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.