Stress tests use physical or pharmacological stress to detect coronary artery disease. Exercise treadmill testing is commonly used but has limitations. Myocardial perfusion imaging and stress echocardiography can detect ischemia through abnormal perfusion or wall motion changes during stress. The choice of stress test depends on the patient's clinical characteristics and contraindications to certain stress modalities.

1. Stress Testing
UTSW House Staff Didactic Series
Anand Rohatgi, MD, MSCS, FACC, FAHA
Assistant Professor
Division of Cardiology

2. Stress Tests
Stress modality “Detection” modality
Treadmill exercise*
Vasodilator
Adenosine
Regadenson
Dobutamine
EKG (ETT)
Myocardial perfusion
Echo (stress echo)

3. Probability
Gibons at al, Progr Cardiol 1983;12:67
Positive Predictive
Value
Probability of a subject
with a positive test,
actually having disease
Depends upon
Sensitivity
Specificity
Population prevalence
or pretest likelihood

4. Pretest Probability
Age Gender Typical
Angina
Atypical
Angina
Nonanginal
CP
Asymptoma
tic
30-39 Men Intermediate Intermediate Low Very Low
40-49 High Intermediate Intermediate Low
50-59 High Intermediate Intermediate Low
60-69 High Intermediate Intermediate Low
30-39 Women Intermediate Very Low Very Low Very Low
40-49 Intermediate Low Very Low Very Low
50-59 Intermediate Intermediate Low Very Low
60-69 High Intermediate Intermediate Low
Diamond et al, NEJM 1979;300:1350

5. ACC/AHA 2002 ETT Indication
Class I (Indicated)
• Intermediate prob
CAD
• including RBBB,
<1mm resting ST
depression
Class III (Not indicated)
• Pre-excitation
• V-paced
• >1mm resting ST dep
• LBBB
• Diagnosis for pt w/
established CAD
MI or death 1 per 2500

6. Contraindications to ETT
• Acute myocardial infarction (<2 days)
• Unstable angina with recent rest pain
• Untreated life-threatening cardiac arrhythmias
• Advanced atrioventricular block
• Acute myocarditis or pericarditis
• Critical aortic stenosis or severe IHSS
• Uncontrolled hypertension
• Acute systemic illness (PE, dissection, anemia,
thyroid, fever, etc.)

7. Exercise Treadmill Testing- Protocols
Standard Bruce Protocol
Stage Min MPH Grade METS
I 03:00 1.7 10% 5
II 03:00 2.5 12% 7
III 03:00 3.4 14% 10
IV 03:00 4.2 16% 13.5
V 03:00 5.0 18% 16+
*3 minute stages
Variations
Modified Bruce Protocol
2 warm-up stages
Naughton Protocol
fixed speed
Submaximal ETT
Not to exceed 5 METS
Not to exceed 70%
MPHR

8. Diagnosis of Ischemia
Positive test
– 1mm horizontal or
down sloping ST
segment depression
0.06-0.08msec after
the j-point
(5% w/ CAD meet
criteria in recovery
alone)
– Lateral leads (V4-V6)
Up sloping
Horizontal
Down sloping
Adequate stress: 85% max predicted HR (220-age)

9. Decreased Specificity
• LVH with repolarization abnormalities
– Decreased specificity with no change in sensitivity
• Resting ST depression > 1mm
• LBBB
• RBBB (diagnostic accuracy preserved in V5, V6, II, AVF
• Digoxin
– ST depression in 25-40% of healthy subjects
– 2 weeks required washout

10. Non-coronary Causes of ST
segment depression
• Severe aortic stenosis
• Severe hypertension
• Cardiomyopathy
• Anemia
• Hypokalemia
• Severe hypoxia
• Digitalis use
• Sudden excessive
exercise
• Glucose load
• Left ventricular
hypertrophy
• Hyperventilation
• Mitral valve prolapse
• Intraventricular
conduction defect
• Preexcitation syndrome
• Severe volume overload
• Supraventricular
tachyarrhythmias

12. Thompson CA, et al. JACC 2000; 36:2140-5. Lauer MS, et al. Circulation 1996;93:1520-6

13. Prognostic Markers
• Maximal exercise capacity
• Chronotropic incompetence
• HR recovery
• Risk scores

14. Exercise Capacity
MET= 02 uptake of 70kg
man at rest for 1 min
=3.5ml O2/kg/min
Exercise capacity is
one of the strongest
prognostic markers
Encompasses many
different factors
Each 1 MET increase =
12% increased
survival
Stanford database of 6000 men
>13 >11
Ref
<10 <8
Myers et al, NEJM 2002;346:793

