An intravascular implantable medical device includes a detachable tether arrangement. In one embodiment, the detachable tether arrangement comprises a tip assembly that includes a break-away joint and a tether portion, and may also include a connector and an extension portion connected to an end of an elongated intravascular implantable medical device. In this embodiment, the break-away joint is disposed between the extension portion and the tether portion. In some embodiments, the extension portion may comprise a housing or other arrangement that includes an antenna for transmitting and receiving data. In other embodiments, the extension portion may also include a lead for defibrillation, pacing, and/or sensing cardiac electrical activity. In certain embodiments, the tether arrangement is designed to be secured within a patient's vasculature with a vascular anchor either in the form of a separate anchor, such as a conventional stent, or by various integrated retention arrangements.