ACS Investigations Flashcards
(124 cards)
1
Q
What does the chest radiograph indicate in ACS?
A
It does not have typical findings but can provide ancillary information, such as mediastinal width and pulmonary congestion.
Mediastinal width is an insensitive sign of aortic dissection, and pulmonary congestion is seen in heart failure.
2
Q
What is the significance of heart failure on the chest radiograph in AMI patients?
A
Its presence indicates higher risk and increased mortality, as it is found in one-third of AMI patients.
These patients may benefit from an aggressive therapeutic approach.
3
Q
What does a normal heart size in AMI patients with pulmonary edema indicate?
A
It usually indicates no past history of CHF.
AMI is the most frequent cause of pulmonary edema with a normal cardiac size.
4
Q
What factors are frequently associated with AMI and cardiomegaly?
A
- Preexisting history of CHF
- Anterior wall infarct
- Multiple-vessel CAD
5
Q
What role do biochemical markers play in ACS?
A
They are pivotal for diagnosis, risk stratification, and guidance of treatment.
Troponins indicate irreversible cell damage.
6
Q
What are the criteria for AMI diagnosis according to the European Society of Cardiology?
A
They are based on biochemical grounds, particularly focusing on specific markers like troponins.
7
Q
What does an early elevation of serum markers specific for myocardial necrosis confirm?
A
It confirms a presumptive diagnosis of NSTEMI.
8
Q
True or False: A single initial serum marker level is sufficient for ruling out acute coronary events.
A
False.
9
Q
What improves the sensitivity of serum marker tests for AMI?
A
Serial testing.
10
Q
What is the role of cardiac troponin (cTn) in evaluating ACS?
A
It is superior in sensitivity and specificity to other biomarkers and is referenced in the universal definition of MI.
11
Q
What proteins make up cardiac troponin?
A
- Myocardial troponin I (TnI)
- Troponin T (TnT)
12
Q
What triggers the biphasic rise in serum troponin levels after myocardial injury?
A
The early release of free cytoplasmic proteins followed by a slower rise from breakdown of muscle fiber.
13
Q
How long can troponin levels remain elevated after myocardial injury?
A
For 5 to 7 days.
14
Q
What defines an elevated troponin level?
A
Exceeding the 99th percentile in a healthy population.
15
Q
What is the limitation of a single standard troponin test in the early hours of symptom onset?
A
It has limited value in excluding AMI and cannot detect unstable angina.
16
Q
What is a high-sensitivity troponin (hsT) assay?
A
An assay that results in reportable levels of troponin in greater than 50% of healthy subjects.
17
Q
What association exists between detectable hsT levels and patient outcomes?
A
They are associated with the presence of structural heart disease and all-cause mortality.
18
Q
What protocol has the European Society of Cardiology recommended for patients with chest pain?
A
A 1-hour serial marker protocol.
19
Q
What cardiac conditions can lead to elevated troponin levels without ACS?
A
- Myocarditis
- Pericarditis
- CHF
- LVH
- Nonpenetrating cardiac trauma
20
Q
What noncardiac conditions can cause troponin elevation?
A
- Extreme physical exertion
- Renal insufficiency
- Multiple trauma
21
Q
How are elevated troponin levels related to pulmonary emboli?
A
They may result from right ventricular dysfunction and myocyte injury.
22
Q
In what patient population are elevated troponin levels commonly seen?
A
Asymptomatic patients with end-stage renal disease.
23
Q
What is the significance of elevated troponin levels in renal failure?
A
They are associated with increased risk of death and major cardiac and vascular morbidity.
24
Q
What should be done in unclear circumstances regarding elevated troponin levels?
A
Measure a repeat troponin level.
25
What is the disease studied with creatine kinase (single)?
AMI
## Footnote
AMI stands for acute myocardial infarction.
26
How many studies were conducted for creatine kinase (single) testing?
12 studies (3195 subjects)
## Footnote
This indicates the number of studies and total subjects analyzed.
