Whether noninvasive optimization of AV and VV delays improves the response to cardiac resynchronization therapy

Abstract

Background: Device optimization is not routinely performed in patients who underwent
cardiac resynchronization therapy (CRT) device implantation. Noninvasive optimization of
CRT devices by measurement of cardiac output (CO) can be used as a simple method to assess
ventricular systolic performance. The aim of this study was to assess whether optimization of
atrioventricular (AV) and interventricular (VV) delay can improve hemodynamic response to
CRT and whether this optimization should be performed for each patient individually.

Methods: Twenty patients with advanced heart failure New York Heart Association (NYHA)
class III/IV, left ventricular ejection fraction ≤ 35% and left bundle branch block (QRS ≥ 120 ms)
in sinus rhythm were evaluated from 24 h to 48 h after implantation of a CRT device by means
of impedance cardiography (ICG). CO was fi rst measured at each patient’s intrinsic rhythm.
Patients then underwent adjustments of AV and VV delay from 80 ms to 140 ms and from
–60 ms to +60 ms, respectively in 20 ms increment steps and CO at each setting was measured
by ICG. Both AV and VV delays were programmed according to the greatest improvement in
CO compared to intrinsic rhythm.

Results: There was a statistically signifi cant increase in CO measured at the intrinsic rhythm
compared to different AV delay by mean of 21% (3.8 ± 1.0 vs. 4.6 ± 0.1 L/min, p < 0.05).
Optimal AV/VV delays with left ventricle-preexcitation or simultaneous biventricular pacing
caused additional increased CO from intrinsic rhythm by mean of 32.6% (3.8 ± 1.0 vs. 5.04 ±
± 1.0 L/min, p < 0.05). Optimal AV/VV setting delays also resulted in improved hemodynamic
responses compared to VV factory setting delay.

Conclusions: Both AV and VV delay optimization should be performed in clinical practice.
Optimal AV delay improved outcome. However, combination of optimized AV/VV delays provided
the best hemodynamic response. Optimized AV/VV delays with left ventricle-preexcitation
or simultaneous biventricular pacing increased hemodynamic output compared to intrinsic
rhythm and VV factory setting delay.