Among Patients Taking Beta-Adrenergic Blockade Therapy, Use Measured (Not Predicted) Maximal Heart Rate to Calculate a Target Heart Rate for Cardiac Rehabilitation

Abstract

Purpose: Among patients in cardiac rehabilitation (CR) on beta-adrenergic blockade (βB) therapy, this study describes the frequency for which target heart rate (THR) values computed using a predicted maximal heart rate (HRmax), correspond to a THR computed using a measured HRmax in the guideline-based heart rate reserve (HRreserve) method. Methods: Before CR, patients completed a cardiopulmonary exercise test to measure HRmax, with the data used to determine THR via the HRreserve method. Additionally, predicted HRmax was computed for all patients using the 220 − age equation and two disease-specific equations, with the predicted values used to calculate THR via the straight percent and HRreserve methods. The THR was also computed using resting heart rate (HR) +20 and +30 bpm. Results: Mean predicted HRmax using the 220 − age equation (161 ± 11 bpm) and the disease-specific equations (123 ± 9 bpm) differed (P < .001) from measured HRmax (133 ± 21 bpm). Also, THR computed using predicted HRmax resulted in values that were infrequently within the guideline-based HRreserve range calculated using measured HRmax. Specifically, 0 to ≤61% of patients would have had an exercise training HR that fell within the guideline-based range of 50-80% of measured HRreserve. Use of standing resting HR +20 or +30 bpm would have resulted in 100% and 48%, respectively, of patients exercising below 50% of HRreserve. Conclusions: A THR computed using either predicted HRmax or resting HR +20 or +30 bpm seldom results in a prescribed exercise intensity that is consistent with guideline recommendations for patients in CR.

Missing the Target

“…Furthermore, recent evidence suggests that HR-guided exercise training may be superior to RPE-based exercise for improving CRF in CR. 13 In summary, this important work by Keteyian and colleagues 8 highlights the need to reevaluate methods for prescribing exercise intensity in CR. As exercise intensity is the most critical aspect of exercise prescription for stimulating improvements in CRF, it is imperative that an adequate intensity be implemented.…”

“…In this issue of the Journal of Cardiopulmonary Rehabilitation and Prevention, Keteyian and colleagues 8 conducted an elegant study to describe the frequency for which target HR is accurately achieved when exercise intensity is not based on actual HR max in patients taking β-blocker medications in CR. A cohort of 166 patients from the iATTEND (improving ATTENDance to CR) trial, which was racially diverse (55% Black) and included both men and women, was examined.…”