P323Response to cardiac resynchronization therapy is determined by intrinsic electrical substrate rather than by its modification. (19th March 2018) - Strik, M; Ploux, S; Huntjens, P; Frontera, A; Eschalier, R; Dubois, R; Ritter, P; Klotz, N; Haissaguerre, M; Crijns, HGJM; Prinzen, F W; Bordachar, P