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Cardiac imaging

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; David E. Winchester M.D. M.S.


This chapter presents a brief overview of cardiac imaging techniques. For a detailed discussion of each of the imaging technoloies, please view the chapter on that imaging technology.

Assessment of LV function

Assessment of LV function

Echocardiography

  • Least expensive, most versatile.
  • Portable, immediately available
  • Preferred initial technique to diagnose heart muscle disease of unknown etiology.
  • Regional thickening can be assessed on ECHO and not other techniques and this is a better marker of regional function than is regional wall motion (cant be seen on nuclear or angio studies, MRI can assess though)
  • ECHO is not as good at assessing quantitative ejection fraction (SPECT, angio, RVG are better at this).
  • More sensitive than EKG in diagnosis of LVH.
  • Excellent in estimating LV mass

Radionuclide RVG

  • Good for quantitating LV and RV EFs. Excellent for following the wall motion in patients treated with chemotherapeutic agents.
  • Good for wall motion.
  • In MI does not tell you about infarct expansion, MR, LV thrombus, regional thickening abnormalities.

Gated SPECT Imaging

  • Permits evaluation of regional thickening, global LV function and myocardial perfusion.

Cardiac MRI

  • Good regional and global cardiac function.
  • With contrast agents, good perfusion data
  • Superior for congenital, aortic disease, anomalous coronary arteries, and RV dysplasia
  • Cost benefit ratios of echo and nuclear make them superior for LV function assessment
  • May be best technique for quantitating LV mass
  • As a research tool may be useful in the assessment of LV remodeling

Left Ventriculogram

  • Gold standard in the assessment of wall motion but not in the assessment of wall thickening.
  • LVEF and absolute volumes are highly reproducible
  • LVH and LV mass are better quantitated with echo and MRI
  • Left to right shunts are most accurately quantitated with cardiac cath over echo and MRI
Techniques to Assess CAD and Prognosis

Techniques to Assess CAD and Prognosis

Exercise EKG

  • Strengths
    • Low cost
    • Short duration
    • Functional status evaluation
    • High sensitivity in 3 VD or left main disease
    • Useful prognostic information
  • Limitations
  • Suboptimal sensitivity in the detection of single vessel disease (50%), 85% in the presence of three vessel disease
  • In all patients, overall sensitivity 68%, specificity 77%
  • Beta blocker use is associated with a higher rate of false negatives (fail to achieve rate pressure product)
  • Non diagnostic in patients with abnormal baseline EKG (dig, LVH, WPW)
  • Poor specificity in certain patient populations: premenopausal women, LVH, dig, IVCD, hypokalemia, hyperventilation, severe hypertension, resting ST abnormalities
  • The negative predictive value in women of low to intermediate risk is high, the positive predictive value in men is high
  • Need to achieve > 85% of maximum heart rate for maximizing accuracy
  • Its main values lies in excluding CAD in patients with a low pre test probability of CAD based on gender and age.
Stress Radionuclide Myocardial Perfusion Imaging

Stress Radionuclide Myocardial Perfusion Imaging

  • Strengths
    • Simultaneous evaluation of perfusion and function with gated SPECT
    • Higher sensitivity and specificity than exercise EKG: For exercise or pharmacologic SPECT imaging with Tl or Tc, in patients with chest pain the sensitivity for the detection of CAD is 85% to 90%. Specificity for excluding CAD is in the 90% range. Good in patients with LVH, dig, IVCD etc. ST depression response higher rate pressure product than does a perfusion abnormality with tracers. Therefore they are more sensitive. Adding stress perfusion imaging to the exercise ECG stress test greatly assists in differentiating true positive from false positive ETT ST segment depression. For single vessel disease, the sensitivity is 25% higher with SPECT imaging compared with exercise testing. The sensitivity for detecting 3VD with exercise SPECT is 95% to 100%.
    • High specificity with Tc labeled agents: Half life is shorter than Tl, therefore dose is higher, therefore image is brighter and better. Also allows gated assessment of LV thickening.
    • Studies can be performed in almost all patients
    • Significant additional prognostic information, can quantitate LV function
    • Comparable accuracy with pharmacologic stress testing
    • Viability and ischemia when assessed simultaneously
    • Quantitative image analysis
  • Limitations
    • Suboptimal specificity with thallium imaging, with a high false positive rate in many labs, particularly among women and obese patients.
    • Long procedure time with Tc agents, higher costs than ETT
    • Radiation exposure
    • Poor images in obese patients
    • Pharmacologic stress testing: sensitivity and specificity are similar for persantine and adenosine. Dobutamine is used in those patients with a history of bronchospasm, or for those patients who have consumed coffee before the procedure. Pharmacologic testing is the preferred method in patients with LBBB.
    • Women with chest pain who are referred for exercise or pharmacologic stress testing benefit the most from the enhanced accuracy of Tc imaging. Both Tl and Tc had a sensitivity of about 70%, but the specificity rose to 92% with Tc. Most labs now use Tc because of its improved specificity, the ability to gait the images and assess regional wall thickening. Mild non reversible defects that show preserved systolic thickening usually represent attenuation artifacts, however, if there is abnormal wall thickening, then this is most likely scar.

