Stress Testing :
Which Test to Choose?
Gary J. Balady, MD
Professor of Medicine
Boston University School of Medicine
Stress Testing at
Boston Medical Center
•
•
•
•
•
•
Exercise ECG ( treadmill test)
Exercise – Echo
Exercise – Nuclear
Cardiopulmonary ( Metabolic )
Dobutamine –Echo
Pharmacologic (regadenoson) nuclear
– SPECT
– PET
• SCM Order Set: stress test selector
supply
demand
supply
coronary arteries
• atherosclerosis
• coronary vasospasm
• hypoxemia
• anemia
• hypotension
• coronary anomalies
• coronary vasculitis
demand
factors
• HR x BP
• contractility
• wall stress
Supply
• Degree of obstruction
• Length of lesion
• Dynamic properties of lesion
•Dynamic properties of
distal vascular bed
• thickness of myocardium
Supply
Collateral flow
supply
demand
factors
• HR x BP
• contractility
History
• Chest discomfort
– Types of angina
• Quality of discomfort/location
• Provocative factors
• Relief
• Age/Gender/Risk Factors
• Classes of Angina
Physical Examination
• hypertension
• weight/body habitus
• vascular bruits
• heart size
• skin
• eye grounds
Resting Electrocardiogram
Exercise Testing Protocols
Work = force x distance
Workrate = work/time
VO2 is directly related to workrate
Treadmill
• Force = body weight
• Distance/time=
Treadmill speed
• Estimated VO2
(ml/kg/min)
– ACSM regression
equations
– METs
Stationary Cycle
• Force = resistance
against the flywheel
• Distance/time=
Cycling speed
• Estimated VO2 (ml/min)
– ACSM regression
equations
– Need body weight to
calculate METs
METs
Stepped
METs
Ramp
Time 
10 min
Bruce Protocol for Treadmill Testing
STAGE
TIME
SPEED (mph)
GRADE (%)
METS
REST
00.00
0.0
0.0
1.0
1
03.00
1.7
10.0
4.6
2
03.00
2.5
12.0
7.0
3
03.00
3.4
14.0
10.1
4
03.00
4.2
16.0
12.9
5
03.00
5.0
18.0
15.1
6
03.00
5.5
20.0
16.9
7
03.00
6.8
22.0
19.2
Boston Medical Center Ramp Protocols
Stage*
Very Low Ramp
mph
Low Ramp
Moderate Ramp
High Ramp
Athlete’s Ramp
% grade
METs
mph
% grade
METs
mph
% grade
METs
mph
% grade
METs
mph
% grade
METs
1
1.0
0.0
1.8
1.0
0.0
1.8
1.5
1.5
2.5
2.1
3.0
3.5
1.8
0.0
2.4
2
1.1
0.2
1.9
1.1
0.5
1.9
1.6
2.0
2.7
2.2
4.0
3.9
2.1
0.5
2.7
3
1.2
0.4
2.0
1.2
1.0
2.1
1.7
2.5
2.9
2.3
4.5
4.2
2.4
1.0
3.2
4
1.3
0.6
2.1
1.3
1.5
2.3
1.8
3.0
3.1
2.4
5.5
4.6
2.7
1.5
3.6
5
1.4
0.8
2.2
1.4
2.0
2.5
1.9
3.5
3.4
2.5
6.0
5.0
3.3
2.0
4.1
6
1.5
1.0
2.3
1.5
2.5
2.7
2.0
4.0
3.6
2.6
7.0
5.5
3.3
2.5
4.6
7
1.6
1.2
2.5
1.6
3.0
2.9
2.1
4.5
3.9
2.7
7.5
5.8
3.6
3.0
5.2
8
1.7
1.4
2.6
1.7
3.5
3.1
2.2
5.0
4.2
2.8
8.5
6.4
3.9
3.5
6.1
9
1.8
1.6
2.8
1.8
4.0
3.4
2.3
5.5
4.5
2.9
9.0
6.8
4.2
4.0
7.3
10
1.9
1.8
2.9
1.9
4.5
3.6
2.4
6.0
4.8
3.0
10.0
7.4
4.5
4.5
8.4
11
2.0
2.0
3.1
2.0
5.0
3.9
2.5
6.5
5.1
3.1
10.5
7.8
4.8
5.0
9.5
12
2.1
2.2
3.2
2.1
5.5
4.2
2.6
7.0
5.5
3.2
11.5
8.5
5.1
5.5
10.6
13
2.2
2.4
3.4
2.2
6.0
4.5
2.7
7.5
5.8
3.3
12.0
8.9
5.4
6.0
11.5
14
2.3
2.6
3.6
2.3
6.5
4.8
2.8
8.0
6.2
3.4
13.0
9.7
5.7
6.5
12.2
15
2.4
2.8
3.8
2.4
7.0
5.1
2.9
8.5
6.6
3.5
13.5
10.1
6.0
7.0
13.0
16
2.5
3.0
3.9
2.5
7.5
5.5
3.0
9.0
7.0
3.6
14.5
10.9
6.3
7.5
13.8
17
2.6
3.2
4.1
2.6
8.0
5.8
3.1
9.5
7.4
3.7
15.0
11.4
6.6
8.0
14.7
18
2.7
3.4
4.3
2.7
8.5
6.2
3.2
10.0
7.8
3.8
16.0
12.2
6.9
8.5
15.5
19
2.8
3.6
4.5
2.8
9.0
6.6
3.3
10.5
8.3
3.9
16.5
12.6
7.2
9.0
16.4
20
2.9
3.8
4.7
2.9
9.5
7.0
3.4
11.0
8.7
4.0
17.5
13.3
7.5
9.5
17.3
Duke Activity Status Index
Diagnostic level of stress: 85% maximum predicted HR
where MPHR = (220-age)
Normal Response
Ischemic
Response
Sensitivity/Specificity/Predictive Value
high prevalence population
Positive
Test
Negative
Test
Total N
CAD
No CAD
63
3
95
27
7
21
90
10
Predictive
Value
exercise ecg test: 70% sensitive/ 70% specific
Sensitivity/Specificity/Predictive Value
low prevalence population
Positive
Test
Negative
Test
Total N
CAD
No CAD
7
27
21
3
63
95
10
90
Predictive
Value
exercise ecg test: 70% sensitive/ 70% specific
Duke Prognostic Scoring System
x
x
x
*
x
Heart Rate Recovery
Heart Rate Recovery:
Risk of mortality at 6 years
Cole, et al. NEJM 1999: 341:1351
Cleveland Clinic ETT Score
Lauer, et al. Ann Int Med 147:821-828; 2007
Hypertension During Exercise:
BPs > 180 at 7 METs
Circulation 2010: 121: 2109
Oxygen Uptake - Workrate relationship
VO2 
No handrail
?
