A filar includes an inner conductive core that is formed of a low-resistivity material such as silver having a resistivity of less than 20 μΩ per centimeter. A conductive coil is provided around the core to form a filar. This coil is formed of a biocompatible alloy or super alloy having an ultimate tensile strength (UTS) of between 150 kilo pounds per square inch (ksi) and 280 ksi at room temperature. Examples of such alloys include CoCrMo, CoFeCrMo, and CoFeNiCrMo. In one specific embodiment, the alloy is MP35N (CoNiCrMo), which may be low-titanium (“low-ti”) MP35N. One or more such filars may be included within a wire. This wire may be carried by an implantable medical apparatus such as a lead, lead extension, or catheter. The wire may electrically couple elements such as connector electrodes to conducting electrodes or sensors.