This disclosure describes implantable medical leads that include a lead body and an electrode. A width of the electrode as measured along a longitudinal direction of the lead varies about the perimeter of the lead. The uneven width of the electrode may bias a stimulation field in a particular direction, e.g., a radial or transverse direction relative to the longitudinal axis of the lead. Electrodes with an uneven width may be useful for controlling the direction of propagation of the stimulation field in order to, for example, avoid phrenic nerve stimulation during LV pacing or neck muscle stimulation during vagal neurostimulation.