27
What is the sensitivity of creatine kinase (single) testing for AMI?
37% (31–44)
## Footnote
The percentage indicates the test's ability to correctly identify those with the disease.
28
What is the specificity of creatine kinase (single) testing for AMI?
87% (80–91)
## Footnote
The percentage indicates the test's ability to correctly identify those without the disease.
29
What is the disease studied with CK-MB (presentation)?
ACS
## Footnote
ACS stands for acute coronary syndrome.
30
What is the prevalence range for CK-MB (presentation) testing?
20%
## Footnote
This indicates the prevalence of the disease in the studied population.
31
What is the specificity of CK-MB (presentation) testing for ACS?
96%
## Footnote
Indicates high specificity for the presentation test.
32
What is the sensitivity of CK-MB (serial) testing for AMI?
79% (71–86)
## Footnote
This shows the effectiveness of the serial testing method.
33
How many studies were conducted for myoglobin (presentation) testing?
18 studies (4172 subjects)
## Footnote
This indicates the number of studies and total subjects analyzed.
34
What is the sensitivity of myoglobin (presentation) testing for AMI?
49% (43–55)
## Footnote
Reflects the test's ability to identify AMI cases.
35
What is the specificity of myoglobin (presentation) testing for AMI?
91% (87–94)
## Footnote
Indicates the reliability of the test in ruling out non-AMI cases.
36
What is the sensitivity of troponin I (serial) testing for AMI?
90–100%
## Footnote
Indicates a very high sensitivity for this type of testing.
37
What is the specificity of troponin T (serial) testing for AMI?
85% (76–91)
## Footnote
This shows the reliability of the test in correctly identifying non-AMI cases.
38
What is the combined test of CK-MB and myoglobin (presentation) sensitivity for AMI?
83% (51–96)
## Footnote
Indicates the effectiveness of the combined test approach.
39
What is the specificity of exercise stress ECG testing for ACS?
82–93%
## Footnote
This range indicates the reliability of the exercise stress ECG test.
40
What is the sensitivity of rest echocardiography for AMI?
93% (81–91)
## Footnote
Reflects the effectiveness of rest echocardiography in identifying AMI.
41
How many studies were conducted for stress echocardiography?
1 study (139 subjects)
## Footnote
Indicates the number of studies and total subjects analyzed.
42
What is the specificity of sestamibi (rest) testing for ACS?
73% (56–85)
## Footnote
Indicates the reliability of this test for ACS diagnosis.
43
What does CK-MB stand for?
Creatine phosphokinase MB fraction
## Footnote
This is a specific enzyme tested in diagnosing AMI.
44
True or False: The sensitivity of troponin I (presentation) for AMI is 39% (10–78).
True
## Footnote
Indicates the sensitivity range for this specific test.
45
What is creatinine phosphokinase (CK) and where is it found?
CK is found in large quantities in cardiac muscle, skeletal muscle, brain, kidney, lung, and GI tract.
46
What does the appearance of CK-MB in the serum suggest?
It is highly suggestive of myocardial infarction (MI).
47
When is CK-MB detectable in the serum after myocardial injury?
CK-MB is detectable as early as 3 hours after necrosis onset, peaks at 20 to 24 hours, and normalizes in 2 to 3 days.
48
What conditions can lead to elevated CK-MB levels aside from myocardial injury?
* Trauma
* Muscular dystrophies
* Myositis
* Rhabdomyolysis
* Vigorous exercise
49
Why is CK-MB used rarely in contemporary emergency departments?
Due to the lack of specificity and the increased sensitivity of troponin level assays.
50
What is myoglobin and when does its level rise after myocardial injury?
Myoglobin is a small protein found in muscle tissue that rises in the initial 1 to 2 hours after injury.
51
How long does it take for myoglobin levels to return to baseline after myocardial injury?
Myoglobin levels return to baseline by 24 hours.
