The interventricular conduction delays guide best cardiac resynchronization therapy: A tailored-patient approach to perform a CRT through Conduction System Pacing.

Evaluation of conduction intervals to predict success of resynchronization in biventricular pacing(BiVP) or Conduction System Pacing(CSP) is not spread in clinical practice. A right ventricle-to-left ventricle intrinsic conduction interval (RVs-LVs) > 70 ms or prolonged RVpaced - LVs(RVp-LVs)interval can predict Cardiac Resynchronization Therapy (CRT)response.This paper describes a case of cardiac resynchronization guided by spontaneous and paced interventricular conduction delays (IVCD) obtained in BiVP that led to changing intraoperative approach. A strategy for cardiac resynchronization based on the CSP/BiVP approach according to the IVCD could represent a viable and reliable solution to obtain a narrow paced QRS and to improve the CRT response.