1. Modalities of Cardiac Stress Test
Tiffany T. Nguyen MD
April 2014

2. Objectives
To understand the indications and contraindications for stress testing.
To learn the different modalities of cardiac stress test.
To effectively select the optimal cardiac stress test for each patient.

3. Indications Who to stress? Symptoms suggesting angina.
Acute chest pain
Recent ACS after 3 months of conservative therapy
Known CHD and change in clinical status.
Prior coronary revascularization.
Valvular heart disease.
New heart failure or cardiomyopathy.
Chronic left ventricular dysfunction and CHD who are candidates for revascularization.
Selected arrhythmias
Undergoing non-urgent non-cardiac surgery.

4. Contraindications Who NOT to stress? Unstable angina
Acute myocardial infarction
Arrhythmia with hemodynamic instability
Aortic dissection
Symptomatic aortic stenosis
Symptomatic severe heart failure
Pulmonary embolism
Myocarditis, Pericarditis
Bottom line is do not stress while patient is symptomatic or if there is evidence of hemodynamic instability

5. Pre-Test Probability Age Nonanginal pain Atypical angina
ACC/AHA 2012 Guidelines
Low probability - <10% - no further testing, except for prognostic information.
Intermediate probability % - non-invasive testing for diagnosis (exercise ECG as first modality).
High probability - >90% - non invasive testing for prognosis/management prior to cardiac cath.
Age
Nonanginal pain
Atypical angina
Typical angina
Men
Women
30-39 4% 2%
34%
12%
76%
26%
40-49
13% 3%
51%
22%
87%
55%
50-59
20% 7%
65%
31%
93%
73%
60-69
27%
14%
72%
94%
86%
Please refer to CHEST PAIN mini lecture to determine if nonanginal vs atypical vs typical.
It is important to keep in mind the pre-test probability of ACS when patient a presents with chest pain.
Patient with low pre-test probability may not need cardiac stress test for diagnosis. However, there is prognostic implication for stress test.
Stress test is indicated for all intermediate probability for diagnosis, with exercise ECG as first recommended modality.
For patient with high pre-test probability, stress test is recommended not for diagnosis but for prognosis and guide invasive therapy (cath vs cabg).

6. Two Components Each cardiac imaging modality has two components:
Stressing agent: treadmill, dobutamine, or adenosine
Imaging agent: EKG, echo, or radionuclide tracer (thallium or technetium)
Think of cardiac stress test as a combination of two components:
How am I going to stress the heart?
How can I collect information regarding the stressed heart?

7. Stressing Agents
Stressor
Pro
Con
Treadmill
Physiologic, simple, less expensive, good for patient who can walk
Dobutamine
No exercise needed
Caution in patients with arrhythmias
Adenosine or dipyridamole (used with nuclear)
No exercise needed; uncomfortable sensation of “heart stoppage”
Adenosine may induce bronchospasm – caution in COPD and asthma!
Slide courtesy of Dr. Varaz Bozoghlanian (Chief Resident )
Dobutamine is a synthetic catecholamine that stimulates B1 receptor to increase HR and Contractility.
Contraindication includes Arrhythmias (sustained Vtach)
Recent MI or Unstable Angina
Significant LV outflow obstruction
Aortic dissection
Moderate or Severe Hypertension (beware of this simple contraindication, very often test premature terminated due to hypertension).
Adenosine works on A2A receptor causing coronary vasodilation. Areas with plaques do not vasodilate. This creates a difference in blood flow between well-perfused areas and diseased areas, which can be visualized with nuclear imaging.
Regadenosone, binodenoson, apadenoson are selective A2A receptor and less risk of bronchospasm.

8. Imaging Agents Stressor Pro Con EKG Simple, less expensive
Less information. May not be able to localize the lesion. Can not use if there are baseline EKG abnormalities i.e. LBBB with ST changes
Echocardiogram
Good if patient has pre-existing EKG abnormalities. More info than EKG. Less expensive than nuclear.
Operator dependent to some extent. May have poor windows due to body habitus. Pre-existing wall motion abnormalities may make interpretation more challenging.
Thallium or technetium
Localizes ischemia and infarcted tissue.
Expensive
Slide courtesy of Dr. Varaz Bozoghlanian (Chief Resident )

9. Finally … What is a “MIBI?” What is a “Lexiscan?”
Both are adenosine nuclear stress tests
MIBI: the technetium molecule is attached to sestamibi molecule. The combined sestamibi-Technitium-99 molecule is aka “cardiolite”
Lexiscan: uses a derivative of adenosine called regadenosine, which has 2-3 minute half-life instead of 30sec, so is easier to work with.

10. Sensitivity and Specificity
Exercise EKG
68%
77%
Stress Echo
76%
88%
Nuclear Imaging
79-92%
73-88%
Keep in mind of sensitivity and specificity of each modality.

11. Diagnosis or Prognosis
Selecting Modalities
Indication
Diagnosis or Prognosis
Localize Ischemia
Exercise?
Exercise? no no
yes
Pharmacologic test
with Imaging
yes
Finally …
Normal EKG
Not on Digoxin
No prior revascularization no
Exercise Imaging
yes
Exercise EKG

12. Case Question
A 60yo man is evaluated for chest pain of 4 months’ duration. He describes the pain as sharp, located in the left chest, with no radiation or associated symptoms, that occurred with walking one to two blocks and resolves with rest. Occasionally, the pain improves with continued walking or occurs during the evening hours. He has hypertension. Family history does not include cardiovascular disease in any first-degree relatives. His only medication is amlodipine.
On physical examination, he is afebrile, blood pressure is 130/80mHg, pulse rate is 72/min, and respiration rate is 12/min. BMI is 28. No carotid bruits are present, and a normal S1 and S2 with no murmurs are heard. Lung fields are clear, and distal pulses are normal. EKG showed normal sinus rhythm.

13. Case Question
Which of the following is the most appropriate diagnostic test to perform next?
Adenosine nuclear perfusion stress test.
Coronary angiography
Echocardiography
Exercise treadmill
Answer D
This patient has intermediate risk. His ability to exercise and normal ECG makes answer D the best modality.

14. Take Home Points
Stress testing is indicated for patients with intermediate pre-test probability
Each stress test has two components: an imaging modality and stress modality
When determining which stress test to order, keep in mind their ability to exercise and whether any contraindications are present