Aims: Scar evaluation by late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) can assist ventricular tachycardia (VT) ablation, but co-registration with electro-anatomical maps (EAMs) and imaging artefact from implantable cardioverter defibrillators (ICDs) limit accuracy. We assessed the feasibility of using personalised co-registration algorithms to correlate low-voltage zones (LVZ) with optimised LGE-CMR scar imaging in patients with ICDs.
Methods: 10 patients planned for VT ablation underwent pre-procedural LGE-CMR using wideband imaging. Scar was segmented from CMR pixel signal intensity (PSI) maps using commercial software with new bespoke tools and compared to detailed EAMs. Spatial smoothing was applied to reduce noise in both PSI and voltage maps. Co-registration of EP and imaging derived scar was performed using the aorta as a fiducial marker and the impact of co-registration was determined using a test-retest strategy, and in simulations by shifting and rotating co-registered maps.
Results: PSI localized low-voltage zones (V <1.5 mV) with area under the ROC curve AUC=0.84 (0.80–0.88), sensitivity=79% (74–81%) and specificity=80% (74–85%) and it moderately correlated with bipolar voltage, r=-0.62 (-0.71 – -0.43) [Median (1st–3rd quartile) across patients]. In simulations, small random shifts and rotations significantly worsened LVZ localization in at least some cases, but the use of the full aortic geometry ensured high intra and inter-operator reproducibility of LVZ localization (r >0.86 for AUC). Results for LVZ with V <0.5 mV were similar.
Conclusion: In patients with CIEDs, novel wideband CMR sequences and personalised co-registration strategies can localize LVZ with good accuracy and may assist VT ablation procedures.