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Stress Testing
Indications for stress test
What are the options?
Description of each
Comparison of various modalities
Noninvasive Testing Stress
ECG
• Several protocols available
• General goal is achievement of 85% of MPHR
• Ischemia defined by ST-segment depression
• Other hemodynamic parameters monitored
Courtesy of Howard Lewin, MD, of San Vicente Cardiac Imaging Center.
Indications:
Class I:
• Adults with intermediate CAD risk & symptoms
• Initial workup of suspected or known CAD
• Known CAD with change in clinical status
• Submaximal EST, 4-7 days post-MI followed by symptom-limited EST at 3-6 weeks
• Symptom limited EST at 14-21 days post-MI
Indications:
Class IIa: • Patients with vasospastic angina
• For post-discharge rehab after PTCA or CABG
• Evaluation of known or suspected exercise related arrhythmia, pre or post ablation.
Indications:
Class IIb: • Patients with high or low probability of
CAD
• On digoxin with ≤ 1mm ST segment depression
• LVH by EKG with ≤ 1mm ST segment depression
Indications:
Class III: • Severe comorbidity obviating
revascularization.
• EKG changes preventing interpretation of the test.
STRESS TESTING: ABSOLUTE CONTRAINDICATION
Patient with acute MI
Patient with acute myocarditis or pericarditis
Patient with unstable progressive angina
Patient with rapid ventricular and atrial arrhythmias
Patient with 2nd and 3rd degree AV block
Acutely ill patient i.e. with infection, hyperthyroidism or severe anemia
STRESS TESTING:RELATIVE CONTRAINDICATION
Aortic stenosis
Hi-grade LVOT
Suspected left main equivalent
Severe hypertension 240/130
Severe ST depression at rest and history of angina
Congestive heart failure – rales, edema
AAA (adenosine most forgiving type of stress test)
High Risk IndicatorsExercise Stress Testing
Early positive-stage I: Mortality >5%/yearStrongly positive > 2.5 mm ST depressionST elevation > 1 mm in leads without Q wavesFall in SBP >10 mm HGEarly onset ventricular arrhythmia'sChronotropic incompetence Ex HR <120/min not due to drugsProlonged Ischemic changes in recovery> 2mm lasting > 6 minutes in multiple leads
Non invasive Imaging
• Requires adequate exercise capacity
• Is non diagnostic in:– LBBB– Digoxin/β-blockers– Baseline ST abnormalities– Left ventricular hypertrophy
Advantages Disadvantages
• Available in many physician offices
• Relatively inexpensive• Provides hemodynamic
information• Can detect arrhythmias
Stress
ECG
• Ultrasound performed both at rest and during peak stress
• Stress–exercise or pharmacologic
• Ischemia defined by development of wall motion abnormalities
Stress
Echo
Courtesy of Howard Lewin, MD, of San Vicente Cardiac Imaging Center.
IF YOU DON’T SEE ANIMATION, CLICK A LINK BELOW:
MACINTOSHWINDOWS
Stress Echo: Exercise or Dobutamine
Indicated to increase sensitivity and specificity of stress testing
Pharmacologic stress-usually dobutamine if exercise not possible
Indicated in women with intermediate probability CAD, LBBB, LVH, resting ST changes
Dobutamine Stress Echo
Positive inotrope and chronotrope
Induces ischemia via increased HR, BP & contractility
Preferred agent if Persantine or aggrenox on board history of asthma or COPD
Critical carotid stenosis
Dobutamine Echo:Contraindications
Ventricular arrhythmias
Recent myocardial infarction (one to three days)
Unstable angina
Hemodynamicaly significant left ventricular outflow tract obstruction
Severe aortic stenosis
Aortic aneurysm or aortic dissection
Systemic hypertension
Noninvasive Testing Options
• Operator dependent
• Image quality suboptimal in significant number of patients
• Ischemic wall motion abnormalities do not persist after exercise termination
• Available in many cardiology offices
• Allows evaluation of valvular function and myocardial morphology
Advantages Disadvantages
Stress
Echo
Noninvasive Testing Options
• Stress–exercise or pharmacologic vs rest
• Myocardial accumulation of radioactivity in proportion to blood flow
• Ischemia defined by diminished perfusion duringstress vs rest
Stress
MPI
Courtesy of Howard Lewin, MD, of San Vicente Cardiac Imaging Center.
