The Influence of Resting Heart Rate on Central Pulse Pressure is Age-Dependent.

Abstract

Low resting heart rate (RHR) increases augmentation pressure (AP) and central pulse pressure (central PP) and decreases peripheral pressure wave amplification. Given that the contribution of AP to central PP increases with age we hypothesized that the influence of RHR on AP, central PP and peripheral amplification varies with age. To evaluate the interaction between age and RHR on the forward and backward components of central PP. A cohort of 1249 ambulatory hypertensive patients with good quality radial wave recordings was stratified into age groups and quartiles of RHR (<61, 61-68, 69-76 and > 76 bpm). Central aortic pressure was estimated from radial applanation tonometry. Forward wave (FW) and AP showed opposite changes until midlife, mutually canceling their effect on central PP, whereas both components of central PP increased in parallel after the fifth decade. The initial fall in FW was expressed in the brachial artery as a corresponding decrease in PP and in peripheral amplification. After midlife there was a further decrease in peripheral amplification at the expense of the rise in central PP. A lower RHR exaggerated the age-related increase in left ventricular ejection time (LVET), AP, central PP, and the decrease in peripheral amplification (P < 0.001, for all the interactions between decades and quartiles of RHR). Multivariable regression analyses (n = 1249) confirmed a significant interaction between age and RHR on central PP (P < 0.001), AP (P < 0.001), LVET (P < 0.001), AIx (P < 0.035), and peripheral amplification (P < 0.001). Multivariable regression analyses stratified by age groups (< 30, 30-59 and ≥ 60 years) showed an increasing strength in the relationship of RHR with AP, independently of sex, mean arterial pressure, pulse wave velocity and beta-blockers use. The average increase in AP for a decrease in 10 bpm was 1.4 mmHg before age < 30 years; 2.5 mmHg between age 30-59 years; and 5.4 mmHg at 60 years and older. A lower heart rate exaggerated AP and central PP in an age dependent fashion, being the effect particularly relevant in older patients.