Heart rate as a predictor of future blood pressure in schoolchildren

Abstract

Heart rate (HR) has been shown to predict future blood pressures (BP) in studies in adults. We explored the relation of HR to future BP levels in a cohort of 344 black and 456 white schoolchildren ages 5 to 19 years, to examine the hypothesis that HR predicts subsequent BP even very early in life. After making baseline measurements, BP was assessed longitudinally 1 to 24 additional times (mean = 8.25) after the baseline period, at intervals of approximately 6 months. We found that HR was significantly related to future diastolic BP in the black boys ( P = .016) after adjusting for baseline diastolic BP, age, and body mass index, but not in the black girls or in the white children. Because HR is reflective of sympathetic nervous system (SNS) activity that in turn can be related to the renin-angiotensin system (RAS), we also explored the relation of HR to the RAS by studying relationships to variants in the angiotensinogen gene and the angiotensin I-converting enzyme (ACE) gene. We found a significantly positive relationship of HR to the presence of the deletion allele of the ACE gene ( P = .0015), but, again, only in the black boys. Because blacks in general appear to retain additional sodium when compared with whites, the SNS, as reflected in the HR, may influence BP more when individuals have increased sodium retention. In summary, baseline HR predicted future diastolic BP in the black boys but not in the black girls or in the white children.