Asynchronous myocardial contraction in heart failure is associated with poor prognosis. Recent studies have shown an acute and sustained hemodynamic improvement after biventricular pacing (BVP), reversal of LV-remodelling, an increased quality of life, a reduction of symptoms of heart failure, and an improvement of exercise tolerance [1–7].
The optimization of the AV delay in DDD pacemaker patients is generally recommended and is performed in clinical practice. A variety of invasive and non-invasive methods were assessed in the past [8–15]. Recent studies have shown that also in CRT patients, invasively (dP/dt) [16–19] and non-invasively measured hemodynamic parameters (stroke volume) [20, 21] are modified according to the programmed AV delay. A hemodynamically optimal AV delay can be defined.
Ismer's method of AV delay optimization  is validated for biventricular as well as right ventricular DDD pacing.
Tissue Doppler Imaging (TDI) is an evaluated tool in clinical practice to identify myocardial dyssynchrony. TDI (including strain and strain rate) imaging measures regional wall motion velocities and can accurately quantify regional left ventricular function .
Strain measures compression and distension of myocardial segments ("deformation imaging") and strain rate imaging expresses strain changes per time interval . TSI (Tissue Synchronization Imaging) utilizes color-coded time-to-peak tissue Doppler velocities and visualizes segments of dyssynchrony in real-time by superimposing these temporal motion data on 2D echo images. [26, 27].
These new techniques could potentially improve patient selection and guidance of implantation and programming of the devices for BVP. There is a variety of methods to determine dyssynchrony as summarized elsewhere .
There are no published data on the correlation of parameters of dyssynchrony and programming of the optimal AV interval. Aims of our study were therefore to investigate the influence of an optimized AV delay determined by the method of Ismer et al.  on dyssynchrony.