Comparison of the physiologic and prognostic implications of the heart rate versus the RR interval

Abstract

Background The HR and RR interval are inversely related. Objective To determine which parameter better describes the autonomic changes that occur after exercise and which provides stronger prognostic significance. Methods Healthy volunteers (n=33) underwent sequential bicycle exercise tests with selective autonomic blockade during exercise to define the HR and RR interval changes in recovery due to parasympathetic effect, sympathetic effect, and sympathetic-parasympathetic interaction. The prognostic significance of resting HR and RR interval was assessed in a cohort study (n=33,781). The prognostic significance of exercise HR and RR interval and 1-minute HR and RR interval recovery was assessed in patients referred for exercise testing (n=2387). Results Parasympathetic effect on HR and RR interval both increased in recovery (p<0.001), while the sympathetic effect on HR declined (p<0.001) and the sympathetic effect on the RR interval paradoxically increased. Significant sympathetic-parasympathetic interaction was noted with the HR analysis but not with the RR interval. Resting HR and RR interval had similar prognostic implications by age and gender. While resting and exercise HR and RR interval had similar prognostic implications, 1-minute HR recovery was a multivariate predictor of mortality (HR 0.81; 95%CI 0.69–0.95), while 1-minute RR interval recovery was not. Conclusions Based on these findings, the HR (and its changes) are not necessarily interchangeable with the RR interval (and its changes) in either physiologic or prognostic studies. It is important to consider underlying physiologic constraints and identify wisely which parameter (or even other transformation of these parameters) is most suitable for a given analysis.

Carotid chemoreflex activity restrains post‐exercise cardiac autonomic control in healthy humans and in patients with pulmonary arterial hypertension

“…; Goldberger et al . ); (3) short‐term time constant of HRR (T30) calculated as the negative reciprocal of the slope obtained from a linear regression between the first 30 s HR data natural log‐transformed (Imai et al . ); and (4) long‐term time constant of HRR (HRRt) obtained via non‐linear regression between RR intervals and time using data from peak exercise to 300 s of recovery (Imai et al .…”

“…; Goldberger et al . ). Thereafter, vagal activity continues to increase at a smaller rate, while sympathetic activity progressively decreases (Imai et al .…”

“…; Goldberger et al . , ). Together, these changes in vagal and sympathetic activity lead to further decreases in HR and an increase in HR variability (HRV) (Pomeranz et al .…”

“…; Goldberger et al . , ). As a result, post‐exercise HRR and HRV provide information about the recovery of cardiac autonomic control following exercise.…”

Repeatability and Reliability of Heart Rate Variability in Healthy, Adult Pony Mares

“…MeanHR for the CF comparisons may be due to the reciprocal nature of these variables, that does not allow them to be directly substituted for each other [50]. Results also showed that the use of No, Low Garza et al [37] compared Strong and Very Strong CF and excluded data obtained via the Very Strong CF due to "significant difference in output" between them, although the methodology followed or results were not described.…”