I river an A after my 2nd barrel got called

[Hosehound25]

Villain is 28/22/3 (159) and seems like a competent player. I decided this was a good time for a 2nd barrel given the turn gave me some more outs if I get called. What to do on the river given villain's line?

Full Tilt Poker
No Limit Hold'em Cash Game
$0.50/$1.00 Blinds
6 Players - (LegoPoker Hand History Converter)

SB: $148.75
BB: $84.30
UTG: $125.85
<u>Hero (MP): $104.90</u>
CO: $52.25
<u>BTN: 152.70</u>

Preflop: Hero is dealt A[img]/images/graemlins/spade.gif[/img] Q[img]/images/graemlins/heart.gif[/img] (6 Players)
UTG calls $1.00, Hero raises to $4.00, CO folds, BTN calls $4.00, SB folds, BB folds, UTG folds

Flop: ($10.50) 6[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/diamond.gif[/img] 9[img]/images/graemlins/spade.gif[/img] (2 Players)
Hero bets $8.00, BTN calls $8.00

Turn: ($26.50) 3[img]/images/graemlins/spade.gif[/img] (2 Players)
Hero bets $20.00, BTN calls $20.00

River: ($66.50) A[img]/images/graemlins/diamond.gif[/img] (2 Players)
Hero???