52
Why has myoglobin fallen out of favor as a marker for myocardial injury?
Due to its lack of specificity for myocardial injury.
53
What are some potential new cardiac markers for necrosis being developed?
* Heart-type, fatty acid–binding protein
* Ischemia-modified albumin
* Unbound free fatty acid
* Whole blood choline levels
54
What are C-reactive protein (CRP) and high-sensitivity CRP (hsCRP) used for?
They are inflammatory markers with prognostic value for cardiac events.
55
What does elevated plasma levels of myeloperoxidase predict?
It predicts the short-term risk of adverse cardiac events.
56
What markers are associated with hemodynamic status in ACS evaluation?
* B-type natriuretic peptide (BNP)
* NT-proBNP (N-terminal pro-BNP)
57
What is the primary use of BNP in clinical settings?
It is used as a marker for heart failure.
58
What is the negative predictive value of exercise stress testing for low-risk patients?
The negative predictive value is 98.7% for diagnosing ACS or cardiac events within 30 days.
59
What are the conditions under which exercise stress testing can be performed?
When patients are free of active ischemic or heart failure symptoms for a minimum of 8 to 12 hours.
60
What can cause false-positive results in exercise stress testing?
* Aortic stenosis or insufficiency
* Hypertrophic cardiomyopathy
* Hypertension
* LVH
* Digitalis toxic states
* Others
61
What does two-dimensional echocardiography detect in patients with ACS?
It detects regional wall motion abnormalities associated with impaired myocardial blood flow.
62
What is the significance of the absence of segmental abnormalities in echocardiography?
It has a high negative predictive value, up to 98% for suspected myocardial infarction.
63
What is the role of stress echocardiography after an AMI?
It assesses myocardial viability and ventricular function early after an AMI.
64
What does myocardial contrast echocardiography (MCE) assess?
MCE assesses microvascular perfusion and regional function.
65
What are the technical limitations of echocardiography in the ED?
* Expertise of the operator
* Expertise of the reader
* Inability to distinguish among ischemia, AMI, or old infarction
66
What is the clinical value of MCE in the ED setting?
The clinical value remains uncertain despite reports of low rates of adverse cardiac events.
67
Emergency Department
Bedside Echocardiography in Acute Coronary
Syndrome—Pros and Cons
**PROS:**
* Readily accessible, portable
* Inexpensive
* Safe, noninvasive
* Detection of wall motion
abnormalities, useful for early
diagnosis and presentations
involving diagnostic uncertainty
* Identification of nonischemic
causes of symptoms
**CONS**
* Skill level—operator- and
interpreter-dependent
* Limited sensitivity, particularly in
small areas of myocardial injury
* Limited visual windows in ≈10% of
patients
* Inability to distinguish acute wall
motion abnormalities from chronic
68
What is coronary computed tomography angiography (CCTA)?
A noninvasive modality to assess for coronary artery disease in patients ruled out for AMI and other active forms of ACS.
## Footnote
CCTA provides information about coronary anatomy and stenosis similar to cardiac catheterization.
69
How accurate is CCTA in detecting coronary artery obstructive lesions?
Very high accuracy for significant coronary artery obstructive lesions with high-resolution, newer-generation CT.
## Footnote
A meta-analysis supports this high accuracy.
70
In which patients is CCTA an appropriate imaging study?
Symptomatic stable patients with low to intermediate pretest probability of CAD.
## Footnote
CCTA is predictive of outcomes and has a low incidence of MACE in negative cases.
71
What is the incidence of MACE in patients with low to intermediate-risk chest pain and negative CCTA?
Very low (<1%) incidence of MACE at 1 year.
## Footnote
MACE stands for major adverse cardiovascular events.
72
What are the radiation dose ranges for CCTA?
2.0 to 5 mSv.
## Footnote
Standard CT scanning and cardiac catheterization are associated with 9 mSv and 12 mSv, respectively.
73
What is the role of beta-blockade in CCTA?
