Figure 6

Tissue tracking (TT) preoperatively ( left ) and after implantation of CRT device ( right ), at best VV-interval (sequential pacing LV lead 20 ms before RV lead in this patient), showing improved systolic function, i.e. longitudinal motion. TT is a fast non-invasive method to study changes in systolic function fairly close related with changes in SMV (r = 0.80, p < 0.001).