Template:WikiDoc Cardiology News Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Cardiac radionuclide imaging is a new and rapidly expanding diagnostic modality to the diagnosis and management of heart disease. Clinical applications of cardiac radionuclide imaging include:

Current available modalities are:

Myocardial perfusion imaging (MPI)

  • Stress imaging through:
  • Exercise (treadmill or upright or supine bicycle)
  • Pharmacologic modalities
  • Thallium-201
  • Tc-99m-sestamibi
  • Tc-99m-tetrofosmin
  • Tc-99m-teboroxime (approved for use but not currently marketed in the United States)
  • o Note: Tc-99-m-NOET is currently undergoing multicenter trials and is not yet approved for use.
  • Dual-isotope MPI
  • Gated-planar MPI
  • Gated-single-photon emission computed tomography (SPECT) MPI

Analysis of ventricular function

  • Radionuclide angiography (RNA)
  • First-pass RNA (FPRNA) (Rest, stress)
  • Planar and SPECT-gated equilibrium blood pool RNA (Rest, stress)
  • Procedures for determination of ejection fraction and volumes:
  • FPRNA
  • Gated-equilibrium blood pool RNA
  • Gated-SPECT perfusion imaging

Myocardial infarct-avid imaging

Myocardial ischemia imaging

Positron emission tomography

Major Recommendations

Emergency Department Imaging for Suspected Acute Coronary Syndromes (ACS)

Class I

  • 1. Assessment of myocardial risk in possible ACS patients with nondiagnostic EKG and initial serum markers and enzymes, if available. I (A) [1]
  • 2. Diagnosis of CAD in possible ACS patients with chest pain with nondiagnostic EKG and negative serum markers and enzymes or normal resting scan. I (B) [1]

Class III

  • 1. Routine imaging of patients with myocardial ischemia / necrosis already documented clinically, by ECG and/or serum markers or enzymes III (C) [1]

Use of Radionuclide Testing in Diagnosis, Risk Assessment, Prognosis, and Assessment of Therapy After STEMI

Class I

  • Rest RNA or EGC-gated SPECT for rest LV function in all patients I (B) [1]
  • MPI at rest or with stress using gated SPECT for assessment of infarct size and residual viable myocardium in STEMI patients I (B) [1]
  • Stress MPI with ECG-gated SPECT whenever possible for detection of inducible ischemia and myocardium at risk after thrombolytic therapy without catheterization I (B) [1]

Class IIa

  • Equilibrium or FPRNA for assessment of RV function with suspected RV infarction in STEMI. IIa (B) [1]

Use of Radionuclide Testing for Risk Assessment / Prognosis in Patients with NSTEMI and Unstable Angina

Class I

  • Stress MPI with ECG gating whenever possible for identification of inducible ischemia in the distribution of the “culprit lesion” or in remote areas in patients at intermediate or low risk for major adverse cardiac events. I (B) [1]
  • Stress MPI with ECG gating whenever possible for identification of the severity/extent of inducible ischemia in patients whose angina is satisfactorily stabilized with medical therapy or in whom diagnosis is uncertain. I (A) [1]
  • Stress MPI for identification of hemodynamic significance of coronary stenosis after coronary arteriography. I (B) [1]
  • RNA or gated SPECT for measurement of baseline LV function. I (B) [1]