To optimize imaging quality before imaging.
## Footnote
Significant expertise is required for interpretation of CCTA.
74
What are the GRACE risk model and TIMI risk score used for?
Risk stratification in inpatients, examining the need for invasive therapy.
## Footnote
Neither was designed for patients with undifferentiated chest pain.
75
What is the EDACS score used for?
To identify low-risk individuals eligible for discharge from the emergency department.
## Footnote
It considers demographic, historical, and complaint descriptors.
76
What factors are included in the EDACS risk calculation?
Patient age, sex, history of CAD, CAD risk factors, and chest pain descriptors.
## Footnote
Higher risk factors include diaphoresis and pain radiation.
77
What defines a history of CAD in the EDACS risk calculation?
Previous AMI, CABG, or PCI.
## Footnote
CAD risk factors include dyslipidemia, diabetes, hypertension, current smoking, and family history.
78
What MACE rates are associated with low-risk patients identified by EDACS?
Low-risk patients with two negative troponin values can be safely discharged.
## Footnote
This includes an ECG without new ischemic changes.
79
What is the HEART Score?
A prediction model for identifying low-risk patients suitable for ED discharge after a limited evaluation.
## Footnote
Developed in the Netherlands for patients with chest pain suspected of AMI.
80
What variables are used to calculate the HEART Score?
History of chest pain event, ECG, patient age, risk factor burden, and serum troponin determination.
## Footnote
Scoring ranges from 0 to 2 for each variable.
81
What MACE rate is associated with low-risk patients (HEART Score 3 or less)?
1.7% MACE rate.
## Footnote
Low-risk patients are appropriate for discharge without additional cardiac evaluation.
82
What MACE rates are associated with intermediate-risk and high-risk groups in the HEART Score?
Intermediate-risk: 12% to 17% MACE rate; High-risk: 50% to 65% MACE rate.
## Footnote
High-risk patients may require coronary intervention.
83
What is the HEART Pathway?
A combination of the HEART Score with an additional troponin obtained at 3 hours for improved diagnostic accuracy.
## Footnote
It categorizes patients into lower and higher risk groups.
84
What are the three evaluation-strategy groups in the HEART Pathway?
* Early ED discharge with short-term follow-up
* Observation unit or short-term admission
* Inpatient admission with cardiology evaluation
## Footnote
This is based on the HEART Score and troponin results.
85
What is the importance of clinician judgment in applying decision tools like EDACS and HEART?
These tools do not dictate evaluation or management strategies and should be used alongside clinician assessment.
## Footnote
Treatment is guided by patient condition and local resource availability.
86
What is the score for a nonspecific history for ACS in the HEART Score?
0
87
What is the score for a specific history for ACS in the HEART Score?
2
88
What does an entirely normal ECG score in the HEART Score indicate?
0
89
What ECG abnormalities score 1 in the HEART Score?
Abnormal ECG, with repolarization abnormalities yet lacking significant ST depression
90
What ECG abnormalities score 2 in the HEART Score?
Abnormal ECG, with significant ST deviation (depression ± elevation)
91
What age range scores 1 point in the HEART Score?
Age between 45 & 64 years
92
What age category scores 2 points in the HEART Score?
Age 65 years or older
93
What is the score for no risk factors in the HEART Score?
0
94
How many risk factors score 1 point in the HEART Score?
1 to 2 risk factors
95
What is the score for 3 or more risk factors in the HEART Score?
2
96
What troponin level indicates a score of 0 in the HEART Score?
Troponin < discriminative level ± AccuTroponin I < 0.04 ng/ml
97
What troponin level indicates a score of 1 in the HEART Score?
Troponin elevated 1–3 times discriminative level ± AccuTroponin I 0.04-0.12 ng/ml
98
What troponin level indicates a score of 2 in the HEART Score?
Troponin elevated > 3 times discriminative level ± AccuTroponin I > 0.12 ng/ml
99
What is the risk category and management strategy for a total HEART Score of 0–3?
