The invention includes an implantable medical electrical lead for electrical stimulation of body tissue that includes at least one modifiable portion that exhibits a first configuration when exposed to a first temperature and a second configuration when exposed to a second temperature, wherein the second configuration of the modifiable portion exhibits a greater resistance to movement of the lead within the body tissue than does the first configuration, and the second temperature is higher than the first temperature; and at least one electrode configured to provide electrical stimulation of body tissue, wherein the lead has a proximal end and a distal end. Systems including leads of the invention and methods of implanting leads of the invention are also included.