HMGB1 and Paroxysmal atrial fibrillation: Previous reports have demonstrated that the serum HMGB1 concentration is increased in patients with paroxysmal AF or persistent AF compared with those with normal sinus rhythm (SRs).[18] A HMGB1 gene polymorphism had been found to be associated with the risk of postoperative AF after coronary artery bypass graft (CABG) surgery.[19] HMGB1 is a protein that is associated with inflammation and thrombi in other diseases.