Workrate 
Handrail
CPX System
•
•
•
•
Oxygen sensor
Carbon dioxide sensor
Volume measures/flow meters
Breath by breath measures
– BTPS
– Expired air
• Oxygen uptake
• Carbon Dioxide production
• Ventilation
Indications for CPX
• Accurate assessment of exercise capacity
– Clinical
– Research
• Diagnosis
– Dyspnea on exertion
• Prognosis
– Heart failure
– Congenital Heart Disease
• Disability assessment
• Treatment
– Pacemaker settings
Exercise Testing
additional indications
• Adequacy of therapy
– medical
– revascularization ( imaging tests)
• Activity counseling
– MET Chart
• Exercise prescription
• Rhythm assessment
• Valvular Heart Disease
–
–
–
–
Aortic stenosis
Mitral stenosis
Mitral regurgitation
Hypertrophic obstructive cardiomyopathy
Exercise Prescription
Patients with CHD
• Intensity
– Exercise Test
• calculate heart rate reserve (HRR)
– peak HR minus resting HR
– moderate intensity:
» 50% HRR plus resting HR to
» 70% HRR plus resting HR
» keep peak peak HR 10 beats < HR
at ischemia
– Risk Stratify using AHA criteria
Stress Imaging Tests
•Abnormal resting ECG
•ST segments
•Left bundle branch block
•LVH with strain
•Need for increased
diagnostic accuracy
sensitivity 85-90%
specificity 85-90%
•localize ischemia to
specific coronary vascular territory
Contrast Echo
Stress Echocardiogram: Apical septal wall ischemia
Stress Nuclear Testing
tomographic imaging planes
Short Axis
•base to apex
Vertical Long Axis
•septal to lateral
Horizontal Long Axis
•anterior to inferior
normal nuclear perfusion scan
stress
rest
stress
rest
stress
rest
lateral ischemia on nuclear perfusion scan
stress
rest
stress
rest
stress
rest
Pharmacological Stress Tests
dobutamine echo
Dobutamine
• beta agonist
• increases myocardial oxygen demand
• increases HR, BP, contractility
Pharmacological Stress Tests
nuclear perfusion scan
Adenosine or Dipyridimole
• direct coronary vasodilator
• causes shifts in flow leading to
relative reduction in flow distal to
coronary stenosis
• minimal change in HR, BP, and
contractility
Myocardial Perfusion Imaging:
Pharmacologic Positron Emission Tomography (PET) vs.
Single Photon Emission Computed Tomography (SPECT)
PET
•
•
•
•
•
Energy: 511 KeV
Resolution: 1.5 cm
Protocol: 45 min
Stress EF
Myocardial flow
quantification
• More expensive than
SPECT
SPECT
•
•
•
•
Energy: 80-140 KeV
Resolution: 2.0 cm
Protocol: 2-3 h ( or 2 d)
Post-Stress EF
Courtesy of Edward Miller, MD, PhD
For more information
• www.americanheart.org
–Scientific publications
•Statements and guidelines
–Exercise standards -2013
Elective in Stress Testing
•
•
•
•
Second and third year residents
3 weeks – preferably continuous
Fellow surrogate
Certification in Exercise-ECG Testing
– Supervision and interpretation
• Exposure to stress echo and stress
nuclear
Approximate METs during Stationary Cycle Testing
Exercise rate (kg · m · min-1 and watts)
Body weight
kg
Lb
Kpms
300
Watts
50
450
600
750
900
1050
1200
75
100
125
150
175
200
50
110
5.1
6.9
8.6
10.3
12.0
13.7
15.4
60
132
4.3
5.7
7.1
8.6
10.0
11.4
12.9
70
154
3.7
4.9
6.1
7.3
8.6
9.8
11.0
80
176
3.2
4.3
5.4
6.4
7.5
8.6
9.6
90
198
2.9
3.8
4.8
5.7
6.7
7.6
8.6
100
220
2.6
3.4
4.3
5.1
6.0
6.9
7.7
Myocardial Contractility
Myocardial Wall Stress
R
P
Th
Wall stress =
P x R/ Th