Influence of menstrual cycle on p wave dispersion.

Female gender is an independent risk factor for some types of arrhythmias. We sought to determine whether the menstrual cycle affects P wave dispersion, which is a predictor of atrial fibrillation. The study population consisted of 59 women in follicular phase (mean age, 29.3 ± 7.7 years) (group F) and 53 women in luteal phase (mean age, 28.1 ± 6.8 years) (group L). The ECGs of 35 patients (mean age, 26.4 ± 4.5) were obtained in both follicular and luteal phase. Both groups underwent a standard 12-lead surface electrocardiogram recorded at 50 mm/s. Maximal (Pmax) and minimal P wave durations (Pmin) were measured. P wave dispersion (PD) was defined as the difference between Pmax and Pmin. PD was significantly higher in group L than group F (46.6 ± 18.5 versus 40.1 ± 12.7; P < 0.05). Pmin was significantly lower in group L than group F (51.6 ± 12.1 versus 59.1 ± 12.1; P = 0.002). When we compared ECGs in different phases of the 35 patients, PD was significantly higher in luteal phase than follicular phase (53.2 ± 12.3 versus 42.8 ± 10.2; P < 0.05). Pmin was significantly lower in luteal phase than follicular phase (47.6 ± 6.6 versus 56 ± 10.1; P = 0.05). We detected a significant correlation between the day of the menses and PD (r = 0.27; P < 0.05). PD was increased in luteal phase compared to follicular phase, and this difference was more prominent as the days of the cycle progressed.