Estimation of the Optimal VV Delay by an IEGM‐Based Method in Cardiac Resynchronization Therapy

Abstract

Determination of the optimal interventricular (VV) delay in cardiac resynchronization therapy currently relies on costly, time-consuming echocardiographic (ECHO) methods. This study evaluated the performance of a new intracardiac electrogram (IEGM)-based VV method compared to the aortic velocity time integral (AVTI) method of VV delay optimization. The study included two patient groups. Eleven patients enrolled by a single center in the Rhythm II ICD trial underwent prospective comparisons of the AVTI at the VV interval determined by the IEGM VV method versus the maximum AVTI at the echocardiographically determined optimal VV delay. In 61 patients enrolled in the RHYTHM VV trial, the same testing methods were compared retrospectively. In the prospective study, the maximum AVTI by the ECHO-based method (24.3 +/- 7.9 cm), was closely correlated with maximum AVTI by the IEGM-based method (23.9 +/- 7.9 cm; concordance correlation coefficient = 0.99; 95% confidence, lower limit of 98%. Likewise, in the retrospective analysis, the ECHO-determined maximum AVTI (22.1 +/- 8.2 cm) was similar to that determined by the IEGM-based method (20.9 +/- 8.3 cm; concordance correlation coefficient = 0.98; 95% confidence, lower limit of 97%).

A Real‐Time Three‐Dimensional Echocardiographic Validation of an Intracardiac Electrogram‐Based Method for Optimizing Cardiac Resynchronization Therapy

“…A new validated tool (QuickOpt(tm), St. Jude Medical, Sylmar, CA, USA) based on intracardiac electrograms (IEGM) has been recently proposed to identify the individual optimal AV/PV and VV delays during device follow‐up 7,8 …”

“…This device‐based optimization system was previously validated against aortic velocity time integral (VTI) measurements, with a >96% correlation coefficient for AV, PV, and VV delays 8 …”

Comparison of P wave durations as assessed with the bipolar and unipolar atrial intracardiac electrograms: Applicability to QuickOpt™

“…The IEGM-CRT clinical study in over fifty subjects [1] demonstrated that the echo-Doppler derived aortic velocity integral (AVTI) values at the QuickOptpredicted AV, PV, and VV delays were linearly correlated with maximum AVTI, with Concordance Correlation Co-efficients (CCC) of 97.5%, 96.1% and 96.6% respectively. A retrospective analysis of data from SJM's RHYTHM study, where the VV intervals were optimized in sixty-one patients [2] also showed strong Concordance Correlation Co-efficient (CCC) =99%. Additional analysis of VV delays [3] was done retrospectively in the combined RHYTHM VV and IEGM-CRT patient cohorts.…”

Strategies for pacemaker programming in acute heart failure

“…Recently, automated programmer algorithms based on intracardiac electrograms (IEGM) have been developed to expedite this process and is currently available in some CRT devices. Two small studies showed that the IEGM method correlated closely with A-V and V-V optimization determined by Doppler measured aortic valve VTI [49,50]. The IEGM method also was found to result in a higher degree of LV resynchronization and greater improvement in LV ejection fraction based on real-time three-dimensional echocardiographic assessment [28].…”