KA from first position

[mab_nyc69]

online tourn....down to 1200 from 6200 (pokerstar sunday million).
- blinds 800 / 1600
- i have 50,000 chips (400 out of 1200)

I raise to 6000 UTG with KA unsuited

- fold around...two away from button makes it 20k (he has about 50k in chips as well)

- i call.....miss my flop....shove anyway...never hit
- he shows KK

I know i could have just shoved pre-flop even though same outcome

- at that point...do i fold to the reraise or play cointoss?

- with 29k left in chips....should i have just check folded after the flop once i didnt hit?

- I was thinking maybe i get lucky and get him off of a low pair, KA, QA, etc.

- was this a donk play?