Reliability of Resting Heart Rate-based Target Heart Rate for Exercise Prescription after Acute Myocardial Infarction

Anaerobic threshold (AT) assessment using cardiopulmonary exercise testing (CPX) during hospitalization is considered ideal for prescribing exercise regimens in patients with acute myocardial infarction (AMI). However, practical limitations often hinder its implementation. This study evaluated strategies for prescribing exercise based on resting heart rate (RHR).

A total of 194 consecutive male patients with AMI who underwent CPX within 13 days of hospitalization were enrolled. Bland-Altman analysis was performed to assess the agreement between the heart rate (HR) at AT (ATHR) and RHR +20, +25, and +30 beats. Multiple regression analysis was conducted to identify factors influencing ΔHR (ATHR-RHR). Decision-tree analysis was used to establish thresholds for appropriate exercise prescriptions based on RHR.

Regardless of β-blocker use, the RHR + 25 formula most closely approximated the ATHR in patients who underwent early CPX after AMI. Multivariate analysis identified RHR and hemoglobin (Hb) as significant predictors of ΔHR. Decision-tree analysis indicated that RHR + 25 was appropriate when RHR <91 bpm and Hb ≥12.0 g/dL.

RHR + 25 is a practical alternative for determining the target HR in post-AMI rehabilitation among male patients, particularly in those with RHR <91 bpm and Hb ≥12.0 g/dL, when CPX is not feasible.