Left ventricular lead placement in cardiac resynchronization therapy: Current data and potential explanations for the lack of benefit

The present article reviews the literature on image -guided cardiac resynchronization therapy (CRT) studies. Improved outcome to CRT has been associated with the placement of a left ventricular (LV) lead in the latest activated segment free from scar. The majority of randomized controlled trials investigating guided LV lead implantation did not show superiority over conventional implantation approaches. Several factors may contribute to this paradoxical observation, including inclusion criteria favoring patients with left bundle branch block who already respond well to conventional anatomical LV lead implantation, differences in activation wavefronts during simultaneous right ventricular and LV pacing, incorrect definition of target regions, and limitations in coronary venous anatomy that prevent access to target regions that are detected by imaging. It is imperative that exclusion of patients lacking access to target regions from these studies would lead to larger benefit of image -guided CRT.

Automated summary

This article reviews the literature on image-guided CRT studies. Improved outcome is associated with LV lead placement in the latest activated segment without scar. Most RCTs did not show superiority of guided implantation. Factors include patient selection, differences in activation wavefronts, incorrect target region definition, and limitations in coronary venous anatomy. Excluding patients without access to target regions may lead to greater benefit of image-guided CRT.