Heart rate recovery is impaired after maximal exercise testing in children with sickle cell anemia

Abstract

Objective: To examine heart rate recovery (HRR) as an indicator of autonomic nervous system dysfunction after maximal exercise testing in children and young adults with sickle cell anemia (SCA).

Study design: Recovery phase heart rate (HR) in the first 5 minutes after maximal exercise testing in 60 subjects with SCA and 30 matched controls without SCA was assessed. The difference between peak HR and HR at both 1-minute (ΔHR1min) and 2-minutes recovery was our primary outcome.

Results: Compared with controls, subjects with SCA demonstrated significantly smaller mean ΔHR1min (23 beats per minute [bpm], 95% CI 20-26 vs 32 bpm, 95% CI 26-37, P = .006) and the difference between maximal HR and HR at 2 minutes (39 bpm, 95% CI 36-43 vs 48 bpm, 95% CI 42-53, P = .011). Subjects with SCA also showed smaller mean changes in HR from peak HR to 1 minute, from 1 minute to 2 minutes, and from 2 through 5 minutes of recovery by repeated-measures testing. In a multivariable regression model, older age was independently associated with smaller ΔHR1min in subjects with SCA. Cardiopulmonary fitness and hydroxyurea use, however, were not independent predictors of ΔHR1min.

Conclusions: Children with SCA demonstrate impaired HRR after maximal exercise. Reduced postexercise HRR in SCA suggests impaired parasympathetic function, which may become progressively worse with age, in this population.

Copyright © 2015 Elsevier Inc. All rights reserved.

Figures

Figure

Calculated time constants demonstrate prolonged HRR over the first 5 minutes of recovery following exercise challenge in subjects (solid line) with SCA compared with controls (dotted line) (T = 128 sec, 95% CI [123, 134] vs. 109 sec, 95% CI [103, 116]). HRR curves are shown with individual (top) and aggregate (bottom) heart rate data.

Figure

Calculated time constants demonstrate prolonged HRR over the first 5 minutes of recovery following exercise challenge in subjects (solid line) with SCA compared with controls (dotted line) (T = 128 sec, 95% CI [123, 134] vs. 109 sec, 95% CI [103, 116]). HRR curves are shown with individual (top) and aggregate (bottom) heart rate data.