Class IIa

  • Rest MPI for identification of the severity / extent of disease in patients with ongoing suspected ischemia symptoms when ECG changes are nondiagnostic. IIa (B) [1]

Cardiac Stress Myocardial Perfusion Single-Photon Emission Computed Tomography (SPECT) in Patients Able to Exercise

Recommendations for Diagnosis of Patients With an Intermediate Likelihood of Coronary Artery Disease (CAD) and/or Risk Stratification of Patients With an Intermediate or High Likelihood of CAD Who Are Able to Exercise (to at least 85% of Maximal Predicted Heart Rate)

Class I

  • 1. Exercise myocardial perfusion SPECT to identify the extent, severity, and location of ischemia in patients who do not have left bundle-branch block (LBBB) or an electronically-paced ventricular rhythm but do have a baseline electrocardiogram (ECG) abnormality that interferes with the interpretation of exercise-induced ST-segment changes (ventricular pre-excitation, left ventricular hypertrophy [LVH], digoxin therapy, or more than 1-mm ST depression) (Level of Evidence: B) [1]
  • 2. Adenosine or dipyridamole myocardial perfusion SPECT in patients with LBBB or electronically-paced ventricular rhythm (Level of Evidence: B) [1]
  • 3. Exercise myocardial perfusion SPECT to assess the functional significance of intermediate (25 to 75%) coronary lesions (Level of Evidence: B) [1]
  • 4. Exercise myocardial perfusion SPECT in patients with intermediate Duke treadmill score (Level of Evidence: B) [1]
  • 5. Repeat exercise myocardial perfusion imaging after initial perfusion imaging in patients whose symptoms have changed to redefine the risk for cardiac event (Level of Evidence: C) [1]

Class IIa

  • 1. Exercise myocardial perfusion SPECT at 3 to 5 years after revascularization (either percutaneous coronary intervention [PCI] or coronary artery bypass graft surgery [CABG]) in selected high-risk asymptomatic patients (Level of Evidence: B) [1]
  • 2. Exercise myocardial perfusion SPECT as the initial test in patients who are considered to be at high risk (patients with diabetes or patients otherwise defined as having a more than 20% 10-year risk of a coronary heart disease event) (Level of Evidence: B) [1]

Class IIb

  • 1. Repeat exercise myocardial perfusion SPECT 1 to 3 years after initial perfusion imaging in patients with known or a high likelihood of CAD and stable symptoms and a predicted annual mortality of more than 1% to redefine the risk of a cardiac event (Level of Evidence: C) [1]
  • 2. Repeat exercise myocardial perfusion SPECT on cardiac active medications after initial abnormal perfusion imaging to assess the efficacy of medical therapy (Level of Evidence: C) [1]
  • 3. Exercise myocardial perfusion SPECT in symptomatic or asymptomatic patients who have severe coronary calcification (computed tomography [CT] coronary calcium score more than the 75th percentile for age and sex) in the presence on the resting ECG of pre-excitation [Wolff-Parkinson-White syndrome] or more than 1 mm ST-segment depression (Level of Evidence: B) [1]
  • 4. Exercise myocardial perfusion SPECT in asymptomatic patients who have a high-risk occupation. (Level of Evidence: B) [1]

Cardiac Stress Myocardial Perfusion SPECT in Patients Unable to Exercise

Recommendations for Diagnosis of Patients With an Intermediate Likelihood of CAD and/or Risk Stratification of Patients With an Intermediate or High Likelihood of CAD Who Are Unable to Exercise.

