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Published on: October 14, 2016
Diagnosis of coronary artery disease by exercise thallium-201 tomography in patients with a right ventricular
N M Lakkis1, Z X He, M S Verani
1Department of Medicine, Baylor College of Medicine, Houston, Texas, USA.
Insights
Exercise perfusion scintigraphy can show false positive defects in patients with right ventricular pacemakers. Continuous pacing during the test increases the likelihood of these inaccurate results.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Left bundle branch block can decrease exercise perfusion scintigraphy specificity.
- Permanent ventricular pacemakers may cause similar false positive perfusion defects due to conduction abnormalities.
Purpose of the Study:
- To evaluate the accuracy of exercise perfusion scintigraphy in patients with apical right ventricular pacemakers.
- To determine if pacemaker use affects scintigraphy results.
Main Methods:
- 105 patients with right ventricular pacemakers underwent exercise thallium-201 tomography and coronary angiography within 7 days.
- Patients with prior myocardial infarction were excluded from the study.
Main Results:
- 78% of patients with normal coronary angiography but abnormal scintigraphy were continuously paced.
- False positive defects were common, particularly in the inferoposterior, apical, and inferoseptal walls.
- Only 8% of patients with concordantly normal results were continuously paced.
Conclusions:
- Continuous right ventricular apical pacing during exercise perfusion scintigraphy leads to a high rate of false positive thallium-201 single-photon emission computed tomographic defects.
- These findings suggest that pacemaker activity can significantly impact the interpretation of myocardial perfusion imaging.
Objectives:
We sought to study the accuracy of exercise perfusion scintigraphy in patients with an implanted apical right ventricular pacemaker.
Background:
The specificity of exercise perfusion scintigraphy is decreased in patients with a left bundle branch block. Patients with a permanent ventricular pacemaker have a similar conduction abnormality that may also potentially result in similar false positive perfusion defects.
Methods:
One hundred five patients with a right ventricular pacemaker underwent exercise thallium-201 tomography and coronary angiography within 7 days of each other. Patients with a previous myocardial infarction were excluded.
Results:
Patients were classified into four groups according to the agreement or disagreement between the thallium tomographic and coronary angiographic results. Only 8% of patients with normal results by both techniques were continuously paced during exercise, compared with 78% of patients with normal angiographic results but abnormal scintigraphic results. The mean defect size was 12% in the latter group. Most of the false positive defects were localized to the inferoposterior (71%), apical (50%) and inferoseptal (28%) walls.
Conclusions:
Patients who are paced in the right ventricular apex and who continue to be paced throughout exercise have a high incidence of false positive thallium-201 single-photon emission computed tomographic defects.
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