Different regions of latest electrical activation during left bundle-branch block and right ventricular pacing in cardiac resynchronization therapy patients determined by coronary venous electro-anatomic mapping

Masih Mafi Rad*, Yuri Blaauw, Trang Dinh, Laurent Pison, Harry J. Crijns, Frits W. Prinzen, Kevin Vernooy

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Aim Current targeted left ventricular (LV) lead placement strategy is directed at the latest activated region during intrinsic activation. However, cardiac resynchronization therapy (CRT) is most commonly applied by simultaneous LV and right ventricular (RV) pacing without contribution from intrinsic conduction. Therefore, targeting the LV lead to the latest activated region during RV pacing might be more appropriate. We investigated the difference in LV electrical activation sequence between left bundle-branch block (LBBB) and RV apex (RVA) pacing using coronary venous electro-anatomic mapping (EAM). Methods and resultsTwenty consecutive CRT candidates with LBBB underwent intra-procedural coronary venous EAM during intrinsic activation and RVA pacing using EnSite NavX. Left ventricular lead placement was aimed at the latest activated region during LBBB according to current recommendations. In all patients, LBBB was associated with a circumferential LV activation pattern, whereas RVA pacing resulted in activation from the apex of the heart to the base. In 10 of 20 patients, RVA pacing shifted the latest activated region relative to LBBB. In 18 of 20 patients, the LV lead was successfully positioned in the latest activated region during LBBB. For the whole study population, LV lead electrical delay, expressed as percentage of QRS duration, was significantly shorter during RVA pacing than during LBBB (72 13 vs. 82 +/- 5%, P = 0.035). Conclusion

Right ventricular apex pacing alters LV electrical activation pattern in CRT patients with LBBB, and shifts the latest activated region in a significant proportion of these patients. These findings warrant reconsideration of the current practice of LV lead targeting for CRT.

Original languageEnglish
Pages (from-to)1214-1222
JournalEuropean journal of heart failure
Issue number11
Publication statusPublished - Nov 2014


  • Cardiac resynchronization therapy
  • Left bundle-branch block
  • Right ventricular pacing
  • Left ventricular electrical activation
  • Left ventricular lead placement
  • Electro-anatomic mapping

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