Gender Difference in Subjective Symptoms Related to Paroxysmal Atrial Fibrillation Is Also Detected in Postmenopausal Women

Cardiac symptoms related to paroxysmal atrial fibrillation varied with menstrual cycle in a premenopausal woman

Atrial fibrillation, an arrhythmia observed more frequently in men than women, is induced by both sympathetic and parasympathetic autonomic nerve activations. The menstrual cycle in premenopausal women has been reported to modulate the autonomic nervous system: parasympathetic activity is dominant in the follicular phase and sympathetic activity is dominant in the luteal phase. However, the relationship between atrial fibrillation and the menstrual cycle has not yet been reported, because this arrhythmia is very rarely detected in premenopausal women. We experienced a 38 year-old woman with paroxysmal atrial fibrillation. Her menstrual cycle was 30.4 ± 0.5 days and the menstrual period was 3.9 ± 0.2 days for 22 cycles. Although she had taken flecainide 200 mg/day, bepridil 200 mg/day, and propranolol 20 mg/day, she sometimes experienced mild palpitations. QTc intervals measured at her visits to our clinic were 440 ± 3 msec in the follicular phase and 425 ± 2 msec in the luteal phase (P = 0.01). These changes in QTc intervals during the menstrual cycle are compatible with earlier reports. During the 22 menstrual cycles, she felt palpitations on 3.2 ± 0.7 days in the menstrual period, 6.4 ± 0.3 days in the follicular phase, and 4.1 ± 0.4 days in the luteal phase (P = 0.01). Afterward, the medication was changed from daily to periodic administration for one week beginning a couple of days before the expected menstrual time, and she did not feel symptomatic variation in her menstrual cycle. These data suggest that her symptoms related to atrial fibrillation might have been dependent on parasympathetic activity.

Effects of postmenopausal hormone therapy on incident atrial fibrillation: the Women's Health Initiative randomized controlled trials

BACKGROUND

Atrial fibrillation (AF) is less prevalent in women versus men, but associated with higher risks of stroke and death in women. The role hormone therapy plays in AF is not well understood.

METHODS AND RESULTS

The Women's Health Initiative randomized postmenopausal women to placebo or conjugated equine estrogens (0.625 mg/d) plus medroxyprogesterone acetate (2.5 mg/d) if they had a uterus (N=16 608) or to conjugated equine estrogens only if they had prior hysterectomy (N=10 739). Incident AF was identified by ECG and diagnosis codes from Medicare claims or hospitalization records. Hazard ratios for incident AF were estimated using Cox proportional hazards regression. After excluding participants with baseline AF, there were 611 incident AF cases over a mean of 5.6 years among 16 128 estrogen plus progestin participants, and 683 cases over a mean of 7.1 years among 10 251 conjugated equine estrogens alone participants. Incident AF was more frequent in the active groups of both trials, reaching statistical significance in the trial of conjugated equine estrogens alone in women with prior hysterectomy (hazard ratio, 1.17; CI, 1.00-1.36; P=0.045) and in the pooled analysis (hazard ratio, 1.12; CI, 1.00-1.24; P=0.05), but not in the estrogen plus progestin trial (hazard ratio, 1.07; CI, 0.91-1.25; P=0.44). These results were only minimally affected by adjustment for incident stroke, coronary heart disease, and heart failure.

CONCLUSIONS

Incident AF was modestly elevated in hysterectomized women randomized to postmenopausal E-alone, and in the pooled group randomized to E-alone or estrogen plus progestin. The trend in women with intact uterus receiving estrogen plus progestin, considered separately, was not statistically significant.

CLINICAL TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov; Identifier: NCT00000611.