CMR for CRT implantation?

The implantation technique for cardiac resynchronization therapy (CRT) has remained virtually unchanged since it was first undertaken by Daniel Gras in 1994. As in randomized, controlled trials, most implanters adopt a lateral or posterolateral left ventricular (LV) lead position, assessed using intra-operative fluoroscopy. It is apparent, however, that even when the LV lead is deployed in fluoroscopically ‘optimal’ LV pacing positions (lateral or posterolateral), the response to CRT is variable. The ‘non-responder’ rate in CRT is said to be around 30%, depending on the criteria used to define response.