IEGM based method for estimating optimal AV delay in cardiac resynchronization therapy

Abstract

Background: Huge intra-atrial conduction delay is common in HF patients due to mitral valve regurgitation and dilated left atrium. Normal AV or PV delay setting can cause patients to suffer from a similar symptom of pacemaker syndrome. Some clinical experience taught us programming AV or PV delay 30 ms to 60 ms after the end of P wave (or paced atrial depolarization) relieved patient’s symptom instantly and in the further follow-up. We formulated a simple relation using IEGM to estimate optimal AV delay based on the clinical observations. This study is to compare an IEGM based method against echo measured optimal AV delays. Methods: Nine patients had NYHA class III, LBBB, EF 35% implanted with SJM EPIC HF ICD. The device IEGM channels recorded the end of atrial depolarization (EAD), intrinsic RV and LV depolarization conducted from atria denoted as ARRV and ARLV. The predicted optimal AV or PV delay is simply the sum of the end of atrial depolarization and an add-on interval (d) which is 60 ms if EAD is less than 100 ms or 30 ms if EAD is greater than 100 ms. AV (or PV delay) needs to be less than both ARRV and ARLV. The echo E and A wave method tested AV delay at 50 ms, 300 ms (intrinsic conduction) and several AV delays with 30 ms resolution. Results: All RA leads were at RA appendage, RV leads at RV apical position and LV leads at mid lateral wall. The EAD was 70.0 ms 16 ms. The echo determined optimal AV delay was 119 ms 29 ms and the IEGM predicted AV delay was 130 ms 16 ms. The difference between these two methods was 22 ms 11 ms which was smaller than the resolution in common clinical testing. Conclusions: The simple IEGM based method for predicting optimal AV delays were reasonably close toecho determined optimalAV delays. Automated AV delay in devices may provide better CRT performance daily and will reduce the usage of echo measurement in CRT and therefore the cost. 208