Class I

  • 1. Adenosine or dipyridamole myocardial perfusion SPECT to identify the extent, severity, and location of ischemia. (Level of Evidence: B) [1]
  • 2. Adenosine or dipyridamole myocardial perfusion SPECT to assess the functional significance of intermediate (25 to 75%) coronary lesions (Level of Evidence: B) [1]
  • 3. Adenosine or dipyridamole myocardial perfusion SPECT after initial perfusion imaging in patients whose symptoms have changed to redefine the risk for cardiac event (Level of Evidence: C) [1]

Class IIa

  • 1. Adenosine or dipyridamole myocardial perfusion SPECT at 3 to 5 years after revascularization (either PCI or CABG) in selected high-risk asymptomatic patients (Level of Evidence: B) [1]
  • 2. Adenosine or dipyridamole myocardial perfusion SPECT as the initial test in patients who are considered to be at high risk (patients with diabetes or patients otherwise defined as having a more than 20% 10-year risk of a coronary heart disease event). (Level of Evidence: B) [1]
  • 3. Dobutamine myocardial perfusion SPECT in patients who have a contraindication to adenosine or dipyridamole (Level of Evidence: C) [1]

Class IIb

  • 1. Repeat adenosine or dipyridamole myocardial perfusion imaging 1 to 3 years after initial perfusion imaging in patients with known or a high likelihood of CAD and stable symptoms, and a predicted annual mortality of more than 1%, to redefine the risk of a cardiac event (Level of Evidence: C) [1]
  • 2. Repeat adenosine or dipyridamole myocardial perfusion SPECT on cardiac active medications after initial abnormal perfusion imaging to assess the efficacy of medical therapy (Level of Evidence: C) [1]
  • 3. Adenosine or dipyridamole myocardial perfusion SPECT in symptomatic or asymptomatic patients who have severe coronary calcification (CT Coronary Calcium Score more than the 75th percentile for age and sex) in the presence on the resting ECG of LBBB or an electronically-paced ventricular rhythm (Level of Evidence: B) [1]
  • 4. Adenosine or dipyridamole myocardial perfusion SPECT in asymptomatic patients who have a high-risk occupation (Level of Evidence: C) [1]

Cardiac Stress Perfusion Imaging Before Noncardiac Surgery

Class I

  • 1. Initial diagnosis of CAD in patients with intermediate pretest probability of disease and abnormal baseline ECG* or inability to exercise (Level of Evidence: B) [1]
  • 2. Prognostic assessment of patients undergoing initial evaluation for suspected or proven CAD with abnormal baseline ECG* or inability to exercise (Level of Evidence: B) [1]
  • 3. Evaluation of patients following a change in clinical status (e.g., acute coronary syndrome [ACS]) with abnormal baseline ECG* or inability to exercise (Level of Evidence: B) [1]
  • 4. Initial diagnosis of CAD in patients with LBBB and intermediate pretest probability of disease, when used in conjunction with vasodilator stress (Level of Evidence: B) [1]
  • 5. Prognostic assessment of patients with LBBB undergoing initial evaluation for suspected or proven CAD, when used in conjunction with vasodilator stress (Level of Evidence: B) [1]
  • 6. Assessment of patients with intermediate or minor clinical risk predictors** and poor functional capacity (less than 4 metabolic equivalent [METS]) who require high-risk noncardiac surgery***, when used in conjunction with pharmacologic stress (Level of Evidence: C)[1]
  • 7. Assessment of patients with intermediate clinical risk predictors**, abnormal baseline ECGs*, and moderate or excellent functional capacity (more than 4 METS) who require high-risk noncardiac surgery (Level of Evidence: C) [1]

Baseline ECG abnormalities that interfere with interpretation of exercise-induced ST-segment changes include LBBB, ventricular pre-excitation, ventricular pacing, LVH with repolarization changes, more than 1-mm ST depression, and digoxin therapy.

As defined in the ACC/AHA Guideline Update for Perioperatiave Cardiovascular Evaluation for Noncardiac Surgery, intermediate clinical risk predictors include mild angina, prior myocardial infarction (MI), compensated or prior heart failure, diabetes, and renal insufficiency. Minor clinical risk predictors include advanced age, abnormal ECG, rhythm other than sinus, low functional capacity, history of cerebrovascular accident, and uncontrolled hypertension.

High-risk surgery is defined by emergent operations (particularly in the elderly), aortic and other major vascular surgery, peripheral vascular surgery, and other prolonged operations in which major fluid shifts are anticipated (i.e., reported cardiac risk often more than 5%).

