Purpose: Several studies have shown that the augmentation index (AIx) is negatively correlated with heart rate (HR). This led some authors to claim that the use of HR-lowering drugs may be detrimental in hypertension. The aim of this study was to assess the longitudinal and cross-sectional relationships of HR with AIx and central blood pressure (BP) in 346 subjects from the HARVEST (mean age 30.7 ± 8.5 years).
Methods: At baseline, HR was measured with 24-h ambulatory recording. Central hemodynamics were evaluated with Specaway DAT system after a median of 8.0 years from baseline. In multivariate linear regression analyses, AIx and central systolic BP were used as dependent variables and night-time HR or office HR as predictors adjusting for several risk factors and confounders.
Results: In fully adjusted models, baseline night-time HR was a significant positive predictor of AIx (p < 0.001) and central BP (p = 0.014) measured 8 years later. Adjusted office HR measured at the time of arterial distensibility assessment was inversely correlated with AIx (p = 0.001) a relationship which was attenuated after physical activity (p = 0.004) and left ventricular ejection time (p = 0.015) were taken into account. In addition, office HR was inversely correlated with central BP (p = 0.039) a relationship which was no longer significant after physical activity and ejection time were accounted for.
Conclusions: These data show that HR measured during sleep is longitudinally associated with AIx and central BP. Thus, low HR in the long term may have beneficial effects on central hemodynamics and the wall properties of the large arteries in hypertension.
Keywords: Ambulatory; Aortic pressure; Arterial stiffness; Augmentation index; Heart rate; Hypertension.