STRESS TESTING
Indications, modalities
and patient selection
Miguel A. Leal, M.D.
Fellow, Cardiovascular Medicine
University of Wisconsin
February - 2008
Disclosures
None whatsoever!
Stress Testing
When? – Indications
What type? – Modalities
Who? – Patient selection
How often? – Frequency
How much? – Cost
Diagnostic Testing
• Testing threshold
• Diagnostic uncertainty
• Treating threshold
The 2 x 2 (or 4 x 4) table
Test
Disease
Positive
Negative
Present
A
C
Se
A/(A+C)
Absent
B
D
Sp
D/(B+D)
PPV
A/(A+B)
NPV
D/(C+D)
Acc
(A+D)/total
How “normal” is the normal curve?
The norm isn’t always the norm…
Which test is more accurate?
• An exercise treadmill test (Se 80%, Sp 90%)
in a population of post-CABG patients with
worsening angina?
or
• The same test (Se 80%, Sp 90%) in a
population of young, healthy women without
family history of CAD?
Statistics can be tricky…
1
+
P 40%
1000
CAD
320
-
No
CAD
540
80
Accuracy
60
86%
2
P 5%
1000
CAD
+
-
40
95
No
CAD
10
855
vs.
89.5%
If there is one thing
you should think about
before ordering ANY test…
LIKELIHOOD RATIO
Stress Testing: Who?
Adults with intermediate (10-90%)
pre-test probability of CAD
Age
30-39
40-49
50-59
60-69
Sex
Typical
Atypical
Non-anginal
Asymp
Male
Intermediate
Intermediate
Low
Very low
Female Intermediate
Very Low
Very low
Very low
Male
Intermediate
Intermediate
Low
Female Intermediate
Low
Very low
Very low
Male
Intermediate
Intermediate
Low
Female Intermediate
Intermediate
Low
Very low
Male
High
Intermediate
Intermediate
Low
Female High
Intermediate
Intermediate Low
High
High
Angina
Precordial (retrosternal) chest pain that…
•
•
•
Is triggered by physical or emotional stress
Is relieved by rest or SL NTG
Lasts for 15-20 minutes each episode
For those of you who like history…
First described in 1772 by the English physician
William Heberden in 20 patients who suffered from
"a painful and most disagreeable sensation in the
breast, which seems as if it would extinguish life, if it
were to increase or to continue." Such patients, he
wrote, "are seized while they are walking (more
especially if it be uphill, and soon after eating). But
the moment they stand still, all this uneasiness
vanishes."
Sir William Heberden, 1710-1801
Back to contemporary times…
Classic anginal features:
•
•
•
Is triggered by physical or emotional stress
Is relieved by rest or SL NTG
Lasts for 15-20 minutes each episode
2-3/3: typical angina
1/3: atypical angina
0/3: likely non-cardiac chest pain
Importance of typicality
7
6
5
4
3
Mortality
2
1
0
Typical
Atypical
Noncardiac
560 patients presenting for exercise tolerance testing (treadmill)
Prospective follow-up over 5.8 years
Jones et al. Prognostic importance of presenting symptoms in patients undergoing exercise testing for evaluation
of known or suspected coronary disease. Am J Med 2004.
Stress Testing: Who?
• Patients with symptoms or prior history of CAD
– Initial evaluation with suspected or known CAD
– Known CAD with change in status (crescendo)
– Low risk, unstable angina 8-12 hours after
presentation free of symptoms (“rule out time”)
– Intermediate risk, unstable angina, 2-3 days
free of active ischemia
Stress Testing: Who?
• Post-MI
– Prognostic assessment
– Activity prescription
– Evaluation of medical therapy
– Before beginning cardiac rehabilitation
Stress Testing: Who?
• Special Groups
– Women
• Lower sensitivity, similar specificity
– Elderly (>75 years of age)
• Other evaluated endpoints include chronotropic
response, exercise-induced arrhythmias, and
assessment of exercise capacity
Chronotropic response
Stress Testing: Who?
• Asymptomatic patients
– Diabetics planning to start exercise
– Guide to risk reduction therapy in a patient
with multiple risk factors*
– Men > 45 and women > 55
• Starting exercise
• Impact public safety
• High risk due to concomitant disease (PVD, CRF)
Stress Testing:
Absolutely Who Not!