Class IIb

  • 1. Routine assessment of active, asymptomatic patients who have remained stable for up to 5 years after CABG surgery (Level of Evidence: C) [1]
  • 2. Routine evaluation of active asymptomatic patients who have remained stable for up to 2 years after previous abnormal coronary angiography or noninvasive assessment of myocardial perfusion (Level of Evidence: C) [1]
  • 3. Diagnosis of restenosis and regional ischemia in active asymptomatic patients within weeks to months after PCI (Level of Evidence: C)[1]
  • 4. Initial diagnosis or prognostic assessment of CAD in patients with right bundle-branch block or less than 1-mm ST depression on resting ECG (Level of Evidence: C) [1]

Class III

  • 1. Routine screening of asymptomatic men or women with low pretest likelihood of CAD (Level of Evidence: C)[1]
  • 2. Evaluation of patients with severe comorbidities that limit life expectancy or candidacy for myocardial revascularization (Level of Evidence: C)[1]
  • 3. Initial diagnosis or prognostic assessment of CAD in patients who require emergency noncardiac surgery (Level of Evidence: C)[1]

Use of Radionuclide Imaging in Patients With Heart Failure: Fundamental Assessment

Class I

  • Rest RNA for initial assessment of LV and RV function at rest I (A) [1]
  • MPI and PET for assessment of myocardial viability for consideration of revascularization in patients with CAD and LV systolic dysfunction who do not have angina I (B)[1]

Class IIa

  • MPI for assessment of the co-presence of CAD in patients without angina. IIa (B) [1]

Class IIb

  • Rest RNA for routine serial assessment of LV and RV function at rest IIb (B) [1]
  • Exercise RNA for initial or serial assessment of ventricular function with exercise IIb (B) [1]

Use of Radionuclide Techniques to Assess Myocardial Viability

Class I

  • 1. Predicting improvement in regional and global LV function after revascularization: Stress/redistribution/reinjection 201TI (I B) [1], rest redistribution imaging (I B) [1], perfusion plus PET FDG imaging (I B) [1]and resting sestamibi imaging (I B) [1].
  • 2. Predicting improvement in natural history after revascularization: 201TI imaging (rest-redistribution and stress / redistribution / reinjection) (I B) [1]

Class IIa

  • 1. Gated SPECT sestamibi imaging for predicting improvement in regional and global LV function after revascularization: (IIa B)[1]
  • 2. Perfusion plus PET FDG imaging for predicting improvement in heart failure symptoms after revascularization. (IIa B) [1]

Class IIb

  • 1. Predicting improvement in regional and global LV function after revascularization: Late 201Tl redistribution imaging (after stress) (IIb B) [1], Dobutamine RNA (IIb C)[1], Postexercise RNA (IIb C)[1], Postnitroglycerin RNA (IIb C) [1]

Use of Radionuclide Imaging to Diagnose Specific Causes of Dilated Cardiomyopathy

Class I

  • 1. Rest RNA for baseline and serial monitoring of LV function during therapy with cardiotoxic drugs (e.g., doxorubicin) I (A) [1]

Class IIa

  • 1. Rest RNA for detecting RV dysplasia IIa (B) [1]

Class IIb

  • 1. Exercise perfusion imaging for assessment of post-transplant obstructive CAD. IIb (B) [1]
  • 2. Exercise perfusion imaging for diagnosis and serial monitoring of Chagas disease. IIb (B) [1]
  • 3. 99mTc-pyrophosphate imaging for diagnosis of amyloid heart disease. IIb (B) [1]
  • 4. Rest perfusion imaging for diagnosis and serial monitoring of sarcoid heart disease. IIb (B)[1]
  • 5. Rest 67Ga imaging for diagnosis and serial monitoring of sarcoid heart disease. IIb (B)[1]
  • 6. Rest 67Ga imaging for detection of myocarditis. IIb (B)[1]
  • 7. 111In antimyosin antibody imaging for detection of myocarditis. IIb (C)[1]

Use of Radionuclide Imaging to Evaluate Hypertrophic Heart Disease

Class IIb

  • 1. Rest and exercise perfusion imaging for diagnosis of CAD in hypertrophic cardiomyopathy. IIb (B)[1]
  • 2. Rest RNA for diagnosis and serial monitoring of hypertensive hypertrophic heart disease. IIb (B)[1]

Class III

  • 1. Rest RNA for diagnosis and serial monitoring of hypertrophic cardiomyopathy, with and without outflow obstruction. III (B)[1]

