One-third of patients undergoing open-heart surgery experience an episode of atrial fibrillation on the second or third day after surgery. The findings presented in this book indicates that postoperative atrial fibrillation is a risk factor for late arrhythmia and late cardiovascular death. Postoperative atrial fibrillation is not correlated to infammation in the presented studies, and surgical ablation seems to preserve atrial contractile function.