Key result
CRT optimization yields effective VV delays shorter than programmed LV preactivation in ~46% of patients.
Why the study?
Does the effective VV delay differ from the programmed VV delay during standard CRT optimization in patients with heart failure and LBBB?
Observational (n=33)
Does the effective VV delay differ from the programmed VV delay during standard CRT optimization in patients with heart failure and LBBB?
In CRT patients with LBBB without total AV block, the effective VV delay is often shorter than the programmed VV delay, particularly during LV preactivation by 40 ms or more.
Effective VV delay often mismatches programmed settings in CRT; hypothesis-generating for outcome impact of individualized optimization in LBBB HF.
BACKGROUND: In cardiac resynchronization therapy (CRT) devices, the interventricular (VV) delay denotes the time interval between left (LV) and right ventricular (RV) pacing. This study aimed to determine the proportion of patients in whom the effective VV delay (VVeff , delay between LV and RV depolarization, being induced either by pacing or intrinsic conduction) is different from the programmed VV delay during a standard VV delay optimization procedure. METHODS: Thirty-three patients with heart failure and left bundle branch block configuration without total atrioventricular (AV) block receiving CRT were prospectively included. VVeff was calculated from intrinsic AV intervals, programmed optimal AV delay, and programming system. Intrinsic AV intervals were measured on intracardiac electrograms. The optimal AV and VV delays were determined by highest increase in maximum rate of LV pressure rise (dP/dtmax ). VV delays of 20-80 ms LV and RV preactivation were tested. RESULTS: Calculated maximum possible VVeff was shorter than 80 ms LV preactivation in up to 46% of patients and shorter than 40 ms LV preactivation in up to 3% of the patients. These proportions were 6% and 0% during 80 and 40 ms RV preactivation, respectively. CONCLUSIONS: In CRT patients with left bundle branch block without total AV block, the effective VV delay is shorter than the programmed VV delay during a standard optimization procedure in approximately half of the patients and this phenomenon is encountered predominantly during LV preactivation by 40 ms or more. Calculation of the individual maximum VVeff in advance can shorten the VV delay optimization procedure.
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Bogaard et al. (2013) conducted an observational in Heart failure and left bundle branch block without total AV block receiving CRT (n=33). Standard VV delay optimization procedure was evaluated on Calculated maximum possible effective VV delay shorter than 80 ms LV preactivation. During standard CRT optimization in patients with heart failure and LBBB, the effective VV delay was shorter than the programmed 80 ms LV preactivation in up to 46% of patients.
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