Optimization of cardiac resynchronization therapy.

Cardiac resynchronization is now an accepted and widespread therapy for patients with left ventricular (LV) systolic dysfunction. However, there are still a significant number of patients that do not appear to gain benefit, and this is currently the focus of a great deal of research. Contemporary resynchronization devices allow manipulation of both atrioventricular (AV) and ventricular-to-ventricular (VV) delays and there is evidence that optimization of these delays has a positive effect on hemodynamics. However, there are many ways that optimization can be performed and there is little consensus on how, if at all, it should be incorporated into clinical practice.