Cardiac radionuclide imaging
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:
- Diagnosis of coronary artery disease,
- Evaluation of cardiac function abnormalities,
- Monitoring of patients under treatment for establishing cardiac disease.
- Verification of the diagnosis of acute myocardial infarction
Current available modalities are:

## Myocardial perfusion imaging (MPI)
- Stress imaging through:
- Exercise (treadmill or upright or supine bicycle)
- Pharmacologic modalities
- Vasodilators (dipyridamole and adenosine)
- Dobutamine
- Consider concomitant use of drugs (e.g., beta adrenergic agents, calcium channel blockers, nitrates, caffeine)
- Perfusion tracers:
- 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) 
- 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) 

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

# 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) 
- MPI at rest or with stress using gated SPECT for assessment of infarct size and residual viable myocardium in STEMI patients I (B) 
- Stress MPI with ECG-gated SPECT whenever possible for detection of inducible ischemia and myocardium at risk after thrombolytic therapy without catheterization	I (B) 

## Class IIa
- Equilibrium or FPRNA for assessment of RV function with suspected RV infarction in STEMI. IIa (B) 

# 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) 
- 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) 
- Stress MPI for identification of hemodynamic significance of coronary stenosis after coronary arteriography. I (B) 
- RNA or gated SPECT for measurement of baseline LV function. I (B) 

## 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) 

# 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 , digoxin therapy, or more than 1-mm ST depression) (Level of Evidence: B) 
- 2. Adenosine or dipyridamole myocardial perfusion SPECT in patients with LBBB or electronically-paced ventricular rhythm (Level of Evidence: B) 
- 3. Exercise myocardial perfusion SPECT to assess the functional significance of intermediate (25 to 75%) coronary lesions (Level of Evidence: B) 
- 4. Exercise myocardial perfusion SPECT in patients with intermediate Duke treadmill score (Level of Evidence: B) 
- 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) 

## Class IIa
- 1. Exercise myocardial perfusion SPECT at 3 to 5 years after revascularization (either percutaneous coronary intervention  or coronary artery bypass graft surgery ) in selected high-risk asymptomatic patients (Level of Evidence: B) 
- 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) 

## 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) 
- 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) 
- 3. Exercise myocardial perfusion SPECT in symptomatic or asymptomatic patients who have severe coronary calcification (computed tomography  coronary calcium score more than the 75th percentile for age and sex) in the presence on the resting ECG of pre-excitation  or more than 1 mm ST-segment depression (Level of Evidence: B) 
- 4. Exercise myocardial perfusion SPECT in asymptomatic patients who have a high-risk occupation. (Level of Evidence: B) 

# 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) 
- 2. Adenosine or dipyridamole myocardial perfusion SPECT to assess the functional significance of intermediate (25 to 75%) coronary lesions (Level of Evidence: B) 
- 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) 

## 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) 
- 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) 
- 3. Dobutamine myocardial perfusion SPECT in patients who have a contraindication to adenosine or dipyridamole (Level of Evidence: C) 

## 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) 
- 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) 
- 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) 
- 4. Adenosine or dipyridamole myocardial perfusion SPECT in asymptomatic patients who have a high-risk occupation (Level of Evidence: C) 

# 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) 
- 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) 
- 3. Evaluation of patients following a change in clinical status (e.g., acute coronary syndrome ) with abnormal baseline ECG- or inability to exercise (Level of Evidence: B) 
- 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) 
- 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) 
- 6. Assessment of patients with intermediate or minor clinical risk predictors and poor functional capacity (less than 4 metabolic equivalent ) who require high-risk noncardiac surgery*, when used in conjunction with pharmacologic stress (Level of Evidence: C)
- 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) 
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) 
- 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) 
- 3. Diagnosis of restenosis and regional ischemia in active asymptomatic patients within weeks to months after PCI (Level of Evidence: C)
- 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) 

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

# 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) 
- 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)

## Class IIa
- MPI for assessment of the co-presence of CAD in patients without angina. IIa (B) 

## Class IIb
- Rest RNA for routine serial assessment of LV and RV function at rest IIb (B) 
- Exercise RNA for initial or serial assessment of ventricular function with exercise IIb (B) 

# 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) , rest redistribution imaging (I B) , perfusion plus PET FDG imaging (I B) and resting sestamibi imaging (I B) .
- 2. Predicting improvement in natural history after revascularization: 201TI imaging (rest-redistribution and stress / redistribution / reinjection) (I B) 

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

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

# 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) 

## Class IIa
- 1. Rest RNA for detecting RV dysplasia IIa (B) 

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

# 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)
- 2. Rest RNA for diagnosis and serial monitoring of hypertensive hypertrophic heart disease. IIb (B)

## Class III
- 1. Rest RNA for diagnosis and serial monitoring of hypertrophic cardiomyopathy, with and without outflow obstruction. III (B)

# 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)

## Class IIb
- 1. Exercise RNA for initial and serial assessment of LV function. IIb (B)
- 2. MPI for assessment of the copresence of coronary disease. IIb (B)

# 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) 

## Class IIa
- 1. First pass radionuclide angiography (FPRNA) for shunt detection and quantification. IIa (B) 

# 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) 

## 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) 
- 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) 

# 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
- National Guideline Clearinghouse