Stress TestingWho needs it?Rafat Padaria, M.D.

CVM, P.C.

Stress Testing

Indications for stress test

What are the options?

Description of each

Comparison of various modalities

Noninvasive Testing Options

StressECG

StressEcho

StressMPI

EBCT

PET

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)

Exercise Stress TestProtocols

Bruce Protocol

Modified Bruce

Naughton

Bicycle Protocol

Stress ECG

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.

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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

Stress Echo

Stress Echo

Stress Echo

Stress Echo

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

Normal Study

Computer-rendered, 3-D Image of Left Ventricular Surfaces

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MACINTOSH

WINDOWS

Single Vessel Disease- RCA

2 Vessel Disease LAD & RCA

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%

Cardiac PET Imaging:

PET Scanner

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.

CVM Diagnostic Staff