Associations of Daytime, Nighttime, and 24‐Hour Heart Rate With Four Distinct Markers of Inflammation in Hypertensive Patients: The Styrian Hypertension Study

The current study assessed which measure of heart rate (HR) is most associated with inflammatory activity. Among 368 hypertensive patients (mean age±standard deviation, 60.6±10.8; 52.9% women), mean daytime (from 6 am to 10 pm), nighttime (from 10 pm to 6 am), and 24-hour HR were recorded using a continuous 24-hour ambulatory blood pressure monitoring portable device. Associations of daytime, nighttime, and 24-hour HR with leukocytes, platelets, C-reactive protein (CRP), and 25-hydroxyvitamin D were calculated using multivariate linear regression, reporting unstandardized coefficients (B) with standard errors (SEs). Mean daytime, nighttime, and 24-hour HR were 73, 64, and 71 beats per minute, respectively. All HR measures were positively associated with leukocytes after adjustment. Nighttime HR was additionally related with higher CRP. When all HR measures were simultaneously added to a single multivariate model, only the positive associations of nighttime HR with leukocytes (B [SE]=0.06 [0.03], P=.04), as well as with CRP (B [SE]=0.20 [0.07], P=.005), persisted. Nighttime HR was more closely associated with inflammatory activity. These observations lend some insight toward the pathophysiological mechanisms that implicate HR in cardiovascular risk and provide valuable direction for forthcoming investigations.