17-year-old presents to emergency room with “irregularly irregular” rhythm

Case

Hello, I’m calling from the ER at the adult hospital across the street. I have a 17-year old male who came in for palpitations. He says that he first noted them two days ago when he was hanging out with his friends. They were playing basketball and he says he felt fine at that time but went to cool off with a drink at the local convenience store. I asked about energy drinks, but he says he just had one of those cold slush drinks. Soon after that he felt his heart beating funny. He went to bed that night and when he woke up he still had the same feeling but less pronounced. He’s had school for the past few days so it wasn’t bothersome enough to skip school but today he says that he’s feeling more tired and has less energy than usual so his father brought him into the ER. When I auscultate, I hear an irregularly, irregular rhythm so I got an ECG. The ECG says that he is in atrial fibrillation! I tend to see a lot of this in our ER and it sure does look and sound like A-fib; but in a 17-year old? Should I start him on a diltiazem drip? Do I need to put him on anticoagulation?