In some examples, an implantable medical device (IMD) that includes a pulse generator comprising a housing, electrodes, and circuitry configured to deliver cardiac pacing via the electrodes. The IMD may further include a lead including at least one of the electrodes, an elongate body, a fixation helix, and a connector segment. A width of the helix transverse to a longitudinal axis of the lead is greatest at a distal end of the helix. A proximal end of the elongate body may be connected to a distal end of the pulse generator, and the helix may be attached to a distal end of the elongate body. The pulse generator may include a first connector tab. A distal end of the connector segment may be configured to receive the proximal end of the elongate body and a proximal end of the connector segment may include at least one second connector member configured to engage the first connector tab.