Old and new equations for maximal and anaerobic threshold heart rate prediction in coronary heart disease in Chinese population.

Background: The prediction of maximal heart rate (MHR) and anaerobic threshold heart rate (HRAT) in patients with coronary heart disease (CHD), particularly among the Chinese population, remains a significant challenge. Existing equations for MHR prediction are primarily designed for healthy individuals not on medication for optimized β-blocker (BB) therapy, showing limited efficacy for individuals on various drug regimens. Moreover, the prediction of HRAT lacks established formulas. This study aims to develop equations for MHR and HRAT, assess the accuracy of historical MHR formulas, and examine their correlation with HR measurements at the anaerobic threshold (AT).

Methods: Among 2021 to 2023, 170 CHD patients were recruited. Patients were categorized into groups based on BB usage. BB dose was transformed into carvedilol dose. Multiple linear stepwise regression analysis was employed to identify predictors of MHR and HRAT, incorporating key patient variables according to prior studies (age, sex, height, weight, carvedilol dose, HRrest). The mean absolute percentage errors (MAPEs) were calculated and compared among abovementioned MHR and HRAT prediction formulas. Besides, the percentages of MHR in predicting HRAT among different formulas were calculated.

Results: For the patients with BB medication, the simplified equations derived for MHR and HRAT were 176 - 1.2*age + 0.7*HRrest - 0.4*weight and 98 - 0.6*age + 0.7*HRrest - 0.3*weight, respectively. For those without BB medication, the derived equations for MHR and HRAT were 200 - 1.1*age and 91 - 0.5*age + 0.5*HRrest, respectively. There are significant differences between the results predicted by the new formula and the prior formulas. The new formulas are helpful for predicting the MHR of patients during exercise more accurately and guiding exercise training more scientifically.

Conclusions: The new equations for estimating MHR and HRAT in CHD patients enhance the accuracy of prior formulas. Given the BB impact on sympathetic nerve activity, the predictive formulas for MHR and HRAT were significantly improved.