Cardiac computed tomography
Alternatively to LGE CMR, in patients with intracardiac devices not compatible with it, LV wall motion and scar assessment is done using contrast enhanced multiphasic 4D computed tomography (CT). Even in patients with MRI conditional devices, 4D CT may be better for regional motion assessment of the interventricular septum, mainly in patients with pacemaker / implantable cardioverter defibrillator (ICD) / cardiac resynchronization therapy (CRT) leads placed in the right side of it. Despite not having direct scar determination capabilities, 4D multiphasic CT scan is a powerful tool in regional wall thickness and motion assessment as well as LV volume assessment.[8] Thinned, akinetic or dyskinetic regions are considered non-viable and, as such, suitable for exclusion with the LIVE technique. Although sensitivity and specificity are lower than LGE CMR, existence of an apical thrombus can also be assessed by CT.[9] Extensive LV wall calcification is an absolute contraindication for the procedure and can be easily depicted from CT, and not from CMR. Additionally, 3D multiphasic volume rendering is an important tool in determining scar location, assessing basal wall contractility and precise planning of anchor placement. Finally, 4D CT is useful in assessing graft positioning in post-coronary artery bypass graft (CABG) patients. Figure 4 summarizes key aspects in 4D multiphasic CT screening for the LIVE procedure.