Though the OP stated "arctic 7" I couldn't locate that at their website. But for their others (original, 2, 3, 5) it had this stated:
"Negligible electrical conductivity.
Arctic Silver was formulated to conduct heat, not electricity. It is only electrically conductive in a thin layer under extreme compression."
"While much safer than electrically conductive silver and copper greases, Arctic Silver should be kept away from electrical traces, pins, and leads. The compound is slightly capacitive and could potentially cause problems if it bridged two close-proximity electrical paths.)"
While this may work well for many applications, if I need 100% electrical isolation I would not want to use this myself. Amps to heatsinks: Sure, but anything isolated with mica.. not sure.
Again, I've not used it myself and it may work well, but I was concerned that could lead to a problem for the OP. Just throwing out ideas.