LV cathode position in CRT recipients: How can we benefit from CMR?

Background: Left ventricular lead positioning represents a key step in CRT optimization. However, evidence for its guidance based on specific topographical factors and related imaging techniques is sparse. Objective: To analyze reverse remodeling (RR) and clinical events in CRT recipients based on LV cathode (LVC) position relative to latest mechanical activation (LMA) and scar as determined by cardiac magnetic resonance (CMR). Methods: This is a retrospective single-center study of 68 consecutive Q-LV-guided CRT-D and CRT-P recipients. Through CMR-based 3D reconstructions overlayed on fluoroscopy images, LVCs were stratified as concordant, adjacent, or discordant to LMA (3 segments with latest and greatest radial strain) and scar (segments with >50% scar transmurality). The primary endpoint of RR (expressed as percentage ESV change) and secondary composite endpoint of HF hospitalizations, LVAD/heart transplant, or cardiovascular death were compared across categories. Results: LVC proximity to LMA was associated with a progressive increase in RR (percentage ESV change: concordant-47.0 +/- 5.9%, adjacent-31.4 +/- 3.1%, discordant +0.4 +/- 3.7%), while proximity to scar was associated with sharply decreasing RR (concordant +10.7 +/- 12.9%, adjacent +0.3 +/- 5.3%, discordant-31.3 +/- 4.4%, no scar-35.4 +/- 4.8%). 4 integrated classes of LVC position demonstrated a significant positive RR gradient the more optimal the category (class I-47.0 +/- 5.9%, class II-34.9 +/- 2.8%, class III-5.5 +/- 4.3%, class IV + 3.4 +/- 5.2%). Freedom from composite secondary endpoint of HF hospitalization, LVAD/heart transplant, or cardiovascular death confirmed these trends demonstrating significant differences across both integrated as well as individual LMA and scar categories. Conclusion: Integrated CMR-determined LVC position relative to LMA and scar stratifies response to CRT.