Spontaneous baroreflex sensitivity: toward an ideal index of cardiovascular risk in hypertension?

Objective: Estimating the risk entailed by classical risk factors like blood pressure (BP) or serum cholesterol may be difficult because of their variability and the often unknown duration of exposure. Having variables integrating the impact of those classical risk factors on the cardiovascular system would probably aid the prediction of cardiovascular events. The present study aimed at determining whether cardiac baroreflex sensitivity (BRS), correlates with several risk factors and thus is a good candidate for being such an integrative variable. As a comparison, left ventricular mass (LVM), pulse wave velocity (PWV), and creatinine were also tested for association with risk factors.

Design: A total of 302 subjects referred for hypertension, were considered. They had a 24-h BP recording and a determination of BRS by two different methods (sequence and alpha coefficient), in two different positions (lying and standing). They were also tested for the presence of left ventricular hypertrophy (LVH) (by echocardiography and electrocardiogram) and had a PWV measurement. Biological testing included serum lipids, blood glucose, creatinine, proteinuria and urinary excretion of microalbumin.

Results: There was a strong correlation between the two methods of BRS measurement in each position (P < 0.001). BRS determined by the sequence method in the lying position was correlated significantly and independently with age, 24-h systolic BP, heart rate, and serum cholesterol with P values < 0.001, < 0.001, < 0.01, and < 0.05, respectively. In an univariate analysis, BRS was also correlated with echocardiographic LVM index (r = -0.21, P < 0.05) and PWV (r = -0.27, P < 0.001), which possibly reflects its dependence on both vascular and cardiac damages.

Conclusion: The present study supports the hypothesis that BRS could encompass the impact over time of several risk factors on the cardiovascular system. Thus, it may constitute a valuable parameter in assessing more precisely the risk of cardiovascular events.