What will be the best course of action for this stitch at 1 year post-op? (Photos)

Thanks for your inquiry, this could be a permanent suture that goes around your areola, please discuss with your surgeon and do not try to force it out on your own, best of luck. 

At this point of your recovery all the sutures should have dissolved.  If your doctor used a permanent suture, it could be trying to work it's way out.  See your plastic surgeon to asses your condition. If you are not having any other problems, it should not be an issue to worry about.