How does the estimated phase of menstrual cycle or menopause influence the prevalence of vasovagal syncope induced by head-up tilt test.

BACKGROUND The purpose of this study was to evaluate the prevalence of syncope induced by head-up tilt test (HUTT) and the type of positive vasovagal response to the orthostatic stress in a relationship to the estimated phase of menstrual cycle (follicular phase, luteal phase) or menopause. METHODS We observed a cohort of 500 women at age 13-89 years (median of age 37.5), referred to HUTT. Phase of the menstrual cycle was determined on the basis of the usual length of menstrual cycle and the day of the cycle at the time of the study. We assumed that the length of the luteal phase is constant and it is 14 days. RESULTS In premenopausal patients, the occurrence of the mixed and cardioinhibitory response was significantly more frequent in comparison to postmenopausal women (48.8 vs. 35.1% and 19.7 vs. 12.4%, respectively; p < 0.00001), while the occurrence of the vasodepressive one was significantly less frequent (7.3% vs. 28.6%; p < 0.00001) in that group of patients. Women in follicular phase presented vasodepressive response during HUTT more often than woman in the luteal phase (10.0% vs. 4.1%, p < 0.00001). CONCLUSIONS Among women referred for HUTT, the prevalence of the vasovagal syndrome did not differ between those that were pre- and post-menopausal. Higher incidence of vasodepressive reaction in postmenopausal women was observed. Among the premenopausal women, the vasodepressive type of vasovagal syndrome occurred more often in follicular then in luteal phase.