Use of Radionuclide Imaging in Valvular Heart Disease

Class I

  • 1. Rest RNA for initial and serial assessment of LV and RV function. I (B)[1]

Class IIb

  • 1. Exercise RNA for initial and serial assessment of LV function. IIb (B)[1]
  • 2. MPI for assessment of the copresence of coronary disease. IIb (B)[1]

Use of Radionuclide Imaging in Adults with Congenital Heart Disease

Class I

  • 1. Rest RNA for initial and serial assessment of LV and RV function. I (B) [1]

Class IIa

  • 1. First pass radionuclide angiography (FPRNA) for shunt detection and quantification. IIa (B) [1]

Cardiac Stress Myocardial Perfusion Positron Emission Tomography (PET)

Recommendations for Diagnosis of Patients With an Intermediate Likelihood of CAD and/or Risk Stratification of Patients With an Intermediate or High Likelihood of CAD

Class I

  • 1. Adenosine or dipyridamole myocardial perfusion PET in patients in whom an appropriately indicated myocardial perfusion SPECT study has been found to be equivocal for diagnostic or risk stratification purposes (Level of Evidence: B) [1]

Class IIa

  • 1. Adenosine or dipyridamole myocardial perfusion PET to identify the extent, severity, and location of ischemia as the initial diagnostic test in patients who are unable to exercise (Level of Evidence: B) [1]
  • 2. Adenosine or dipyridamole myocardial perfusion PET to identify the extent, severity, and location of ischemia as the initial diagnostic test in patients who are able to exercise but have LBBB or an electronically-paced rhythm (Level of Evidence: B) [1]

Potential Benefits

  • Appropriate use of testing and technology in the diagnosis and treatment of patients with known or suspected cardiovascular disease
  • Decreased morbidity and mortality associated with cardiovascular disease due to contribution of radionuclide imaging studies in the diagnosis, assessment of severity of disease/risk assessment/prognosis, and assessment of therapy

Potential Harms

Dipyridamole and Adenosine

Both dipyridamole and adenosine are safe and well tolerated despite frequent mild side effects, which occur in 50% and 80% of patients, respectively. With dipyridamole infusion, the most common side effect is chest pain (18 to 42%), with arrhythmia occurring in less than 2%. Noncardiac side effects have included headache (5 to 23%), dizziness (5 to 21%), nausea (8 to 12%), and flushing (3%). With adenosine infusion, chest pain has been reported in 57%, headache in 35%, flushing in 25%, shortness of breath in 15%, and first-degree atrioventricular block in 18%. The side effects of adenosine or dipyridamole are less frequent when vasodilator stress is combined with low-level exercise. Dipyridamole and adenosine side effects are antagonized by theophylline; however, this drug is ordinarily not needed after adenosine because of the latter’s ultrashort half-life (less than 10 seconds). The ability of these drugs to cause coronary vasodilation can be blocked by caffeine and other methylxanthines. Thus, patients are instructed to avoid these agents for 24 hours before testing.

Dobutamine

Although side effects are frequent during dobutamine infusion, the test appears to be relatively safe, even in the elderly. The most frequently reported noncardiac side effects (total 26%) in a study of 1,118 patients included nausea (8%), anxiety (6%), headache (4%), and tremor (4%) (497). Common arrhythmias included premature ventricular beats (15%), premature atrial beats (8%), supraventricular tachycardia, and nonsustained ventricular tachycardia (3 to 4%). Atypical chest pain was reported in 8%, and angina pectoris in approximately 20%.

Contraindications

Severe side effects are rare, but both dipyridamole and adenosine may cause severe bronchospasm in patients with asthma or reactive airway disease; therefore, they are contraindicated in these patients.

