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.