocardiographic and clinical effects of repeated coronary artery occlusion in human beings: echocardiographic observations during coronary angioplasty. J Am Coll Cardiol 1985; 5:193.
  14. Wohlgelernter D, Cleman M, Highman HA, et al. Regional myocardial dysfunction during coronary angioplasty: evaluation by two-dimensional echocardiography and 12 lead electrocardiography. J Am Coll Cardiol 1986; 7:1245.
  15. Beller GA. Myocardial perfusion imaging for detection of silent myocardial ischemia. Am J Cardiol 1988; 61:22F.
  16. Sabia P, Afrookteh A, Touchstone DA, et al. Value of regional wall motion abnormality in the emergency room diagnosis of acute myocardial infarction. A prospective study using two-dimensional echocardiography. Circulation 1991; 84:I85.
  17. Lang RM, Bierig M, Devereux RB, et al. Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005; 18:1440.
  18. Peels CH, Visser CA, Kupper AJ, et al. Usefulness of two-dimensional echocardiography for immediate detection of myocardial ischemia in the emergency room. Am J Cardiol 1990; 65:687.
  19. Sasaki H, Charuzi Y, Beeder C, et al. Utility of echocardiography for the early assessment of patients with nondiagnostic chest pain. Am Heart J 1986; 112:494.
  20. Kontos MC, Arrowood JA, Paulsen WH, Nixon JV. Early echocardiography can predict cardiac events in emergency department patients with chest pain. Ann Emerg Med 1998; 31:550.
  21. Lewis WR. Echocardiography in the evaluation of patients in chest pain units. Cardiol Clin 2005; 23:531.
  22. Lim SH, Sayre MR, Gibler WB. 2-D echocardiography prediction of adverse events in ED patients with chest pain. Am J Emerg Med 2003; 21:106.
  23. Paventi S, Parafati MA, Luzio ED, Pellegrino CA. Usefulness of two-dimensional echocardiography and myocardial perfusion imaging for immediate evaluation of chest pain in the emergency department. Resuscitation 2001; 49:47.
  24. Fram DB, Azar RR, Ahlberg AW, et al. Duration of abnormal SPECT myocardial perfusion imaging following resolution of acute ischemia: an angioplasty model. J Am Coll Cardiol 2003; 41:452.
  25. Kontos MC, Haney A, Ornato JP, et al. Value of simultaneous functional assessment in association with acute rest perfusion imaging for predicting short- and long-term outcomes in emergency department patients with chest pain. J Nucl Cardiol 2008; 15:774.
  26. Anderson, JL, Adams, CD, Antman, EM, et al. ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-Elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine. J Am Coll Cardiol 2007; 50:e1. www.acc.org/qualityandscience/clinical/statements.htm (Accessed on July 28, 2008).
  27. Richards D, Meshkat N, Chu J, et al. Emergency department patient compliance with follow-up for outpatient exercise stress testing: a randomized controlled trial. CJEM 2007; 9:435.
  28. Meyer MC, Mooney RP, Sekera AK. A critical pathway for patients with acute chest pain and low risk for short-term adverse cardiac events: role of outpatient stress testing. Ann Emerg Med 2006; 47:427.
  29. Manini AF, Gisondi MA, van der Vlugt TM, Schreiber DH. Adverse cardiac events in emergency department patients with chest pain six months after a negative inpatient evaluation for acute coronary syndrome. Acad Emerg Med 2002; 9:896.
  30. Stein RA, Chaitman BR, Balady GJ, et al. Safety and utility of exercise testing in emergency room chest pain centers: An advisory from the Committee on Exercise, Rehabilitation, and Prevention, Council on Clinical Cardiology, American Heart Association. Circulation 2000; 102:1463.
  31. Zalenski RJ, McCarren M, Roberts R, et al. An evaluation of a chest pain diagnostic protocol to exclude acute cardiac ischemia in the emergency department. Arch Intern Med 1997; 157:1085.
  32. Amsterdam EA, Kirk JD, Diercks DB, et al. Immediate exercise testing to evaluate low-risk patients presenting to the emergency department with chest pain. J Am Coll Cardiol 2002; 40:251.
  33. Conti A, Gallini C, Costanzo E, et al. Early detection of myocardial ischaemia in the emergency department by rest or exercise (99m)Tc tracer myocardial SPET in patients with chest pain and non-diagnostic ECG. Eur J Nucl Med 2001; 28:1806.
  34. Candell-Riera J, Oller-Martínez G, de León G, et al. Yield of early rest and stress myocardial perfusion single-photon emission computed tomography and electrocardiographic exercise test in patients with atypical chest pain, nondiagnostic electrocardiogram, and negative biochemical markers in the emergency department. Am J Cardiol 2007; 99:1662.