Source

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40 1.41 1.42 1.43 1.44 1.45 1.46 1.47 1.48 1.49 1.50 1.51 1.52 1.53 1.54 1.55 1.56 1.57 1.58 1.59 1.60 1.61 1.62 1.63 1.64 1.65 1.66 1.67 1.68 1.69 1.70 1.71 1.72 1.73 1.74 1.75 1.76 1.77 1.78 1.79 1.80 1.81 1.82 Klocke FJ, Baird MG, Lorell BH, Bateman TM, Messer JV, Berman DS, O’Gara PT, Carabello BA, Russell RO Jr, Cerqueira MD, St John Sutton MG, DeMaria AN, Udelson JE, Kennedy JW, Verani MS, Williams KA, Antman EM, Smith SC Jr, Alpert JS, Gregoratos G, Anderson JL, Hiratzka LF, Faxon DP, Hunt SA, Fuster V, Jacobs AK, Gibbons RJ, Russell RO; American College of Cardiology; American Heart Association Task Force on Practice Guidelines; American Society for Nuclear Cardiology. ACC/AHA/ASNC guidelines for the clinical use of cardiac radionuclide imaging–executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASNC Committee to Revise the 1995 Guidelines for the Clinical Use of Cardiac Radionuclide Imaging). Circulation 2003 Sep 16; 108 (11): 1404-18. PMID 12975245



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Exercise / Pharmacologic Stress Echocardiography

Exercise / Pharmacologic Stress Echocardiography

  • Strengths
    • Higher sensitivity and specificity than exercise EKG: Metanalysis showed sensitivity of 84%, specificity 86%. Marked variation across trials though, highly operator dependent. If the max heart rate is < 85% of age predicted, then sensitivity drops to 42%. Sensitivity is 10% lower in women than in men, specificity is the same across genders. In women with single vessel disease the sensitivity was only 40%, if there was 2 or 3 vessel disease, this number increased to 60%.
    • Additional prognostic value over exercise EKG
    • Dobutamine stress has higher sensitivity than does pharmacologic stress
    • Time to complete examination is short
    • Identification of co-existent structural cardiac abnormalities (valvular disease)
    • Simultaneous evaluation of perfusion with contrast agents
    • Relatively lower costs than with other techniques
    • No radiation
  • Limitations
    • Decreased sensitivity for the detection of single vessel disease or mild stenosis with post exercise imaging
    • Inability to image the entire ventricle in some patients
    • Highly operator dependent in the analysis of images
    • No quantitative image analysis
    • Poor windows in patients with COPD
    • Infarct zone ischemia less well detected

Editor(s)-In-Chief: C. Michael Gibson M.S., M.D. [1] Phone:617-525-6884 ; Eli V. Gelfand, M.D. [2]

Overview

Echocardiography

  • Echocardiography (echo) is a test that uses sound waves to create a moving picture of your heart. The picture shows how well your heart is working and its size and shape. There are several types of echo, including stress echo.
  • Stress echo can show whether you have decreased blood flow to your heart, a sign of coronary heart disease. Another type of echo is transesophageal (tranz-ih-sof-uh-JEE-ul) echo, or TEE.
  • TEE provides a view of the back of the heart. For this test, a sound wave wand is put on the end of a special tube. The tube is gently passed down your throat and into your esophagus (the passage leading from your mouth to your stomach). Because this passage is right behind the heart,

General Principles of Echocardiography

Principal Echocardiographic Modalities

Echocardiographic Diagnosis and Evaluation of Specific Cardiovascular Disorders

Miscellaneous

References


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Comparison of exercise SPECT imaging and Exercise Echocardiography

Comparison of exercise SPECT imaging and Exercise Echocardiography

  • Both have a higher sensitivity and specificity than regular exercise EKG testing
  • Both provide functional information that EKG testing does not
  • Both provide information about myocardial viability, which the angiogram does not
Strengths of Stress ECHO over SPECT

Strengths of Stress ECHO over SPECT

  • Noninvasive, safe and repeatable, no radiation exposure, quick, little sophisticated equipment and portable, low costs, can identify co-existing valvular heart disease
Limitations of Stress ECHO over SPECT

Limitations of Stress ECHO over SPECT

  • Images are difficult to obtain at peak exercise, an ischemic response is required to observe wall motion abnormalities, wall motion can recover quickly in the presence of mild ischemia, detection of residual ischemia is difficult in an akinetic wall zone, the technique is highly operator dependent, good quality images were only acquired in 70% of cases.
Strengths of SPECT over stress ECHO

