Maximum heart rate prediction in children: are maximal heart rate prediction equations suitable for use in paediatric clinical practice?

Abstract

Aims: Assessment of maximal heart rate is used in clinical practice to determine the degree of beta-blockade during exercise and periods of adrenergic stress. When direct measurement is not possible, indirect methods utilising heart rate prediction equations are commonly used, but their validity in children has been challenged.

Methods: Retrospective data on 109 healthy children (male 63, 58%; mean age 11.00 ± 3.09) undergoing routine exercise testing were analysed. Measured maximal heart rate was compared with estimates obtained from twenty-two prediction equations.

Results: All prediction equations overestimated maximal heart rate in males. In females, two equations underpredicted (Fairbarn and Heinzmann-Filho et al.), whilst the remaining equations overpredicted. The equations that predicted most accurately differed between males (Fairbarn) and females (Whyte (males). The prediction equation used commonly in clinical practice, Fox (220-age), overestimated significantly in males and females (p = < 0.001). A moderate positive correlation with age and maximal heart rate was seen in males only (r = 0.3195, p = 0.0107).

Conclusions: This study shows that adult age regression equations do not accurately predict childhood maximal heart rate as determined by exercise testing. An inability to accurately predict maximal heart rate could have important implications for both childhood exercise prescription and the safe monitoring of pharmacological therapy that limits exertional heart rate response in children with inherited arrhythmic syndromes. In the absence of direct measurement of maximal heart rate, alternative paediatric-specific prediction methods should be developed to ensure appropriate estimation of childhood maximal heart rate.