Low risk, potential candidate for early discharge
100
What is the risk category for a total HEART Score of 4–6?
Moderate risk, potential candidate for observation & further evaluation
101
What is the risk category for a total HEART Score of 7–10?
High risk, candidate for urgent or emergent intervention
102
What does the acronym CAD stand for in the context of the HEART Score?
Coronary Artery Disease
103
Fill in the blank: An abnormal ECG with significant ST deviation scores _____ in the HEART Score.
2
104
True or False: A history that contains only traditional elements of typical ACS presentation scores the highest in the HEART Score.
True
105
What are two examples of risk factors that can score in the HEART Score?
* DM
* Tobacco smoker
* HTN
* Hypercholesterolemia
* Obesity
* Family history of CAD
106
What additional conditions can contribute to a score of 2 for risk factors in the HEART Score?
Documented cardiac or systemic atherosclerotic vascular disease
107
What are the three distinct phases of care in the ED evaluation of chest pain with suspected ACS?
1. STEMI recognition
2. Rule-out of ACS
3. Consideration of significant CAD
## Footnote
These phases guide the assessment and management of patients with chest pain in the emergency department.
108
What is the primary diagnostic consideration during the STEMI recognition phase?
Rapid performance and competent interpretation of the 12-lead ECG
## Footnote
This is crucial for timely activation of hospital resources for patients suspected of having STEMI.
109
How long does the STEMI recognition phase typically last?
Less than 10 minutes
110
What happens if STEMI is not found during the evaluation?
The second phase focuses on a traditional rule-out MI approach with clinical monitoring and serial ECGs and serum marker determinations.
111
What percentage of patients with chest pain can be safely evaluated in the ED or observation unit and discharged home?
Approximately 75% to 80%
112
What are the cost implications of expedited ED evaluations without hospital admissions?
Result in significant cost savings, appropriate resource utilization, and avoidance of complications related to hospital stays.
113
What is the duration range for the final evaluation phase based on serum marker determination strategy?
From 1 hour with one troponin sampling up to approximately 12 hours with serial serum biomarker assessments.
114
What factors influence the consideration of significant CAD in the final evaluation phase?
Patient presentation features, patient stability, physician judgment, local medical resources, local resource availability, and patient desires.
115
List the potential dispositions for patients in the final evaluation phase.
* ED discharge with no further outpatient evaluation needed
* Outpatient follow-up with primary care physician or cardiologist
* Continued additional ED or observation unit evaluation with or without cardiology consultation
* Inpatient admission with continued diagnostic evaluation
116
What clinical decision rules can be used for patient risk stratification?
* EDACS-ADP
* HEART Score
* HEART Pathway
117
How are high-risk patients managed during the evaluation?
With inpatient admission or expeditious transfer to a resource-appropriate facility.
118
What methods are used to identify intermediate- and low-risk patients?
Qualitative and quantitative methods, including physician gestalt and diagnostic study results.
119
What is the strategy for evaluating intermediate-risk patients?
Continued evaluation during the hospital visit, which can occur in the ED, an observation unit, or as an inpatient.
120
What diagnostic approaches are employed for intermediate-risk patients?
* Stress testing
* Echocardiography
* Coronary CT angiography
* Myocardial scintigraphy
121
What is the outcome of studies comparing the observation unit approach to traditional hospital admission for MI rule-out?
Significant reduction in hospital admissions with no increase in adverse events.
122
How are low-risk patients typically managed after evaluation?
They can be managed as outpatients with follow-up from either a primary care physician or cardiologist.
123
Fill in the blank: Patients with a low _______ score, HEART score, or HEART Pathway result are safely discharged from the ED.
EDACS-ADP
124
What options do outpatient physicians have for further evaluation of low-risk patients?
* Exercise stress testing
* Nuclear imaging
* Echocardiography
* Coronary CT angiography
