I think ARNA trades up to $5-6 going into ADCOM and I believe the days prior to ADCOM will be highly volatile which everyone hedging their bets (I doubt many hold all their position going into ADCOM). Look for a nice run up again, but a sell off just prior.
As for the CV ADCOM, I feel a lot of the discussion was positive to ARNA's favor and potentially negative to VVUS (see VVUS AH shares sinking). I do believe the cardio trials will be required, but post-approval. I really can't see FDA dragging them around again.
ARNA is safe either way as they already have plenty of cardio safety data.