Effect of gender on atrial electrophysiologic changes induced by rapid atrial pacing and elevation of atrial pressure

Introduction: The incidence of atrial fibrillation is greater in men than i n women, but the reasons for this gender difference are unclear. The purpos e of this study was to evaluate the effects of gender on the atrial electro physiologic effects of rapid atrial pacing and an increase in atrial pressu re. Methods and Results: Right atrial pressure and effective refractory period (ERP) were measured during sinus rhythm and during atrial and simultaneous AV pacing at a cycle length of 300 msec in 10 premenopausal women, 11 postm enopausal women, and 24 men. The postmenopausal women were significantly ol der than the premenopausal women (61 +/-8 years vs 34 +/- 10 years; P<0.01) . During sinus rhythm, mean atrial ERP in premenopausal women was shorter ( 211<plus/minus>19 msec) than in postmenopausal women and age-matched men (2 42 +/- 18 msec and 246 +/- 34 msec, respectively; P<0.05). Atrial ERPs in a ll patients shortened significantly during atrial and simultaneous AV pacin g. However, the degree of shortening during atrial pacing (43<plus/minus>8 msec vs 70 +/- 20 msec and 74 +/- 21 msec; P<0.05) and during simultaneous AV pacing (48<plus/minus>16 msec vs 91 +/- 27 msec and 84 +/- 26 msec; P<0. 05) was significantly less in premenopausal women than in postmenopausal wo men or age-matched men. Conclusion: The results of this study demonstrate a significant gender diff erence in atrial electrophysiologic changes in response to rapid atrial pac ing and an increase in atrial pressure. The effect of menopause on the obse rved changes suggests that the gender differences may be mediated by the ef fects of estrogen on atrial electrophysiologic properties.