Atrial fibrillation in the elderly

Atrial fibrillation (AF) is the most frequent arrhythmia. Due to population aging, AF is a growing epidemic and its importance will continue to increase in the next decades. Although the prevalence of AF is high in advanced age, the number of subjects with predisposing factors for AF is even higher. Most of these factors increase the risk of atrial fibrosis, an important component of atrial arrhythmia mechanisms. In fact, the new techniques to detect atrial fibrosis are showing the strong association between atrial fibrosis and AF risk. Regarding predisposing factors for AF, interatrial block (IAB) seems to be a key factor. The diagnosis of IAB is easy to perform using the surface ECG. It is partial when the P wave duration is ≥ 120 ms, and advanced if furthermore the P wave presents a biphasic pattern in II, III and VF. IAB is very frequent in the elderly and, particularly in the case of the advanced type, is associated with AF, and AF recurrences. This association has been recently named Bayés syndrome. Moreover, IAB increases the risk of stroke, and seems to be associated with dementia. The anticoagulation in elderly patients at high risk of AF without documented arrhythmias is an open issue, but some data presented in this special number seem to support this hypothesis.  In fact, the association of IAB with the incidence of AF has been confirmed in different settings, including general population, centenarians, patients with previous AF, after cavotricuspid isthmus ablation, patients with high CHADS2 score, patients with structural heart disease, heart failure, and Chagas cardiomyopathy. In most cases, the risk was higher in those patients with advanced IAB. Although the reasons for this association are still not clear, atrial remodeling due to delayed and abnormal left atrium activation, especially in case of advanced IAB, is probably the key factor in the chain of events that lead to atrial fibrosis. This delayed activation produces an abnormal