PSEUDOINFARCTION AFTER PLACEMENT OF AN EP ICARDIAL ICD PATCH ELECTRODE - DIFFERENTIATION BY SPECT AND PET

A 64-year-old male who received an implantable cardioverter defibrilla tor with epicardial patch electrodes in 1990 was admitted to the emerg ency room because of recurrent defibrillator shocks. During the follow ing diagnostic work-up a remarkable discrepancy between coronary angio graphy (no significant stenosis), (201)Thallium-SPECT imaging (antero- septal persistent defect) and PET imaging (no (18)FDG defect) was noti ced. In order to assess the impact of the epicardial defibrillator pat ch electrodes on the imaging, we performed SPECT and PET measurements using a thorax phantom. We found that in Tl-201-SPECT an epicardial pa tch caused a significant (up to 20%) photon attenuation, which may lea d to the phenomenon of ''pseudoinfarction''. On PET images epicardial patch electrodes failed to produce any significant attenuation artifac ts suggestive of infarction.