Relation of Age and Sex to Atrial Electrophysiological Properties in Patients with No History of Atrial Fibrillation

Abstract

Although atrial fibrillation is a common arrhythmia, especially in elderly men, little is known about age related changes in atrial electrophysiological properties or gender differences. The aim of this study was to analyze the effects of aging on vulnerability to atrial fibrillation and assessed gender differences in those age related changes. An electrophysiological study was performed on 73 patients with no history of atrial fibrillation, structural heart disease, or conditions with potential effects on cardiac hemodynamic or electrophysiological function, including 25 women (mean age 49 +/- 18 years; range 12-84 years). The following atrial excitability parameters were assessed: spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (A2/A1 x 100), effective refractory period, wavelength index (effective refractory period/A2), and inducibility of atrial fibrillation. There were no significant differences in percent maximum atrial fragmentation (143 +/- 28 vs 142 +/- 35%), effective refractory period (241 +/- 39 vs 238 +/- 50 ms), wavelength index (2.9 +/- 0.8 vs 3.1 +/- 0.9), induction of atrial fibrillation (10 [21%] vs 7 [28%]), or age (50 +/- 17 vs 49 +/- 20 years) between men and women. Age was not statistically different between those patients with and without induction of atrial fibrillation in men (48 +/- 14 vs 50 +/- 18 years) and women (48 +/- 18 vs 49 +/- 21 years). Percent maximum atrial fragmentation and effective refractory period were directly correlated with age in men (r = 0.35, P = 0.01; r = 0.46, P< 0.001, respectively) and women (r = 0.42, P = 0.04; r = 0.45, P = 0.02, respectively), though wavelength index did not correlate with age in men (r = -0.04) or women (r = -0.04) with no history of atrial fibrillation. Considering these findings, the authors conclude that the mechanism triggering atrial fibrillation may be different between older and younger patients with atrial fibrillation, because younger patients who have no marked substrate for atrial fibrillation may need many trigger beats to induce atrial fibrillation.

ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation

“…This, coupled with the shorter wavelengths of reentrant impulses, increases the likelihood that AF will develop. 134,135 Nonuniform alterations of refractoriness and conduction throughout the atria may provide a milieu for the maintenance of AF. However, the degree to which changes in the atrial architecture contribute to the initiation and maintenance of AF is not known.…”

Central Sleep-disordered Breathing Predicts Incident Atrial Fibrillation in Older Men

“…Interactions of age as a continuous variable: CAI >5, P = 0.04; CSA-CSR, P = 0. the effects of advanced age and SDB may be multiplicative. For example, the pathophysiologic insults of SDB, including intermittent hypoxia, autonomic imbalance, and intrathoracic pressure swings, may have more pronounced effects on atrial arrhythmogenesis when superimposed on the aged heart, which has an electrophysiologic substrate different from that of younger individuals (47)(48)(49)(50)(51). Enhanced impulse generation due to increased automaticity, triggered activity, and reentrant circuits within the atria and pulmonary veins are considered to be responsible for AF initiation and maintenance in the elderly and at a specific age threshold may be more likely to occur as a pathophysiologic response to SDB-induced physiologic stress (48,50,52).…”

Electrophysiologic and electroanatomic changes in the human atrium associated with age

“…There have been conflicting results regarding the effect of aging on atrial ERP with some studies showing an increase (12,13), while others have suggested no change (14). Studies to date have been limited with restriction to single RA sites only.…”