Strengths of SPECT over stress ECHO

  • Does not require an ischemic response to be abnormal, just requires an abnormality in flow reserve, sensitivity is slightly higher by about 8-10 percentage points (mostly because the ability to detect single vessel disease or mild stenoses of 50-70% is not as good with stress Echo), can see defects in areas that contain scar and viable myocardium, acquisition of images is not operator dependent, in virtually 100% of patients diagnostic images are obtained, with Tc simultaneous assessment of perfusion and function is obtained, resting LV ejection fraction can be obtained, vasodilator SPECT has significantly higher sensitivity than vasodilator stress ECHO, dobutamine ECHO is associated with higher sensitivity and specificity than vasodilator ECHO.
Limitations of SPECT imaging in relation to stress ECHO

Limitations of SPECT imaging in relation to stress ECHO

  • Longer imaging protocols, greater expense of equipment, must inject and store radiopharmaceuticals, inability to visualize the heart in real time, lower spatial resolution than ECHO, higher costs to patients.

In general, the sensitivity is lower for stress ECHO while the specificity is higher.

Prognosis

Prognosis

Exercise Tolerance Testing

  • 1 mm or more of horizontal or downsloping ST depression is associated with a poor prognosis
  • Failure to achieve 6 METS is associated with an elevated mortality rate over the next 2.5 years.
  • Failure of heart rate to rise is associated with higher mortality, even after adjusting for perfusion defects.
  • Failure to reach 85% of age adjusted max HR is associated with a RR of 1.85 in mortality.
  • Limitation of ETT is the fact that the magnitude of ST depression is not strongly associated with the extent of CAD
  • Exercise testing alone has excellent prognostic ability among patients with atypical chest pain or non anginal pain who have a normal EKG at baseline. If these patients have a normal ETT, the prognosis is excellent.
Nuclear Stress Myocardial Perfusion

Nuclear Stress Myocardial Perfusion

  • Nuclear Stress Myocardial Perfusion Imaging, often abbreviated MPI or MPS, is a technique for measuring perfusion of myocardial tissue using externally injected radioactive tracers. Photons, or positrons emitted from these tracers are then detected with specialized imaging equipment and software. The most common methods are single photon emission computed tomography (SPECT) and positron emission tomography (PET). SPECT can be performed with radiotracers based on thallium or technetium 99-m. PET is commonly performed with rubidium-82, although some centers use ammonia (NH3) or radiolabeled oxygen in water. Cardiac PET with fluorodeoxyglucose (FDG) is useful for other investigations such as evaluation of infections, sarcoidosis activity, and viability/hibernation. Flurpiridaz, is a PET tracer based on fluorine-18 (F-18) and was approved for use by the FDA in 2025.
  • The following are associated with a poor prognosis:
    • 20% of the LV is a perfusion defect
    • Defects in more than one distribution suggestive of multivessel CAD
    • A large number of non reversible defects
    • Transient LV cavitary dilation
    • Increased lung uptake
    • Resting LVEF of < 40%
  • Normal thallium: Mortality 1% per year
  • Normal Tc: annual mortality 0.6%, 12 fold higher if there is a Tc defect
  • The positive predictive value of stress myocardial perfusion imaging and stress ECHO is low: That is the percentage of people who die or sustain an MI is low among patients with abnormal findings. On the other hand the negative predictive value is high and exceeds 95%.
Techniques used to Assess Myocardial Viability

Techniques used to Assess Myocardial Viability

  • Tl Imaging
    • Rest and delayed redistribution is the most common radionuclide method used to assess viability. Uptake of Tl is related not only to blood flow, but also to membrane integrity. Myocardial stunning or hibernation does not result in a reduction in Tl extraction as long as the sarcolemmal membrane does not sustain irreversible ischemic damage. 60 to 70% of asynergistic segments will show > a 50% improvement after revascularization.
  • Tc Imaging
    • Same as above, as usual a better signal with Tc, can also assess regional wall thickening. If thickening is present, then viability is likely.
  • PET
    • Considered by many to be the gold standard. Can be used to assess perfusion and metabolism simultaneously. If there is mismatch in perfusion and metabolism, then the tissue is viable. If there is a match, then there is scar.

Dobutamine: Enhanced systolic contractility with low dose dobutamine is associated with recovery.



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