Atrial fibrillation storms.

Evolving pacemaker and device technology now allows the onset pattern of arrhythmias to be identified. It is recognised that some cardiac arrhythmias have a circadian pattern of onset and that ventricular arrhythmias can occur in clusters of electrical storms. The long-term follow-up of patients with an atrial defibrillator suggests that in some patients persistent atrial fibrillation recurrences are not random, but can occur in clusters of 'atrial fibrillation storms'. A case report is used to demonstrate this newly recognised phenomenon.