A rearview mirror reflective element assembly includes a mirror reflective element, a heater pad, and a back plate. The heater pad includes a heater pad substrate having a plurality of electrically conductive traces established thereat, with the electrically conductive traces including (i) a heating trace that, when powered, heats the heater pad substrate and the mirror reflective element, and (ii) an accessory trace that, when powered, controls an accessory of the mirror reflective element assembly. The electrically conductive traces may include electro-optic control traces that, when electrically powered, darken the mirror reflective element. The heater pad is disposed between the mirror reflective element and the back plate. The accessory trace, when powered, controls a blind zone indicator that is disposed at the rear of the mirror reflective element and that is viewable, when powered, through the mirror reflective element.