The second trial, the MSHeart Study, enrolled 189 women aged 40-60. All were nonsmokers with no history of CVD. All of the women had intact uteri and ovaries, and enrollees could not be using hormones or other medications that could affect vascular function (beta-blockers, calcium channel blockers, insulin, or selective serotonin reuptake inhibitors/selective norepinephrine reuptake inhibitors). Participants again underwent extensive evaluation.
Women in the MSHeart Study received a full 24 hours of objective physiologic hot flash monitoring via an external monitoring system as well as FMD evaluation by brachial artery ultrasound. Women were stratified by age into three groups: younger than 53, 53-56, and greater than age 56.
For the youngest group of women in the second study, increased frequency of objectively verified hot flashes was associated with lower FMD and poorer endothelial dysfunction (P < 0.05). The association was not significant for either of the older two groups when taken separately; however, when pooled data for participants of all ages were considered, the interaction between age and hot flash frequency was associated with reduced FMD (P = 0.02). These associations held true after adjusting for the covariates of age, race, BMI, blood vessel diameter, menopausal stage, and any prior hormone use.
These two studies, said Dr. Thurston, “may point to subgroups of women that need targeted cardiovascular prevention” by identifying early VMS as a mechanistic pathway for endothelial dysfunction. Dr. Richard Chazal, ACC vice president and session moderator, noted that the MSHeart Study in particular succeeded in “leveraging physiologic symptoms and markers, as well as the flow mediated functional dilation that we all would expect.”
The studies were sponsored by the National Heart, Lung, and Blood Institute of the National Institutes of Health.