Influence of aging and other cardiovascular risk factors on baroreflex sensitivity

OBJECTIVES: To examine the influence of known cardiovascular risk factors ( cholesterol, blood glucose levels, arterial pressures, heart rate, and agin g) on baroreflex sensitivity. DESIGN: An observational epidemiological study. SETTING: Geriatric Division at the Policlinico Umberto Primo, University of Rome La Sapienza. PARTICIPANTS: Two hundred three subjects whose ages ranged from 9 to 94 yea rs, apparently healthy and free of detectable clinical evidence of atherosc lerosis. MEASUREMENTS: All subjects underwent determination of baroreflex sensitivit y by phenylephrine infusion (BS,,,), and by a noninvasive method derived fr om spectral analysis of R-R interval and arterial pressure variabilities (a index). RESULTS: The population, subdivided into tertiles for each variable studied , had lower BSphe values and lower a indexes as a function of age, plasma l ow-density lipoprotein (LDL) cholesterol, and systolic blood pressure. The a index was significantly lower in both groups with elevated LDL cholestero l levels than in those with lower levels (II and III vs I tertile, P < .001 ), whereas BSphe, differed significantly only in the two groups who had ext reme levels of LDL (I vs III fertile, P < .001). Multiple regression analys is identified a negative association of the alpha index with age (P < .001) , heart rare (P < .01), area under the glucose-response curve (P < .001), a nd LDL cholesterol (P < .01), but of BSphe only with age (P < .001) and hea rt rate (P < .01). CONCLUSION: These findings indicate that some risk factors for coronary hea rt disease adversely influence baroreflex sensitivity.