Accurate Conduction Velocity Maps and their Association with Scar Distribution on Magnetic Resonance Imaging in Patients with Post-Infarction Ventricular Tachycardias.

Background ischemic cardiomyopathy (ICM) and ventricular tachycardia (VT) is important for understanding the patient-specific pro-arrhythmic substrate of VTs and therapeutic planning. The objective of this study is to accurately assess the relation between CV and myocardial fibrosis density on late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) imaging in patients with ICM. Methods - We enrolled 6 patients with ICM undergoing VT ablation and 5 with structurally normal left ventricles (controls) undergoing PVC or VT ablation. All patients underwent LGE-CMR and electro-anatomical mapping (EAM) in sinus rhythm (2,960 EAM points analyzed). We estimated CV from EAM local activation time using the triangulation method, that provides an accurate estimate of CV as it accounts for the direction of wavefront propagation. We evaluated for the association between LGE-CMR intensity and CV with multi-level linear mixed models. Results - Median CV in ICM patients and controls was 0.41 m/s and 0.65 m/s respectively. In ICM patients, CV in areas with no visible fibrosis was 0.81 m/s (95%CI: 0.59-1.12 m/s). For each 25% increase in normalized LGE intensity CV decreased by 1.34-fold (95%CI: 1.25-1.43). Dense scar areas have on average 1.97-2.66-fold slower CV compared to areas without dense scar. Ablation lesions that terminated VTs were localized in areas of slow conduction on CV maps. Conclusions - CV is inversely associated with LGE-CMR fibrosis density in patients with ICM. Non-invasive derivation of CV maps from LGE-CMR is feasible. Integration of non-invasive CV maps with EAM during substrate mapping has the potential to improve procedural planning and outcomes.