•
•
•
•
•
•
•
•
Acute MI
High risk unstable angina
Uncontrolled arrhythmias with symptoms
Symptomatic, severe aortic stenosis*
Uncontrolled, symptomatic heart failure
Acute PE
Acute myocarditis or pericarditis
Acute aortic dissection
Stress Testing:
Maybe Who Not?*
•
•
•
•
•
•
•
•
Left main coronary stenosis
Moderate stenotic valvular heart disease
Electrolyte abnormalities
Severe hypertension (SBP > 200, DBP > 110)
Tachy or bradyarrhythmias
Outflow tract obstruction (HCM)
Mental or physical impairment (unsafe)
High-degree AV block
Stress Testing: When?
• Patients with chest pain
– Change in clinical status
• Acute coronary syndromes
– Low, intermediate, high risk (H&P, ECG,
markers – TIMI risk score)
– Low: 8-12 h symptom-free
– Intermediate: 2-3 days symptom-free*
– High: consider chemical imaging study versus
coronary angiography*
Stress Testing: When?
• Post-MI
– Pre-discharge*
• Submaximal (<70% MPHR)
– Early after discharge* (14-21 days)
• Symptom limited (85% MPHR)
– Late after discharge* (3-6 weeks if early test
was submaximal)
• Symptom limited (85% MPHR)
Stress Testing: When?
• Before and after revascularization*
– Demonstration of ischemia
– Evaluation of post-procedure chest pain
– Evaluation of territory at risk
– Evaluation of restenosis
– Post-bypass surgery – useful later not early
Stress Testing: How Often?
• Change in clinical symptom pattern
• Prognostication:
– There is no absolute guarantee
• Progression of testing modality to higher
sensitivity and specificity
• Depends on risk factors, their degree of
control and intensity of modification
Stress Testing: What Type?
• Exercise modality
– Treadmill
• Bruce, Modified Bruce, Branching, Naughton…
– Bicycle (recumbent)
– Chemical/Pharmacologic
• Dipyridamole (Persantine®)
• Adenosine (Adenoscan®)
• Dobutamine
The Bruce protocol
• Developed in 1949 by
Robert A. Bruce,
considered the “father of
exercise physiology”.
• Published as a
standardized protocol in
1963.
• Remains the goldstandard for detection of
myocardial ischemia when
risk stratification is
necessary.
Protocol description
Stage
Time (min)
km/hr
Slope
1
0
2.74
10%
2
3
4.02
12%
3
6
5.47
14%
4
9
6.76
16%
5
12
8.05
18%
6
15
8.85
20%
7
18
9.65
22%
8
21
10.46
24%
9
24
11.26
26%
10
27
12.07
28%
Stress Testing: What Type?
• Non-imaging versus imaging
– Consideration of imaging
•
•
•
•
Resting ST depression (<1 mm)
Digoxin
LVH
Women
Stress Testing: What Type?
• Non-imaging vs. Imaging
– Require imaging
•
•
•
•
•
•
•
Intermediate risk non-imaging exercise test
Pre-excitation
Paced rhythm
LBBB or QRS > 120 ms
> 1 mm resting ST depression
Vessel localization
Improved prognostic information
Stress Testing: What Type?
“To nuke or not to nuke?”
Modality
Exercise test
Nuclear
Imaging
Stress
Echo
Sensitivity
Specificity
68%
77%
87-92%
80-85%
80-85%
88-95%
Normal Myocardial Perfusion
Myocardial Ischemia
Myocardial Infarction
Stress Testing: What Type?
• Choice of imaging modality is multi-factorial
– Body habitus – attenuation, COPD, etc.
– Local expertise
– Claustrophobia
– Understanding of sensitivity and specificity
– Coincident information:
• Ejection fraction
• Valvular structure
• Exercise capacity
Exercise Testing: Contraindications
• Unstable Angina
• Decompensated CHF
• Uncontrolled hypertension (blood pressure
> 200/115 mmHg)
• Acute myocardial infarction within last 2 to
3 days
• Severe pulmonary hypertension
• Relative contraindications (AS, HCM…)
Last but not least… cost
TEST
COST
ETT
$ 140
Comprehensive and well-obtained
History
& Physical Exam:
priceless
ETT + IMAGING
$ 906 (Nuclear)
$ 886 (Echo)
CORONARY
ANGIOGRAPHY
$ 5200
Marine et al. COST-EFFECTIVENESS OF STRESS-ECHOCARDIOGRAPHY.
Cardiology Clinics, Volume 17, 2003.
Stress Testing
• Additional information & references:
– JACC, October 16,2002
– Circulation, October 1, 2002
– www.acc.org
– www.americanheart.org
Thank you!