Stress Mibi
Rest Mibi
Stress Mibi
Rest Mibi
Stress Mibi
Stress Mibi
Rest Mibi
Rest Mibi
Indications for Myocardial Perfusion Imaging (Exercise or Pharmacologic Stress)
Suspected false +ve or-ve TMT
Resting ST changes
LBBB,RBBB,LVH, digitalis, pre-excitation or pacemaker
Women with +ve TMT and low or intermediate probability CAD
Inability to exercise
Prognosis of known CAD
Detecting post PTCA or CABG ischemia
Assessing myocardial viability
Risk evaluation in non-cardiac surgery patients
Assessment functional significance of documented coronary stenosis
SPECT MPI
Exercise Stress
Treadmill
Bicycle ergometer
Pharmacologic Stress
Regadenoson
Dobutamine
Isotopes
Thallium 201
Technetium 99m
Sestamibi MIBI (Cardiolyte)
Tetrofosmin (Myoview)
Regadenoson Stress TestRegadenoson is an A2A adenosine receptor agonist that is a coronary vasodilator
The maximal plasma concentration of Regadenoson is achieved within 1 to 4 minutes after injection
Recommended dose is 0.4 mg given as rapid bolus
Contraindications
1) Patients with second- or third-degree AV block or sinus node dysfunction without a functioning pacemaker
2) Known hypersensitivity to adenosine or regadenoson
3) Systolic blood pressure less than 90mmHg
4) Reactive airways disease.
5) Profound sinus bradycardia (heart rate < 40 beats/minute
Noninvasive Testing Options
• Ionizing radiation required
• Attenuation artifacts in small percentage of patients
• Time required for imaging
• Operator independent
• Reproducibly good image quality
• Gating allows acquisition of LV volumes
• Simultaneous perfusion and function assessment
• Able to assess myocardial viability
Advantages Disadvantages
Stress
MPI
Computer-rendered, 3-D Image of Left Ventricular Surfaces
IF YOU DON’T SEE ANIMATION, CLICK A LINK BELOW:
MACINTOSH
WINDOWS
Noninvasive Testing Options
• Resting study only
• Stationary tungsten target permits rapid scanning
• Detects coronary calcification
• Abnormality defined as presence of any calcium
EBCT
Courtesy of Howard Lewin, MD, of San Vicente Cardiac Imaging Center.
Noninvasive Testing Options
• Unable to evaluate ischemia; anatomic data only
• Unable to evaluate myocardial function
• Limited prognostic data
• Insurance coverage rare
• Stress not required
• Relatively low cost
• Rapid testing –10 minutes
Advantages Disadvantages
EBCT
Noninvasive Testing Options
• Rest and pharmacologic stress
• Images radioactive tracers of flow and metabolism
• Ischemia defined as difference in regional blood flow during pharmacologic stress
PET
Courtesy of Howard Lewin, MD, of San Vicente Cardiac Imaging Center.
Noninvasive Testing Options
• Very limited availability
• High cost
• On-site cyclotron may be required
• No ECG or hemodynamic data available from exercise
• Good image quality
• Faster study
• Less radiation
• Allows quantification of myocardial blood flow
• Gold standard for viability assessment
Advantages Disadvantages
PET
Persantine (dipyridamole)
Coronary vasodilatorWith coronary stenosis differential dilatation results in differential flow hence differential uptake of isotopeSide effects
Chest pain 20%Dizziness12%Headache 12%Dyspnea & flushing 5%
Comparing SPECT and PET
Examples of improved diagnostic reliability of PET vs. SPECT MPI in the same patients. (A) A 70-y-old man status post CABG with no history of MI. Exercise/rest SPECT images are normal but left ventricular ejection fraction was surprisingly reduced at 0.39. PET MPI within 2 wk discloses a clinically occult posterobasal MI. (B) A 53-y-old man with exertional left arm pain. SPECT images with dipyridamole stress are normal. PET MPI within 2 wk demonstrates a reversible inferoseptal perfusion defect. Ninety percent circumflex stenosis found on coronary arteriography. (C) A 46-y-old woman with chest pain. SPECT images are equivocal for reversible ischemia in inferolateral wall. PET images are normal. (D) A 59-y-old woman with chest pain. SPECT images are equivocal for reversible inferolateral ischemia as in C. PET images demonstrate reversible inferoseptal perfusion defect, treated with PTCI of 95% dominant right coronary artery stenosis
Pearls
If for evaluation of CP and patient can walk and no baseline ECG changes : ETT
If for prognosis : Exercise MPI/ Regadenoson MPI or Cardiac PET MPI if functionally limited
Stress Echo excellent choice in women for diagnosis of CAD, has a high Negative Predictive Value
PET MPI: expensive but very accurate and specific, less radiation exposure to patient.