BACKGROUND
Cardiac resynchronization therapy (CRT) is a well-accepted therapy for
patients with heart failure (HF), left ventricular (LV) systolic
dysfunction, and QRS prolongation. Large, randomized trials have shown
improvement in symptoms, in LV structure and function, reduction in
hospitalizations, and decrease of mortality in patients treated with
CRT1,2. Unfortunately, a significant proportion of
patients do not respond to CRT and this is related to poorer
outcomes3. Suboptimal LV lead position and persistent
mechanical dyssynchrony, affecting 25-30% of patients despite
conventional biventricular pacing4, have been some of
the suggested reasons to explain the absence of response to CRT.
Multipoint LV pacing (MPP) through a quadripolar lead has been advocated
to enhance the likelihood of response to CRT by stimulating and
capturing a broader area of the LV. First studies with this new modality
of LV pacing have reported benefits in terms of acute hemodynamic
improvement, higher left ventricular ejection fraction (LVEF) and a
higher ability to reduce dyssynchrony in comparison with conventional
biventricular pacing5-8. Considering that LV
mechanical dyssynchrony and contractile function are important
determinants of long-term CRT benefit9,10, MPP could
offer advantages over conventional single LV site biventricular pacing.
It has been suggested that MPP would be especially useful for
non-responder patients to CRT11. Nevertheless, the
time necessary to evaluate the degree of response to CRT has not been
established and the optimal moment to activate MPP remains a challenging
issue. Whereas the strategy of activating MPP only in patients not
responding to conventional biventricular pacing have been advocated and
evaluated in randomized clinical trials, the possible advantages of the
activation of MPP early after the device implantation have been poorly
studied.
The objectives of this study were to prospectively assess the CRT
response rate at 6 months in patients implanted with a CRT-D device with
the MPP feature activated early after the implant.