One of the most common non-invasive techniques to study the baroreflex is the spectral analysis of blood pressure (BP) and heart rate variability. The recent use of carotid distension rate instead of BP has permitted to study the neural path of the baroreflex after fully controlling for the vascular component. We previously discovered a new compensatory mechanism, reporting that the neural baroreceptor sensitivity (BRS) is higher in subjects with high carotid stiffness. We aimed to test whether this new compensatory mechanism is maintained in subjects with metabolic syndrome (MS).

Methods: From the PPS3 study, a large epidemiological survey of working people of age 50–75, were selected 2835 individuals non-diabetic, non-smokers, untreated by either anti-hypertensive or lipid-lowering drugs, and free from overt or familiarity for cardiovascular disease. A total of 701, 1673 and 461 subjects with respectively 0, 1–2 and 3–5 criteria for MS were studied.

Results: Neural BRS decreases significantly from subjects with 0 (median 1.33, IQ1.15–1.49 normalized units) to those with 1–2 (median 1.30, IQ1.10–1.47) and 3–5 criteria for MS (median 1.26, IQ1.08–1.43). Neural BRS was not significantly increased in subjects with both high carotid stiffness and 3–5 criteria for MS (Figure 1), suggesting the presence of neuropathy in subjects with MS.

Conclusions: Neural BRS is reduced in subjects with MS. The compensatory, carotid stiffness-dependent, increase of neural BRS is abolished in subjects with MS.