15. ETT in asymptomatic pts
Class I
• None.
Class IIa
• Evaluation of asymptomatic persons with diabetes mellitus who plan to start
vigorous exercise (see page 39). (Level of Evidence: C)
Class IIb
• Evaluation of persons with multiple risk factors as a guide to risk-reduction therapy.*
• Evaluation of asymptomatic men older than 45 years and women older than 55
years:
– Who plan to start vigorous exercise (especially if sedentary) or
– Who are involved in occupations in which impairment might impact public safety or
– Who are at high risk for CAD due to other diseases (e.g., peripheral vascular disease and
chronic renal failure)
Class III
• Routine screening of asymptomatic men or women.

16. Myocardial Perfusion Imaging
Stress modality “Detection” modality
Treadmill exercise*
Vasodilator
Adenosine
Regadenson
Dobutamine
Myocardial perfusion
(Nuclear)

17. Myocardial Perfusion Imaging
Schinkel AF, Bax JJ, Geleijnse ML, et al. Eur Heart J 2003;24:789-800.

18. Myocardial Perfusion Testing
Maximal coronary
vasodilitation
Rest
No coronary flow
reserve
Stress
Heterogeneous
Perfusion

19. Vasodilators
• Dipyridamole
– Increases adenosine levels
– 50% with side effects, last 15-25 minutes
• Adenosine
– Coronary vasodilation via A2A receptor
– 140mcg/kg/min x 6min
– 80% with side effects: flushing 40%, AV block
(7.6%), hypotension (5%), <10sec ½ life
– CP non-specific
– 1mmST depression 5-7%>CAD
• Regadenoson
– A2A agonist with lower affinity for receptors >
side effects
– Side effets of SOB, headache, flushing, last 15-
30 min
– Single 5ml injection
Contra-indications
• AV block (2nd or 3rd)
•Bronchospasm
•Methyl xanthines
•ACS

20. Myocardial Perfusion Testing
(Nuclear: SPECT)
Protocol (Dual Isotope)
• Resting images after Thallium-201
injection
• Stress, with Technetium-99 injected at
peak exercise (Cardiolite/Myoview)
• Post-stress images (with gated SPECT)

21. → Revasc better
Hachamovitch R, Hayes SW, Friedman JD, Cohen I, Berman DS. Circulation 2003;107:2900-6

22. Stress Tests
Stress modality “Imaging” modality
Treadmill exercise*
Vasodilator
Adenosine
Regadenson
Dobutamine Echo (stress echo)

23. Stress Echo
Schinkel AF, Bax JJ, Geleijnse ML, et al. Eur Heart J 2003;24:789-800.
Abnormal
flow reserve
Ischemia

24. Stress Echocardiography
• Stress echo is used to
assess ischemia
• Wall motion
abnormalities are the
earliest response to
ischemia
Post-balloon inflation
19
30
39
0 50
Chest
Pain
EKG
change
Wall
Motion
Seconds
Hauser et al. JACC
1985;5:193

25. Dobutamine Echo
Mechanisms of Action
– β1 agonist– inotropy and
chronotropy (some
vasodilatation)
– induces ischemia at lower
RPP than ETT, (RPP
approximately 16-20K)
– Begin at 10mcg/kg/min,
increasing to 40 mcg/kgmin
Side Effects
– 3:1000 serious side effects
• MI
• Ventricular fibrillation
– Atrial / Ventricular
arrhythmia
– Hypertension
– Hypotension (cavity
obliteration)
– Headache / Tremor

26. Comparing SECHO and MPI
Advantages Disadvantages
MPI (Nuclear)
Detects abnl flow reserve
Peak-exercise images
acquired
Most studies complete
Quantified LVEF and
volumes
Longer time than secho
Radiation
Lower spatial resolution
Inferior wall diff to eval
Balanced ischemia missed
SECHO
Safe
No radiation
Portable, faster
Structural information
Peak-exercise images
difficult to acquire
False-neg w/ rapid recovery
Ischemic response needed
15% cannot assess entire
myocardium
Afib, LBBB

27. ETT
EKG not
interpretable
Stress
Echo
Poor echo
arrhythmia
Stress
MPI
Asthma
COPD
AV Block
Dobutamine
Echo
LBBB
V-paced
arrhythmia
Poor echo
Adenosine
MPI
Unable
to walk
Poor echo
Dobutamine
MPI