Characterization of ventricular activation pattern and acute hemodynamics during multipoint left ventricular pacing

BACKGROUND Muttipoint left ventricular (LV) pacing (MultiPoint Pacing [MPP], St Jude Medical, Sylmar, CA) in a single coronary sinus branch has been introduced as a novel means of cardiac resynchronization therapy (CRT). It is speculated that MPP improves LV function by capturing a larger LV tissue area, resulting in uniform wavefront propagation throughout the ventricles, in comparison to conventional biventricular pacing (BIV). OBJECTIVE The purpose of this study was to evaluate MPP by means of contact mapping and hemodynamic measures to understand the underlying mechanisms and effects. METHODS Ten patients with non ischemic cardiomyopathy (mean age 69 +/- 9 years; 6 men (60%); New York Heart Association heart failure class II or III; QRS duration 173 +/- 20 ms; LV ejection fraction 27% +/- 5%) received a CRT-defibrillator capable of MPP. After the implantation procedure, an acute pacing protocol was implemented, including 2 BIV and up to 9 MPP interventions. In all pacing interventions, LV electrical activation patterns and hemodynamics (dP/dtmax) were evaluated, and for each patient, both the resulting measures were compared between MPP and BIV interventions. RESULTS Compared with BIV, MPP resulted in an increase in LV dP/dtmax (30% +/- 13% vs 25% +/- 11%; P = .041), a reduction in QRS duration (22% +/- 11% vs 11% +/- 11%; P = .01), and a decrease in total endocardial activation time (25% +/- 15% vs 10% +/- 20%; P = .01). MPP resulted in a larger capture of LV mass during the first 25 ms (35% +/- 22% vs 16% +/- 8%; P = .005) and during the first 50 ms (78% +/- 27% vs 60 +/- 23%; P = .03) of pacing, suggesting a quicker wavefront propagation throughout the left ventricle. CONCLUSION In this acute study, MPP in CRT improved both endocardiat and surface electrical parameters and hemodynamics in comparison with BIV.