1010-67 Effect of Subcutaneous Implantable Cardiac Defibrillator Patches on TI-201 Myocardial Imaging

Abstract

Subcutaneous patches are frequently used with nonthoracotomy implantable cardiac defibrillator (ICD) devices. The effect of these patches on thallium imaging for the evaluation of myocardial ischemia is unknown. This study evaluated the attenuation effects of two commercially available subcutaneous ICD patches on TI-201 myocardial tomograms. Two sets of post-reinjection TI-201 tomograms, with and without ICD patches (Medtronic or CPI), were obtained in 29 patients undergoing routine exercise or dipyridamole TI-201 stress testing. Patches were positioned over the anterior, mid, or posterior axillary line in the fourth intercostal space. Gated planar TI-201 images with and without patches were used to determine the presence of preserved regional wall motion in the area of the patch-induced attenuation defect. Readers were blinded to the patch type, location, and order of imaging, which were all randomized. Two independent readers: (1) inspected the 2 sets of the 32 raw images from the 180° acquisition to determine if the patch was visible, (2) interpreted 2 sets of tomograms for defects, and (3) assessed regional wall motion in the area of the defect. Patch location could be identified in 42% of patients with CPI patches and 71% with Medtronic patches. Attenuation defects were observed in 6 patients (35%) with Medtronic patches and 4 patients (33%) with CPI patches. In the subset of patients with patch-induced defects, preserved wall motion was present in 89% of these regions. Subcutaneous patches can cause attenuation defects which may be mistaken as an area of infarction. Normal wall motion on gated images allows differentiation between attenuation artifacts due to the patches from fixed defects due to infarction.