Evidence for a Role of Hot Flushes in Vascular Function in Recently Postmenopausal Women

Observational studies indicate that postmenopausal hormone therapy (HT) prevents cardiovascular disease, but randomized clinical trials have not confirmed this effect. Hot flushes were more likely to be present in women starting HT in observational studies, whereas these symptoms were mild or absent among women attending randomized clinical trials. We hypothesized that vascular function may differ in women with and without vasomotor hot flushes. One hundred forty-three recently postmenopausal women showing a broad range of variation in hot flushes were studied with radial artery tonometry. Pulse wave analyses were assessed at baseline and after nitroglycerin and salbutamol challenges. Wilcoxon signed rank test was used for paired comparisons after challenges with nitroglycerin and salbutamol. Neither baseline arterial stiffness nor endothelial function differed between women without or with mild, moderate, or severe hot flushes. However, after nitroglycerin challenge, the time to the onset of the reflected wave (dependent on pulse wave velocity) was 9.5% longer (P=.014), and the time to the first systolic peak (dependent on the rapid phase of ventricular ejection) was 13.9% longer (P=.025) in women with severe hot flushes as compared with asymptomatic women. Women with severe vasomotor hot flushes show greater vascular responsiveness to nitroglycerin than women without hot flushes. This may partially explain the conflicting data between observational and randomized HT studies. ClinicalTrials.gov, www.clinicaltrials.gov, NCT00668603 II.