The influence of advancing age on the electrophysiological changes of the atrial muscle induced by programmed atrial stimulation.

The influence of advancing age on the electrophysiological changes of the atrial muscle induced by programmed atrial stimulation, such as fragmented atrial activity (FAA), interatrial conduction delay (ICD), and repetitive atrial firing (RAF), was investigated in 42 patients with neither documented episodes of paroxysmal atrial fibrillation nor sick sinus syndrome. The induction rates of FAA, ICD, and RAF were not affected by age. The zones of FAA, ICD and RAF, did not show any correlation with age. However, the longest coupling interval giving rise to FAA (longest CI-FAA) or ICD (longest CI-ICD) showed a significant correlation with age (longest CI-FAA; r = 0.428, p less than 0.01, longest CI-ICD; r = 0.398, p less than 0.01). Although the longest coupling interval giving rise to RAF did not show a direct correlation with age (r = 0.267), it was significantly longer in patients over 60 years of age than in those under 60 (p less than 0.05). These results suggest that aging affects the electrophysiological properties of the atrial muscle, which can help to explain why atrial fibrillation is seem more frequently in the elderly.