Influence of coronary artery disease risk factors on baroreflex sensitivity in the elderly

Abstract.

In this study, we assessed whether baroreflex sensitivity (BRS) is influenced by risk factors of cardiovascular disease. Subjects of this study were 95 elderly people (40 males and 55 females; mean age ± SD, 66.6±1.6 years) who underwent a medical check-up. BRS was determined as the gain of transfer function in baroreflex arc by spectral analysis of mean blood pressure and R-R interval variabilities in low-frequency band (0.04–0.15 Hz). Gender-related differences in BRS and relationships between BRS and various risk factors of cardiovascular disease were investigated. The value of BRS was significantly higher in males [10.7±3.7 (SD) ms/mmHg] than in females [9.0±4.0 ms/mmHg, p< 0.05]. However, this gender-related difference disappeared when other variables were taken into account in the multivariate model. Multiple regression analyses showed independent inverse relationships between BRS and heart rate [b=–0.016±0.004 (SE) bpm, β=–0.39], and between BRS and platelet count [b=–0.002±0.001 × 103/µl, β=–0.22]. Our results indicated that BRS is inversely related to platelet count in the elderly population. The precise mechanism of this correlation is unknown, but platelet factors released from platelet aggregates can potentially influence vascular function and modify BRS, or there is a common underlying determinant responsible for the covariation.