Prevalence of interatrial block in a general population of elderly people

Interatrial block (IAB: P wave > or = 110 ms) is highly prevalent in people > or =65 years old living in a community.

We investigated 720 consecutive people age > or =65 years old, from the general population, with the intention of evaluating the prevalence of IAB in their electrocardiogram. After excluding 42 people with atrial fibrillation and atrial flutter (5%) or having a permanent pacemaker (0,83%), we evaluated the electrocardiograms of the remaining 678 people with sinus rhythm.

We identified 400 (59%) persons with IAB with a similar distribution between men (58.5%) and women (59.4%). IAB was also identified in 347 from a total of 570 hypertensive people (60,9%) and only in 53 out of 108 (49.1%) nonhypertensive people (P = 0.015).

The surprisingly large prevalence of the IAB in the general older population emphasizes the importance of the early recognition of this abnormality from the surface 12-lead electrocardiogram.