Endothelial function at baseline and follow-up (responders in white bars and non-responders in black). Endothelial function at baseline and follow-up (responders in white bars and non-responders in black). (A) Changes in flow-mediated dilation (FMD) following cardiac resynchronisation therapy (CRT) in responders, there were no significant differences at 6 or 12 months. (B) Changes in nitroglycerine-mediated dilation (NMD) following CRT in responders, there were no significant differences at 6 or 12 months. (C) Changes in flow-mediated dilation (FMD) following CRT in non-responders, there were no significant differences at 6 or 12 months. (D) Changes in nitroglycerine-mediated dilation (NMD) following CRT in non-responders, there were no significant differences at 6 or 12 months. David R Warriner et al. Open Heart 2016;3:e000391 ©2016 by British Cardiovascular Society