Chronic stable angina perfusion scintigraphy with pharmacologic stress

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org] Phone:617-632-7753; Associate Editor(s)-In-Chief: ; Smita Kohli, M.D.; Lakshmi Gopalakrishnan, M.B.B.S.

Overview
Pharmacologic stress testing using myocardial perfusion scintigraphy or echocardiography can be employed in patients with known or suspected angina pectoris who are unable to perform adequate exercise tests. These patients often owe their ineligibility status to associated conditions such as: peripheral vascular disease, musculoskeletal disorders, diseases of the lower extremities, severe obesity, or deconditioning. Pharmacologic stress testing is achieved with the infusion of either dobutamine in incremental dose, which acts by increasing myocardial oxygen consumption and thereby mimic effect of exercise, or with the use of coronary vasodilators such as adenosine or dipyridamole, which acts by differentiating regions based on perfusion. Stress imaging is of great value in the evaluation of patients with low pretest probability of CAD. However, in patients with LBBB, perfusion scintigraphy is shown to have poor diagnostic accuracy.

Diagnostic criteria

 * Non-endothelium dependent coronary vasodilators such as dipyridamole or adenosine can be used to increase flow to the non-ischemic myocardial segments. During the test, vasodilators may produce perfusion defects in ischemic areas that can be detected by scintigraphy.


 * Alternatively, dobutamine can be used to increase heart rate and contractility, which increases myocardial oxygen demand and may compromise perfusion of ischemic areas; the resultant ischemia can be detected by perfusion scintigraphy. Dobutamine may cause true myocardial ischemia, not simply a relative increase in flow to nonischemic myocardium. Hence, it must be administered carefully with close monitoring and rapid cessation for potential symptomatic ischemia.

Sensitivity and specificity

 * All three of these pharmacologic stress tests have diagnostic accuracies (sensitivity, specificity, and predictive values) comparable with those of exercise perfusion scintigraphy.


 * Dobutamine stress echocardiography has a sensitivity of 40-100% and a specificity of 62-100%.


 * Vasodilator perfusion scintigraphy has a sensitivity and specificity of 56-92% and 87-100%, respectively.
 * Adenosine SPECT has a sensitivity of 83-94% and a specificity of 64-90%.

Adverse effects of the test

 * Both dipyridamole and adenosine produce similar side effects, which consist of:
 * Bronchospasm
 * Flushing
 * Dizziness
 * Headache
 * Nausea
 * Atypical chest pain
 * Throat or jaw pain


 * Dipyridamole infusion has been reported to induce severe myocardial ischemia and, rarely, myocardial infarction. Special care should be taken to ensure patients are not already on dipyridamole.


 * Adenosine, on the other hand, can produce significant bradyarrhythmias. Adenosine stress tests are therefore contraindicated in patients with atrioventricular block and sick sinus syndrome.
 * In patients with bronchial asthma, dipyridamole is a preferred choice as adenosine precipitates bronchospasm.

==ACC / AHA Guidelines- Cardiac Stress Imaging as the Initial Test for Diagnosis in Patients With Chronic Stable Angina Who Are Unable to Exercise (DO NOT EDIT) == {{cquote|

Class I
1. Adenosine or dipyridamole myocardial perfusion imaging or dobutamine echocardiography in patients with an intermediate pretest probability of CAD. (Level of Evidence: B)

2. Adenosine or dipyridamole stress myocardial perfusion imaging or dobutamine echocardiography in patients with prior revascularization (either PTCA or CABG). (Level of Evidence: B)

Class IIb
1. Adenosine or dipyridamole stress myocardial perfusion imaging or dobutamine echocardiography in patients with a low or high probability of CAD in the absence of electronically paced ventricular rhythm or left bundle-branch block. (Level of Evidence: B)

2. Adenosine or dipyridamole myocardial perfusion imaging in patients with a low or high probability of CAD and 1 of the following baseline ECG abnormalities:
 * a. Electronically paced ventricular rhythm. (Level of Evidence: C)
 * b. Left bundle-branch block. (Level of Evidence: B)}}

==ESC Guidelines- Exercise stress with imaging techniques (either echocardiography or perfusion) in the initial diagnostic assessment of angina (DO NOT EDIT) == {{cquote|

Class I
1. Patients with resting ECG abnormalities, LBBB, more than 1 mm ST-depression, paced rhythm, or WPW which prevent accurate interpretation of ECG changes during stress. (Level of Evidence: B)

2. Patients with a non-conclusive exercise ECG but reasonable exercise tolerance, who do not have a high probability of signiﬁcant coronary artery disease and in whom the diagnosis is still in doubt. (Level of Evidence: B)

Class IIa
1. Patients with prior revascularization (PCI or CABG) in whom localization of ischaemia is important. (Level of Evidence: B)

2. As an alternative to exercise ECG in patients where facilities, cost, and personnel resources allow. (Level of Evidence: B)

3. As an alternative to exercise ECG in patients with a low pre-test probability of disease such as women with atypical chest pain. (Level of Evidence: B)

4. To assess functional severity of intermediate lesions on coronary arteriography. (Level of Evidence: C)

5. To localize ischaemia when planning revascularization options in patients who have already had arteriography. (Level of Evidence: B)}}

Vote on and Suggest Revisions to the Current Guidelines

 * The Chronic Stable Angina Living Guidelines: Vote on current recommendations and suggest revisions to the guidelines

Guidelines Resources

 * The ACC/AHA/ACP–ASIM Guidelines for the Management of Patients With Chronic Stable Angina


 * Guidelines on the management of stable angina pectoris: The Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology


 * The ACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina


 * The 2007 Chronic Angina Focused Update of the ACC/AHA 2002 Guidelines for the Management of Patients With Chronic Stable Angina