I Have 20 To 25% Ejetion Fraction. I Have No

I have 20 to 25% Ejetion fraction. I have no plugged arteries, or pacemaker, etc. This was discovered May of 2016. Pills have been regulated, do get lightheaded, get up to fast, etc. Have falled down because of weakness in the leggs, 2 or 3 times during this time. They have mentioned a defibulater, but, I am not sure I want one. About how long would I have to live before I have a heartattack? I forgot to say I'm 66yr. old women. I would like to hear from a cardiologist specialist.