RESUMEN
BACKGROUND: The prevalence of atrial fibrillation (AF) has been reported to increase with advancing age. Histologic studies in AF have demonstrated that the percentage of fibrosis and degenerative changes in the atrial muscle increase significantly with age. HYPOTHESIS: This study was undertaken to assess the influence of advancing age on atrial endocardial electrograms recorded during sinus rhythm in patients with paroxysmal atrial fibrillation (PAF), which had not been assessed previously. METHODS: Right atrial endocardial catheter mapping during sinus rhythm was performed in 111 patients with PAF to evaluate the influence of advancing age on atrial endocardial electrograms. The bipolar electrograms were recorded at 12 sites in the right atrium, and an abnormal atrial electrogram was defined as lasting > or = 100 ms, and/or showing eight or more fragmented deflections. RESULTS: In all, 1,332 right atrial endocardial electrograms were assessed and measured quantitatively. The number of abnormal atrial electrograms in patients with PAF showed a significantly positive correlation with age (r = 0.34; p < 0.0005). Patients aged > 60 years had a significantly greater mean number of abnormal electrograms (2.58 +/- 2.05) than those aged < 60 years (1.43 +/- 2.03; p < 0.004). The longest duration (r = 0.35; p < 0.0005) and the maximal number of fragmented deflections (r = 0.29; p < 0.005) of atrial electrograms among the 12 right atrial sites also showed a significantly positive correlation with age. CONCLUSIONS: Aging alters the electrophysiologic properties of the atrial muscle in patients with PAF. Elderly patients have a significantly greater abnormality of atrial endocardial electrograms than do younger ones. There is a progressive increment in the extension of altered atrial muscle with advancing age in patients with PAF.