An implantable medical electrical lead extending from a connector terminal thereof to a distal-most tip thereof, the connector terminal comprising a plurality of contacts (C1, C2, C3, C4) and a grip sleeve extending distally from the contacts, and the lead further comprising: first and second electrodes (E1, E2) both being spaced proximally from the distal-most tip and the second electrode being spaced distally from the first electrode; and first and second elongated conductors (190, 191) electrically isolated from one another, the first and second conductors coupling the first and second electrodes, respectively, to corresponding first and second contacts of the plurality of connector terminal contacts; and a fixation element located between the first and second electrodes, the fixation element comprising a wire wound into a tissue engaging helix, the helix extending around the outer surface of the lead and being terminated by a piercing distal tip of the wire, the piercing distal tip spaced laterally from the lead outer surface; and an elongated proximal outer insulation tube (110, 510) extending around the first and second elongated conductors between the connector terminal and the first electrode, the outer insulation tube comprising a proximal segment extending distally from the grip sleeve and a distal segment extending distally from the proximal segment, the distal segment having an overall length of at least 50.8 cm (20 inches), outer surfaces of each of the proximal and distal segments defining, at least in part, portions of the outer surface of the lead, the outer insulation tube transitioning from a first outer diameter along the proximal segment to a second, lesser outer diameter along the distal segment. first and second electrodes (E1, E2) both being spaced proximally from the distal-most tip and the second electrode being spaced distally from the first electrode; and first and second elongated conductors (190, 191) electrically isolated from one another, the first and second conductors coupling the first and second electrodes, respectively, to corresponding first and second contacts of the plurality of connector terminal contacts; and a fixation element located between the first and second electrodes, the fixation element comprising a wire wound into a tissue engaging helix, the helix extending around the outer surface of the lead and being terminated by a piercing distal tip of the wire, the piercing distal tip spaced laterally from the lead outer surface; and an elongated proximal outer insulation tube (110, 510) extending around the first and second elongated conductors between the connector terminal and the first electrode, the outer insulation tube comprising a proximal segment extending distally from the grip sleeve and a distal segment extending distally from the proximal segment, the distal segment having an overall length of at least 50.8 cm (20 inches), outer surfaces of each of the proximal and distal segments defining, at least in part, portions of the outer surface of the lead, the outer insulation tube transitioning from a first outer diameter along the proximal segment to a second, lesser outer diameter along the distal segment.