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Stress Testing :Stress Testing :Which Test to Choose?Which Test to Choose?
Gary J. Balady, MD
Professor of Medicine
Boston University School of Medicine
Stress Testing at Stress Testing at Boston Medical CenterBoston 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 demand
coronary arteries• atherosclerosis• coronary vasospasm• hypoxemia• anemia• hypotension• coronary anomalies• coronary vasculitis
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
Collateral flow
Supply
supply demand
factors• HR x BP• contractility
HistoryHistory
• Chest discomfort– Types of angina
• Quality of discomfort/location
• Provocative factors
• Relief
• Age/Gender/Risk Factors
• Classes of Angina
Physical ExaminationPhysical Examination
• hypertension• weight/body habitus• vascular bruits• heart size• skin• eye grounds
Resting ElectrocardiogramResting Electrocardiogram
Exercise Testing ProtocolsExercise Testing Protocols
Treadmill• Force = body weight• Distance/time=
Treadmill speed
• Estimated VO2 (ml/kg/min)– ACSM regression
equations– METs
Work = force x distanceWorkrate = work/time
VO2 is directly related to workrate
Stationary Cycle• Force = resistance
against the flywheel • Distance/time=
Cycling speed
• Estimated VO2 (ml/min)– ACSM regression
equations– Need body weight to
calculate METs
Time
ME
Ts
ME
Ts
Ramp
Stepped
10 min
Bruce Protocol for Treadmill TestingBruce Protocol for Treadmill Testing
Boston Medical Center Ramp ProtocolsBoston Medical Center Ramp Protocols
Duke Activity Status IndexDuke Activity Status Index
Diagnostic level of stress: 85% maximum predicted HRDiagnostic level of stress: 85% maximum predicted HR where MPHR = (220-age)where MPHR = (220-age)
Normal ResponseNormal Response
IschemicIschemicResponseResponse
Sensitivity/Specificity/Predictive ValueSensitivity/Specificity/Predictive Valuehigh prevalence populationhigh prevalence population
CAD No CAD PredictiveValue
PositiveTest
NegativeTest
Total N 9090 1010
exercise ecg test: 70% sensitive/ 70% exercise ecg test: 70% sensitive/ 70% specificspecific
6363
2727
33
77
9595
2121
Sensitivity/Specificity/Predictive ValueSensitivity/Specificity/Predictive Valuelow prevalence populationlow prevalence population
CAD No CAD PredictiveValue
PositiveTest
NegativeTest
Total N 1010 9090
exercise ecg test: 70% sensitive/ 70% exercise ecg test: 70% sensitive/ 70% specificspecific
77
33
2727
6363
2121
9595
x
x
x
x*
Duke Prognostic Scoring SystemDuke Prognostic Scoring System
Heart Rate RecoveryHeart Rate Recovery
Heart Rate Recovery:Heart Rate Recovery:Risk of mortality at 6 yearsRisk of mortality at 6 years
Cole, et al. NEJM 1999: 341:1351
Cleveland Clinic ETT ScoreCleveland Clinic ETT Score
Lauer, et al. Ann Int Med 147:821-828; 2007
Circulation 2010: 121: 2109
Hypertension During Exercise:Hypertension During Exercise:BPs > 180 at 7 METsBPs > 180 at 7 METs
Oxygen Uptake - Workrate relationshipOxygen Uptake - Workrate relationship
VO
2
Workrate
No handrail Handrail
??
CPX SystemCPX 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 CPXIndications 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 TestingExercise Testingadditional indicationsadditional 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 PrescriptionExercise PrescriptionPatients with CHDPatients 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 TestsStress Imaging Tests
•Abnormal resting ECG•ST segments•Left bundle branch block•LVH with strain
•Need for increaseddiagnostic accuracy
sensitivity 85-90% specificity 85-90%
•localize ischemia to specific coronary vascular territory
Contrast Echo
Stress Echocardiogram: Apical septal wall ischemiaStress Echocardiogram: Apical septal wall ischemia
Stress Nuclear TestingStress Nuclear Testingtomographic imaging planestomographic imaging planes
Short Axis•base to apex
Vertical Long Axis•septal to lateral
Horizontal Long Axis•anterior to inferior
normal nuclear perfusion scan
stress
stress
stress
rest
rest
rest
lateral ischemia on nuclear perfusion scan
stress
stress
stress
rest
rest
rest
Pharmacological Stress TestsPharmacological Stress Testsdobutamine echodobutamine echo
Dobutamine • beta agonist• increases myocardial oxygen demand• increases HR, BP, contractility
Pharmacological Stress TestsPharmacological Stress Testsnuclear perfusion scannuclear 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 informationFor more information
• www.americanheart.org–Scientific publications
•Statements and guidelines–Exercise standards -2013
Elective in Stress TestingElective 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
Body weight Exercise rate (kg · m · min-1 and watts)
kg Lb Kpms 300
Watts 50
450
75
600
100
750
125
900
150
1050
175
1200
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
Approximate METs during Stationary Cycle TestingApproximate METs during Stationary Cycle Testing
Myocardial ContractilityMyocardial Contractility
P ThR
Myocardial Wall StressMyocardial Wall Stress
Wall stress =P x R/ Th