  35. Fesmire FM, Hughes AD, Fody EP, et al. The Erlanger chest pain evaluation protocol: a one-year experience with serial 12-lead ECG monitoring, two-hour delta serum marker measurements, and selective nuclear stress testing to identify and exclude acute coronary syndromes. Ann Emerg Med 2002; 40:584.
  36. Depuey EG, Mahmarian JJ, Miller TD, et al. Patient-centered imaging. J Nucl Cardiol 2012; 19:185.
  37. Shoyeb A, Bokhari S, Sullivan J, et al. Value of definitive diagnostic testing in the evaluation of patients presenting to the emergency department with chest pain. Am J Cardiol 2003; 91:1410.
  38. Trippi JA, Lee KS, Kopp G, et al. Dobutamine stress tele-echocardiography for evaluation of emergency department patients with chest pain. J Am Coll Cardiol 1997; 30:627.
  39. Bergeron S, Ommen SR, Bailey KR, et al. Exercise echocardiographic findings and outcome of patients referred for evaluation of dyspnea. J Am Coll Cardiol 2004; 43:2242.
  40. Buchsbaum M, Marshall E, Levine B, et al. Emergency department evaluation of chest pain using exercise stress echocardiography. Acad Emerg Med 2001; 8:196.
  41. Bholasingh R, Cornel JH, Kamp O, et al. Prognostic value of predischarge dobutamine stress echocardiography in chest pain patients with a negative cardiac troponin T. J Am Coll Cardiol 2003; 41:596.
  42. Miller CD, Hwang W, Hoekstra JW, et al. Stress cardiac magnetic resonance imaging with observation unit care reduces cost for patients with emergent chest pain: a randomized trial. Ann Emerg Med 2010; 56:209.
  43. Miller CD, Hwang W, Case D, et al. Stress CMR imaging observation unit in the emergency department reduces 1-year medical care costs in patients with acute chest pain: a randomized study for comparison with inpatient care. JACC Cardiovasc Imaging 2011; 4:862.
  44. Miller CD, Case LD, Little WC, et al. Stress CMR reduces revascularization, hospital readmission, and recurrent cardiac testing in intermediate-risk patients with acute chest pain. JACC Cardiovasc Imaging 2013; 6:785.
  45. Miller CD, Hoekstra JW, Lefebvre C, et al. Provider-directed imaging stress testing reduces health care expenditures in lower-risk chest pain patients presenting to the emergency department. Circ Cardiovasc Imaging 2012; 5:111.
  46. Goldstein JA, Gallagher MJ, O'Neill WW, et al. A randomized controlled trial of multi-slice coronary computed tomography for evaluation of acute chest pain. J Am Coll Cardiol 2007; 49:863.
  47. Goldstein JA, Chinnaiyan KM, Abidov A, et al. The CT-STAT (Coronary Computed Tomographic Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment) trial. J Am Coll Cardiol 2011; 58:1414.
  48. Litt HI, Gatsonis C, Snyder B, et al. CT angiography for safe discharge of patients with possible acute coronary syndromes. N Engl J Med 2012; 366:1393.
  49. Hoffmann U, Truong QA, Schoenfeld DA, et al. Coronary CT angiography versus standard evaluation in acute chest pain. N Engl J Med 2012; 367:299.
  50. Hulten E, Pickett C, Bittencourt MS, et al. Outcomes after coronary computed tomography angiography in the emergency department: a systematic review and meta-analysis of randomized, controlled trials. J Am Coll Cardiol 2013; 61:880.
  51. Takakuwa KM, Keith SW, Estepa AT, Shofer FS. A meta-analysis of 64-section coronary CT angiography findings for predicting 30-day major adverse cardiac events in patients presenting with symptoms suggestive of acute coronary syndrome. Acad Radiol 2011; 18:1522.
  52. Hsiao EM, Rybicki FJ, Steigner M. CT coronary angiography: 256-slice and 320-detector row scanners. Curr Cardiol Rep 2010; 12:68.
  53. Wang Y, Zhang Z, Kong L, et al. Dual-source CT coronary angiography in patients with atrial fibrillation: comparison with single-source CT. Eur J Radiol 2008; 68:434.
  54. Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation 2021; 144:e368.
  55. Ferencik M, Lu MT, Mayrhofer T, et al. Non-invasive fractional flow reserve derived from coronary computed tomography angiography in patients with acute chest pain: Subgroup analysis of the ROMICAT II trial. J Cardiovasc Comput Tomogr 2019; 13:196.
  56. Chinnaiyan KM, Safian RD, Gallagher ML, et al. Clinical Use of CT-Derived Fractional Flow Reserve in the Emergency Department. JACC Cardiovasc Imaging 2020; 13:452.
  57. Conti A, Sammicheli L, Gallini C, et al. Assessment of patients with low-risk chest pain in the emergency department: Head-to-head comparison of exercise stress echocardiography and exercise myocardial SPECT. Am Heart J 2005; 149:894.
Topic 5307 Version 31.0

References

آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