Macrovascular Function Assessed By Flow-mediated Dilation Does Not Change Across Menstrual Cycle Regardless Of Race

Abstract

A race disparity in vascular function has been identified between premenopausal black women and white women during the low hormone phase of the menstrual cycle. However, to the best of our knowledge, no previous study assessing macrovascular function across the menstrual cycle has reported the racial characteristics of their participants. PURPOSE: To assess macrovascular function across the menstrual cycle in a racially diverse group of young, normotensive, non-obese, naturally cycling women using brachial artery flow-mediated dilation (FMD). METHODS: Participants self-identified as either non-Hispanic white (WHW), non-Hispanic black (BLW), or Hispanic (HW). FMD was performed during three menstrual phases: early follicular (EF; first 1-5 days of menstruation), ovulation (OV; determined by an at-home ovulation test, 1-3 days surrounding the luteinizing hormone surge), and mid-luteal (ML; 7-to-10 days post ovulation, depending on cycle length). Brachial artery diameter and blood velocity were assessed using Doppler ultrasound. A one-way between subjects ANOVA was used to compare participant characteristics between racial groups. A two-way mixed model ANOVA was used to compare FMD between racial groups across menstrual phases. Data are presented as mean ± standard deviation. RESULTS: The present study included 20 WHW (25±6 years), 12 BLW (24±5 years), and 8 HW (24±4 years). Groups had similar cycle lengths (WHW 29±2; BLW 30±4; HW 31±5 days; p=0.61) and testing was conducted on similar days during each phase (data not shown, all p>0.05). Baseline brachial artery diameters were not different between races (p=0.68) or across phases (p=0.37). The vasodilatory response to FMD (FMD%) was not influenced by race (p=0.57) or phase (p=0.71) nor was there a significant interaction between race and phase (p=0.23) (WHW: EF 8.1±1.7, OV 7.5±2.8, ML 8.1±2.0%; BLW: EF 6.8±2.5, OV 6.9±2.3, ML 8.6±3.0%; HW: EF 8.2±2.4, OV 8.9±4.1, ML 7.6±2.3%). CONCLUSION: These preliminary findings indicate that macrovascular function assessed by FMD% does not change across the menstrual cycle, regardless of race. These data also suggest FMD% is a stable measure of macrovascular function in premenopausal women.