Simultaneous non-contact mapping fused with CMR derived grey zone to explore the relationship with ventricular tachycardia substrate in ischaemic cardiomyopathy

Background Cardiac magnetic resonance (CMR) imaging enables characterization of myocardial scar and the ‘grey zone’, an admixture of scar and healthy myocardium, which is an independent predictor of ventricular arrhythmia. We explored the relationship between the grey zone and ventricular tachycardia circuits (VT) in ischaemic cardiomyopathy. Methods Two patients with previous myocardial infarct underwent high-resolution late gadolinium enhanced CMR scar imaging (1.2x1.2x2.6mm) and a VT-stimulation study. The LV scar core was segmented using full-width-half-maximum method; and the grey zone was segmented with a cut-off signal intensity below that of the scar core and above 2 standard-deviation of the remote healthy myocardium. A multi-electrode array (MEA) was positioned in the LV cavity for simultaneous electroanatomical mapping during the study. The MEA shell was registered with the CMR-derived LV shell using anatomical landmark registration (Figure 1a,b) for comparison. Results Sustained monomorphic VT (SMVT) was induced in both patients. Scar core and grey zone regions correlated well with the low voltage area (≤ 30% maximum voltage) seen on the MEA (Figure 1a,c,d). The exit point during SMVT