Assessment of endothelial function in patients with fibromyalgia--cardiac ultrasound study

In patients with fibromyalgia (FM) syndrome, stress and pain may chronically enhance sympathetic activity, altering cardiovascular response and inducing endothelial dysfunction. We investigated endothelial function in FM patients using echocardiography and analyzed whether endothelial function was affected by the clinical parameters of FM. Fifty-five postmenopausal women with FM and 35 healthy controls were included. Endothelial function was examined by brachial artery flow-mediated dilatation (FMD, endothelium dependent) and response to 40 μg of sublingual nitroglycerine (NTG-induced dilatation, endothelium independent). FM patients underwent manual tender point survey and completed visual analogue scale (VAS) of pain and fibromyalgia impact questionnaire (FIQ). The study participants were subdivided into two groups based on the sum of the FIQ score (group A, FIQ ≥ 50, group B, <50). The FMD value (5.7 ± 3.9% vs. 7.0 ± 1.4%, P = 0.008) and NTG-induced dilatation (12.5 ± 5.1% vs. 14.7 ± 2.5%, P = 0.006) were significantly lower in FM group than healthy control. There were no significant differences in FMD between groups A and B (5.4 ± 3.3% vs. 6.6 ± 3.5%, P = 0.19). However, significant decreases were noted in NTG-induced dilatation values of group A compared with those of group B (11.0 ± 4.4% vs. 14.3 ± 3.8%, P = 0.004). FMD and NTG-induced dilatation showed a significant inverse association with pain VAS and FIQ. Pain exerts a negative effect on endothelial function in FM patients, and that effect was significantly different according to the FIQ score.