Suggest Treatment For Itchy Keloid Scar

I had a Medtronic BIV/ICD pacemaker implanted 2005; replacements 2008, 2011. I have a (keloid) scar that is still very irritating and itchy. I've tried Vitamin E, cortosoine creams, Mederma. I put cloth diapers, gauze, shoulder pads, etc. across it...doesn't really help. It started out as a thin horizontal scar but towards the end, away from my armpit, it spreads vertically up and down. The cardiologist and the plastic surgeon [who revised the pacemaker site in 2012] say they've never seen anything like it. Oh, I'm very thin [5'5", 127 lbs] if that matters. Are there any long-lasting ways to soothe the area?