Fig. 3

Cardiovascular MRI scan. The 4-chamber cine image showed proximal septal thickening (purple arrows) and the artifacts of the leads (yellow arrows). Late gadolinium enhancement images displayed a patchy non-ischemic mid-myocardial high signal intensity in the same proximal septum (purple arrows). T1 mapping demonstrated focal high T1 values in the proximal septum of 1263 ± 51ms (site-specific normal myocardial T1 values: 950–1050ms). On the CT scan, the lead artifacts are distinctly discernible (purple arrow is the LBBA lead, yellow arrow is the RV lead), providing a clear indication of the point at which the lead was inserted into the right ventricular septum. The insertion site aligns with the corresponding late gadolinium enhancement images within the same image plane. Notably, the late gadolinium enhancement exhibits a broader extent than the lead insertion site, encompassing both the infero-antero septal and basal-to-mid septal directions