Utility of Late Iodine Enhancement computed tomography with image subtraction in the evaluation of Cardiac Resynchronization Therapy response (ULIE-CRT study)

Introduction Thirty percent of patients fail to respond to cardiac resynchronization therapy (CRT). The evaluation of left ventricular (LV) dyssynchrony, myocardial scar, and coronary venous anatomy by image subtraction in Late Iodine Enhancement Computed Tomography (LIE-CT) has the potential to comprehensively characterize non- responders. Purpose To assess the feasibility and the utility of image subtraction in LIE-CT in CRT patients and compare findings between responders and non-responders. Methods Monocentric prospective study of CRT patients at least 6 months after implantation who underwent post-procedural CT between March and October 2018. CRT-responders were defined as patients with an absolute increase in LV ejection fraction > 5 %. CT-derived residual global and segmental dyssynchrony metrics, extent and location of myocardial scar, and position of LV lead relative to scar and segment of latest mechanical contraction were analyzed. Results Among the 29 patients (mean age 71 ± 12 years; 72% men), 18 were responders (62%). All CT metrics evaluating residual dyssynchrony such as wall motion index and wall thickness index were worse in non- responders (P  Fig. 1 ). Conclusion Image subtraction in LIE-CT in patients who had CRT is feasible and allows better characterization of CRT-non-responders, who have a greater amount of residual dyssynchrony than responders. Distribution of fibrosis in relation to the LV lead and presence of alternative venous branches may help patient management.