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.