Described herein are devices, systems and methods for cutting tissue in a patient. In some embodiments, a tissue modification region of a device includes a pair of flexible elongate cutting members extending along the length of the tissue modification region. Each elongate cutting member may be configured to cut a discrete trough into tissue to a depth that is greater than the thickness of the cutting member. In some embodiments, the device includes a spacer. The spacer may be sized and configured to operate in one of two modes. A first mode, in which the spacer is coupled to the cutting members such that it holds a portion of each of the two cutting members a distance from one another, and a second mode, in which at least a portion of the spacer is moved away from a cutting member to allow the cutting members to cut further into tissue.