Page 91 - Simplicity is Key in CRT

ABSTRACT
Background Delayed left ventricular (LV) lateral wall (LVLW) activation is considered the electrical substrate that characterizes patients suitable for cardiac resynchronization therapy (CRT). Although typically associated with left bundle-branch block, delayed LVLW activation may also be present in patients with non-specific intra-ventricular conduction delay (IVCD). We assessed LVLW activation in CRT candidates with IVCD using coronary venous electro- anatomic mapping (EAM), and investigated whether QRS characteristics on the ECG can identify delayed LVLW activation.
Methods Twenty-three consecutive CRT candidates with IVCD underwent intra-procedural coronary venous EAM using EnSite NavX. QRS morphology, -duration, -fragmentation, -axis deviation, and left anterior/posterior fascicular block were assessed on baseline 12-lead ECGs.
Results Delayed LVLW activation (activation time>75% of QRS duration) occurred in 12/23 patients. In these patients, the latest activated region was consistently located on the basal lateral wall. QRS duration and prevalence of QRS fragmentation, left/right axis deviation, and left anterior/posterior fascicular block did not differ between patients with and without delayed LVLW activation.
Conclusion Coronary venous EAM can be used at the time of CRT implantation to determine the presence of delayed LVLW activation in patients with IVCD. Delayed LVLW activation is present in over 50% of patients with IVCD. QRS characteristics on the ECG seem unable to identify delayed LVLW activation in this subgroup of patients.
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