A 38-year-old man with a history of migraine headaches with aura and one episode of ischemic stroke was found to have a patent foramen ovale (PFO). After percutaneous closure with the nickel-containing Amplatzer PFO occluder, the patient developed pericarditis, atrial fibrillation, and increased migraine headaches with aura that abated with oral prednisone. He tested positive for nickel hypersensitivity, which we conclude is the likely etiology of his pericarditis.